Page 2 of 6 FirstFirst 123456 LastLast
Results 51 to 100 of 279
  1. #51
    mtbr member
    Reputation: Velobike's Avatar
    Join Date
    Jun 2007
    Posts
    6,332
    Quote Originally Posted by smilinsteve View Post
    Riding off trail by its very nature causes damage; more or less depending on where you do it.
    There is pristine wilderness where even on- trail riding is not allowed. There is no way you can "gently" ride though wilderness. You change it. There is good reason to disallow this kind of riding in many places.
    That's one of the advantages of a fatbike.

    My 4" tyres make much less impression on the soil than a rambler or a deer.

    I suspect the ultimate offroad bike (as opposed to mtb built trails and hardpacked dirt) would be a Cleland style with the new Surly Krampus 29er+ tyres or the 4" fat tyres.

    This type of bike is not about speed, it's about getting there and enjoying the view while doing so, otherwise you may as well go to a velodrome or some other bicycle playground/trailpark and go really fast.

    The comparisons to the 1890s and early 1900s 28" rimmed bikes aren't really valid. Those were designed for road work, albeit on dirt roads, and they are just about unrideable if you try to take them through the sort of stuff that the Cleland bikes get ridden through. Around 1900 28" rimmed bikes were being sold with 2" tyres in Australia for bush work. This would have been of some help in the bulldust areas, but the geometry was unsuited for any technical offtrail use.

    My opinion is based on having owned several early 1900s 28" wheeled bikes and a recent attempt to build a retro 29er mtb out of one. It will require considerable changes to the bike's geometry - which I'll do because it's fun. If it works I'll post it up in this forum - it will get raced - but it will probably end up more like an early Scottish path racer than 29er.
    Last edited by Velobike; 09-21-2012 at 05:17 PM.
    As little bike as possible, as silent as possible.
    Latitude: 57º36' Highlands, Scotland

  2. #52
    mtbr member
    Reputation: smilinsteve's Avatar
    Join Date
    Jul 2009
    Posts
    8,613
    Quote Originally Posted by Velobike View Post
    That's one of the advantages of a fatbike.

    My 4" tyres make much less impression on the soil than a rambler or a deer.
    You may be right, but regardless of your tire size, in most of the places I ride or have ridden, riding off trail is wrong.

  3. #53
    transmitter~receiver
    Reputation: meltingfeather's Avatar
    Join Date
    May 2007
    Posts
    8,953
    Quote Originally Posted by Velobike View Post
    That's one of the advantages of a fatbike.

    My 4" tyres make much less impression on the soil than a rambler or a deer.

    I suspect the ultimate offroad bike (as opposed to mtb built trails and hardpacked dirt) would be a Cleland style with the new Surly Krampus 29er+ tyres or the 4" fat tyres.

    This type of bike is not about speed, it's about getting there and enjoying the view while doing so, otherwise you may as well go to a velodrome or some other bicycle playground/trailpark and go really fast.
    Yet they still make an impression. "Ultimate" means irreparable destruction? It does in the cryptobiotic soils of the American southwest, where trails provide sustainable recreation.
    Your rose colored glasses and romaticized picture of "enjoying the view" don't change the facts. Some people prefer to go as fast as they can. They call it fun, and suggesting it belongs in a velodrome is ridiculous to the point of absurdity.
    Just because it isn't your flavor doesn't make speed any lesser of an enjoyable ride quality Grant, er... I mean, Velobike.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
    29er Tire Weight Database

  4. #54
    mtbr member
    Reputation: Velobike's Avatar
    Join Date
    Jun 2007
    Posts
    6,332
    Quote Originally Posted by meltingfeather View Post
    Yet they still make an impression. "Ultimate" means irreparable destruction? It does in the cryptobiotic soils of the American southwest, where trails provide sustainable recreation....
    If a deer can posthole it, I will ride on it. Humans are part of the landscape too.


    Quote Originally Posted by meltingfeather View Post
    ...Your rose colored glasses and romaticized picture of "enjoying the view" don't change the facts. Some people prefer to go as fast as they can. They call it fun, and suggesting it belongs in a velodrome is ridiculous to the point of absurdity.
    Just because it isn't your flavor doesn't make speed any lesser of an enjoyable ride quality Grant, er... I mean, Velobike.
    Yep, just as absurd as not appreciating that some people are not interested in speed. And who's Grant?
    As little bike as possible, as silent as possible.
    Latitude: 57º36' Highlands, Scotland

  5. #55
    transmitter~receiver
    Reputation: meltingfeather's Avatar
    Join Date
    May 2007
    Posts
    8,953
    Quote Originally Posted by Velobike View Post
    If a deer can posthole it, I will ride on it. Humans are part of the landscape too.
    I'm glad you don't live around here. That's the attitude that destroys wilderness recreation areas.
    Quote Originally Posted by Velobike View Post
    Yep, just as absurd as not appreciating that some people are not interested in speed. And who's Grant?
    Ah, yes... this is true of course. The thing is though, nobody who enjoys speed is here saying "enjoy the view" riders should be on handicap-access paths at old folks homes. It's a pretty typical retro-grouch, my-way-is-better attitude. Grant is Grant Petersen, the retro-grouch and Lycra/go-fast denigrating archetype. You would probably love his writings. Look up the blog on the Rivendell Bicycles website.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
    29er Tire Weight Database

  6. #56
    mtbr member
    Reputation:
    Join Date
    Feb 2011
    Posts
    882
    [QUOTE=meltingfeather;9712835]I'm glad you don't live around here. That's the attitude that destroys wilderness recreation areas. (self contradictive?)

    Come now...if man was not part of nature, nature left to itself...dies. Nothing would stay the same. Nature is a process of life unto death followed by rebirth. Nature is a part of creation, it is not GOD, to be held above man.

    Fat bike type tires provide the best means to traverse over the earth while doing the least change to the soil. This fact has been deomstrated in many photos posted by Velobike himself.

    Here in the states the 'goverment' owned lands belong to...we the people. More and more...we the people are being shut out from enjoying OUR land. A small minority uses as an excuse the abuses of a few to close them down. Truth is it is all about control...control of...we the people by those who who would restrict freedom at any level.

    But back on track...the Cleland bicycle shod with fat bike tires presents a type that should cause one to rejoice at the prospect of traversing the land with the least change.
    Is this not progress?

  7. #57
    mtbr member
    Reputation:
    Join Date
    Oct 2008
    Posts
    221
    Quote Originally Posted by meltingfeather View Post
    Yet they still make an impression.....Some people prefer to go as fast as they can. They call it fun, and suggesting it belongs in a velodrome is ridiculous to the point of absurdity.
    Just because it isn't your flavor doesn't make speed any lesser of an enjoyable ride quality....
    Well personally, I love to ride slowly and I also love to ride as fast as I can.

    Riding fast in itself, is not inherently more destructive to the environment. Especially when using low pressure tires, there is a strong argument that the faster you go the less time the ground has to compress and so the shallower the impression left behind. Also a higher gear means that the acceleration from each pedal stroke is spread over a larger distance and more momentum is maintained in-between pedal strokes

    The problem is more to do with braking and cornering habits. Clelands use low pressure tires on narrow rims which means you can't do violent tail slides without the tires rolling off the rims. The fact that 80% of the weight is over the rear wheel means that front tires float over the terrain causing little damage We also use the best modulated brakes we can find in order to avoid unintended lock-outs, and elliptical gears as a form of traction control. However, though authorities may ban bikes because of the damage caused by inappropriately aggressive riding, the careful and considerate also have to live with the consequences.

    Low pressure tires, bike design and considerate riding can keep environmental damage to the minimum. And whilst most ecosystems will quickly heal from the damage caused by an occasional rider, large rider numbers on a single trail will inevitably lead to long term damage.


    Since this is a 29er thread.
    Here's a picture of a Geoff and a 1981 700c x 47mm Cleland Range-Rider. Taken in 1984, this picture appeared in Charlie Kelly's 1988 "mountain Bike Book"
    Attached Thumbnails Attached Thumbnails Cleland: The original big wheeled off-road bicycle?-4321632293_01fcfb3fa1_b.jpg  


  8. #58
    mtbr member
    Reputation:
    Join Date
    Sep 2012
    Posts
    50
    At the moment, I'm running 65mm tyres, and before long will have some 75mm tyres. Still have some clearance, chainline and fender problems to resolve yet. There's no way I can squeeze anything wider into the current Aventura frame, and there's no way I can afford a new frame for the foreseeable future.

    That old 29er still exists. We're hoping someone can restore it so it can be displayed in a museum. This is how it looks today.
    Attached Thumbnails Attached Thumbnails Cleland: The original big wheeled off-road bicycle?-dscf2760.jpg  


  9. #59
    transmitter~receiver
    Reputation: meltingfeather's Avatar
    Join Date
    May 2007
    Posts
    8,953
    Quote Originally Posted by GrahamWallace View Post
    Well personally, I love to ride slowly and I also love to ride as fast as I can.

    Riding fast in itself, is not inherently more destructive to the environment. Especially when using low pressure tires, there is a strong argument that the faster you go the less time the ground has to compress and so the shallower the impression left behind. Also a higher gear means that the acceleration from each pedal stroke is spread over a larger distance and more momentum is maintained in-between pedal strokes

    The problem is more to do with braking and cornering habits. Clelands use low pressure tires on narrow rims which means you can't do violent tail slides without the tires rolling off the rims. The fact that 80% of the weight is over the rear wheel means that front tires float over the terrain causing little damage We also use the best modulated brakes we can find in order to avoid unintended lock-outs, and elliptical gears as a form of traction control. However, though authorities may ban bikes because of the damage caused by inappropriately aggressive riding, the careful and considerate also have to live with the consequences.

    Low pressure tires, bike design and considerate riding can keep environmental damage to the minimum. And whilst most ecosystems will quickly heal from the damage caused by an occasional rider, large rider numbers on a single trail will inevitably lead to long term damage.


    Since this is a 29er thread.
    Here's a picture of a Geoff and a 1981 700c x 47mm Cleland Range-Rider. Taken in 1984, this picture appeared in Charlie Kelly's 1988 "mountain Bike Book"
    Well put, and I don't disagree.
    However, I don't think a Cleland or fat bike should be a license to do whatever you want. Sustainability is key, which sometimes means using trails.
    Rants about access are misplaced, or at least way off topic.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
    29er Tire Weight Database

  10. #60
    mtbr member
    Reputation: Velobike's Avatar
    Join Date
    Jun 2007
    Posts
    6,332
    Quote Originally Posted by Sand Rat View Post
    ...Come now...if man was not part of nature, nature left to itself...dies. Nothing would stay the same. Nature is a process of life unto death followed by rebirth. Nature is a part of creation, it is not GOD, to be held above man.....
    ...the Cleland bicycle shod with fat bike tires presents a type that should cause one to rejoice at the prospect of traversing the land with the least change.
    Is this not progress?
    Well said.

    As a descendant of people who were forcibly cleared of their land to create what is now promoted as "wilderness" I am deeply suspicious of the exclusionary dictums of the urban eco-aesthetes of wealthy western countries.

    And back on track, or should I say "off track", I can't think of a better way to traverse soft country than with a fatbike. The geometry of a Cleland bike looks to me ideal for the sort of slow going that that entails. Whether it is marketable to a population to whom mountainbiking involves leaping, sliding, and thrashing round a maintained trail as fast as possible, is another story though. It's a completely different category of bike. To use a motorbike analogy, a Rokon compared to a motocross bike.
    Last edited by Velobike; 09-22-2012 at 05:04 PM.
    As little bike as possible, as silent as possible.
    Latitude: 57º36' Highlands, Scotland

  11. #61
    mtbr member
    Reputation:
    Join Date
    Feb 2011
    Posts
    882
    Quote Originally Posted by meltingfeather View Post
    Well put, and I don't disagree.
    However, I don't think a Cleland or fat bike should be a license to do whatever you want. Sustainability is key, which sometimes means using trails.
    Rants about access are misplaced, or at least way off topic.
    A rant? True

    Way off topic? Depends upon your perspective.

    Can you see it as a call for you to marry your passion for nature with your profession to say yes instead of no? You are a civil engineer, are you not? People with such skills are needed to strike a balance to the where, when, how much, and why.

    Velobike has gone to some amount of trouble to post pictures of evidence on a thread on the fat bike fourm, I forget the title, perhaps he will chime in with it, it could be useful to you should you choose. In any even it was maybe about a year ago last spring?

  12. #62
    transmitter~receiver
    Reputation: meltingfeather's Avatar
    Join Date
    May 2007
    Posts
    8,953
    Quote Originally Posted by Sand Rat View Post
    A rant? True

    Way off topic? Depends upon your perspective.
    Not that I wasn't to begin with. Topics like these tend to drift that way.
    I think Cleland's are cool bikes... and I certainly appreciate the rides/riders depicted here and what they do.

    Quote Originally Posted by Sand Rat View Post
    Can you see it as a call for you to marry your passion for nature with your profession to say yes instead of no? You are a civil engineer, are you not? People with such skills are needed to strike a balance to the where, when, how much, and why.
    Absolutely. That is why I became a civil engineer in the first place. Civil engineering is at the interface of civilization and the natural environment. As I said, sustainability is key... at least to me. I was just countering the point that a Cleland is a license to go and do whatever you want... because deer to it or the evil corporate-government complex robbing the populous of it's own lands or whatever you can come up with aren't mitigating factors in my mind.

    Quote Originally Posted by Sand Rat View Post
    Velobike has gone to some amount of trouble to post pictures of evidence on a thread on the fat bike fourm, I forget the title, perhaps he will chime in with it, it could be useful to you should you choose. In any even it was maybe about a year ago last spring?
    I don't disagree that fat bikes cause relatively little damage... never even took up that topic.
    I have to admit, "exclusionary dictums of the urban eco-aesthetes of wealthy western countries" is hilarious like an internet fail video... and, once again, absurd. Good for a laugh, but not something I want to waste my time reading on a regular basis... very much like Grant Petersen's contributions to the annals of e-cycling.
    I'm not sure which narrow band of his lineage Velobike is evoking. Life forms have been expelling eachother since the dawn of time and no doubt every one of us has ancestors on both sides of an emotionally charged expulsion story. There are just so many layers of irony to enjoy in that one smug statement.
    Originally I responded to two counts: the attitude that one should be able to do whatever one pleases if mounted on a fat bike/Cleland, and the statement that people who want to go fast should be at the velodrome.
    Last edited by meltingfeather; 09-22-2012 at 10:52 PM.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
    29er Tire Weight Database

  13. #63
    mtbr member
    Reputation: Velobike's Avatar
    Join Date
    Jun 2007
    Posts
    6,332
    Quote Originally Posted by meltingfeather View Post
    ...I have to admit, "exclusionary dictums of the urban eco-aesthetes of wealthy western countries" is hilarious like an internet fail video... and, once again, absurd...

    Originally I responded to two counts: the attitude that one should be able to do whatever one pleases if mounted on a fat bike/Cleland, and the statement that people who want to go fast should be at the velodrome.
    And there I was smugly thinking that that cap fitted you really well, perhaps a bit tight because you sound a bit cranky to me, what with all the personal cracks.

    But let's leave the ideological discussion to those who actually live a pure eco-life*, and concentrate on the Cleland bike.

    The trailpark/velodrome remark was because there was an implied criticism of the potential speed of the Cleland bike, so I responded with a sort of an ironic reductio ad absurdum, to illustrate that speed on mtbs is best enjoyed on hardened surfaces. My bad.

    As far as an "attitude that one should be able to do whatever one pleases if mounted on a fat bike/Cleland", I don't recall seeing that mentioned. It's not do, it's go. There's no such thing as wilderness here. Every square foot of the country has had human presence at some stage, the empty land is actually depopulated areas. Our general ethic is leave it as you found it, we're raised with that, and we teach our kids that. I spend a lot of time in the mountains in Scotland and I have seen no evidence that our open access laws for bicycles have caused any problems.

    Hence my statement that a fat tyred Cleland style bike would probably be the ultimate off track bicycle.






    *I've no idea what a pure eco-life may be, but I suspect using a car, living in a 1st world urban environment, consuming goods transported vast distances, and having the leisure time to play with bikes, is not it.
    As little bike as possible, as silent as possible.
    Latitude: 57º36' Highlands, Scotland

  14. #64
    Natural Born Killer
    Reputation: nemhed's Avatar
    Join Date
    May 2010
    Posts
    370
    All thread de-railment aside, I find the Cleland design fascinating from more of a "bicycle as practical transportation" standpoint versus a "weekend toy/exercise equipment" standpoint. Of everything I've read in this thread, one of the factoids I'm most surprised about is the 80% rearward weight bias. I'd love to get a chance to ride one in it's "natural environment" but alas in my part of "the middle" (read flyover state) we don't usually see things this interesting in the local bike shop or on the local trails. Again from a design standpoint, it's interesting to see how things evolve when not overly influenced by outside forces, or sort of a divergent evolution so to speak. Just from looking at one I would call it more of a flat land bike, although I'm sure that's not the case. There are "hills" in Great Britain. It also looks like the toe overlap with the front tire might drive me crazy. Sadly I'll probably never know for sure.
    Quote Originally Posted by Skrufryder View Post
    Silly rabbit Jack Daniel drinking donkey kissing caterpiller

  15. #65
    mtbr member
    Reputation:
    Join Date
    Oct 2008
    Posts
    221
    Quote Originally Posted by nemhed View Post
    All thread de-railment aside, I find the Cleland design fascinating from more of a "bicycle as practical transportation" standpoint versus a "weekend toy/exercise equipment" standpoint.
    For me the most universally important aspect of the Cleland design is improved comfort and safety. This is because these aspects could encourage a whole new demographic to cycle off-road. Namely those who like the idea of cycling but don;t enjoy being uncomfortable whilst doing so. We do get reports from cyclists from all over the world who have made their own bikes influenced by aspects of the Cleand design. Most rewarding are the tales of everyday cyclists in third world countries.

    Quote Originally Posted by nemhed View Post
    Of everything I've read in this thread, one of the factoids I'm most surprised about is the 80% rearward weight bias.
    The rearwards weight bias is variable. Lean backwards off the saddle and it could be 95%. Stand forwards with your upper body in front of the handle bars and it could be only 20%. Even in the saddle there is a good degree of flexibility with 80% being the number you get when you sit bolt upright with no weight on your arms.

    Quote Originally Posted by nemhed View Post
    I'd love to get a chance to ride one in it's "natural environment" but alas in my part of "the middle" (read flyover state) we don't usually see things this interesting in the local bike shop or on the local trails. Again from a design standpoint, it's interesting to see how things evolve when not overly influenced by outside forces, or sort of a divergent evolution so to speak.
    We don't consider the design as our intellectual property and would cooperate with any manufacturers who wanted to make them. A UK manufacturer was intending to re-manufacturer them a couple of years ago but this never happened. Hopefully one day they will be manufactured, and people will be able to try them for themselves.

    Quote Originally Posted by nemhed View Post
    Just from looking at one I would call it more of a flat land bike, although I'm sure that's not the case. There are "hills" in Great Britain.
    Despite the flatland looks Clelands have the reputation of being excellent climbers.This has its own counter-intuitive explanation in physics the result of which is they can climb 44% slopes for as long as the riders legs and lungs can cope. Their very well moderated brakes also make them good at descending. If things go wrong you can just jump off the back.Cleland: The original big wheeled off-road bicycle?-r0012768.jpg

    Quote Originally Posted by nemhed View Post
    It also looks like the toe overlap with the front tire might drive me crazy. Sadly I'll probably never know for sure.
    I've never noticed this to be a problem. Maybe I have just got used to it?

  16. #66
    mtbr member
    Reputation: smilinsteve's Avatar
    Join Date
    Jul 2009
    Posts
    8,613
    Interesting to me how even the most obvious (in my mind) truths become contentious.
    Funny this world we live in. For example, I remember when air pollution was just bad. I never imagined I'd live in a time where there was a "pro-pollution" stance.

    But back to the original off-topic topic. Is it so hard to imagine a good reason for different levels of access rules for different places with different levels of wilderness and the sensitivities that go with it?

    I had some friends in Alabama who laughed at my conservative ways (yes, it is liberals who want to conserve! Ironic eh?)
    Clear cutting the thick woods down there, cutting down hundred year oak trees because they needed firewood, I mentioned something about what a shame that was.
    "ha ha. The land is here to use! "
    or maybe they said something like
    Come now...if man was not part of nature, nature left to itself...dies. Nothing would stay the same. Nature is a process of life unto death followed by rebirth. Nature is a part of creation, it is not GOD, to be held above man.


    The funny thing about those guys, was that they live in a place that is ugly. Completely f%cked up.
    They drive 4 hours to where they can get to a piece of woods they can hunt on, and that is just a tree farm. Trees in rows. I'm not kidding.
    Maybe they don't see the irony because they have never been to a truly beautiful place in its natural state. They don't see the irony, but I hope you do.

  17. #67
    mtbr member
    Reputation: smilinsteve's Avatar
    Join Date
    Jul 2009
    Posts
    8,613



    I picture really is worth a thousand words, isn't it?
    It looks to me like there are trails in the area, but this guy decides he wants to ride down on the hill with no trail. It sure looks like fun to do that.
    And if he was the only one to do it, it probably wouldn't be too much of a problem.
    But if lots of people see how cool that hill looks to ride down, what happens? The plant life dies under the tire tracks, the dirt is slightly depressed, forming water channels, the rain starts forming gully's, etc. After this hill becomes a popular mountain bike destination for a couple of seasons, it looks like an eroded, dead, scarred up mess. It might even become unridable, in which case it would be ok to go find another hill, and start over, right?


    Is that really a better option than having a trail down that hillside that people can enjoy while keeping the surrounding environment relatively stable and undamaged?

  18. #68
    mtbr member
    Reputation:
    Join Date
    Oct 2008
    Posts
    221
    smilinsteve,

    You are indeed correct and as a result I would refuse to identify that location if anyone asked. Of course someone could always recognize the location from the photo and go there with the intention of riding down this slope. In fact I first discovered this slope when I saw a large group of mountain bikers trying and failing to ride down it. They either went over the handle bars of chickened out. The slope is not at all smooth and steeper than it looks in the photo. And there is no run out at the bottom so even the downhill bikes would have nowhere to go except into the trees. The dilemma is that they could ride down if they had Clelands. But is this an argument for Keeping the Cleland design a secret?

  19. #69
    transmitter~receiver
    Reputation: meltingfeather's Avatar
    Join Date
    May 2007
    Posts
    8,953
    Quote Originally Posted by Velobike View Post
    And there I was smugly thinking that that cap fitted you really well, perhaps a bit tight because you sound a bit cranky to me, what with all the personal cracks.
    lol... from the guy who brought the "personal crack." my comments were solely in relation to yours... you are the one who used the label "eco-asthetete" and implied some sort of skewed hiprocrisy.
    by all means, though.
    Quote Originally Posted by Velobike View Post
    The trailpark/velodrome remark was because there was an implied criticism of the potential speed of the Cleland bike, so I responded with a sort of an ironic reductio ad absurdum, to illustrate that speed on mtbs is best enjoyed on hardened surfaces. My bad.
    this comment would have been the end of the discussion. since smilinsteve, who you were addressing, said nothing about speed, it seemed odd and as i said, absurd.
    i guess i don't "know" you well enough.

    Quote Originally Posted by Velobike View Post
    As far as an "attitude that one should be able to do whatever one pleases if mounted on a fat bike/Cleland", I don't recall seeing that mentioned. It's not do, it's go. There's no such thing as wilderness here. Every square foot of the country has had human presence at some stage, the empty land is actually depopulated areas. Our general ethic is leave it as you found it, we're raised with that, and we teach our kids that. I spend a lot of time in the mountains in Scotland and I have seen no evidence that our open access laws for bicycles have caused any problems.
    That's great, and I think leave it as you found it is all either of us alluded to. Some places you can do that by riding a fat bike across hill and dale, some places you can't. I thought it might be a context thing. I was just pointing out, as smilinsteve was, that it is context dependent, which you seemed to reject. both of us qualified the need for trails as being context dependent (e.g., "some areas," etc.).

    Quote Originally Posted by Velobike View Post
    Hence my statement that a fat tyred Cleland style bike would probably be the ultimate off track bicycle.
    It is... in places where such a bike does not cause irreparable harm. Your statements and those about "elevating nature to the level of God" or whatever were in no way qualified... and to me conveyed the sentiment that humans should be able to go where they please at their whim because deer and air and water do.

    i think we've beat this enough, eh? my apologies if I offended. cranky I am not.

    let's see more Cleland pics!






    *I've no idea what a pure eco-life may be, but I suspect using a car, living in a 1st world urban environment, consuming goods transported vast distances, and having the leisure time to play with bikes, is not it.[/QUOTE]
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
    29er Tire Weight Database

  20. #70
    mtbr member
    Reputation:
    Join Date
    Sep 2012
    Posts
    50
    Smiling Steve: whilst I am vaguely sympathetic to your concerns, in this country at any rate, your concerns are unfounded:
    a) The vast majority of mountain bikers don't explore; they prefer to stay on well-ridden clear firm tracks.
    b) Property law and access rights mean that there are fences and hedges everywhere, rarely can you ride off trail for more than half a mile before having to stop and lift your bike over a fence or stile; not very appealing to the average rider.
    c) Much of the UK is intensively managed; to find these areas of interest usually requires a fair amount of research, and the vast majority can't be bothered.
    d) What Graham didn't mention is that the none of the mountain bikers in the group he was with would dare to ride down that slope; it's a lot steeper than the photo shows.
    e) You see that scar up the other side of the valley; made by sheep.
    f) When the farmer wants to check his sheep, he drives up in a 4X4.
    g) Most off-trail terrain is simply too difficult/boring for the average mountain biker.
    h) Getting trails built/made is not at all easy; to make it a worthwhle distance, it often has to cross the land of several landowners, rarely are they all that keen to allow it.
    So, although you have a case, the actual amount of damage that is likely to be caused by Cleland and Fat Bike explorers is very small indeed, and most unlikely to attract hoards of mountain bikers.

    Off topic, off trail, off piste ~ typically Cleland

  21. #71
    mtbr member
    Reputation:
    Join Date
    Feb 2011
    Posts
    882
    Thanks Graham for addressing the questions poised by Nemhed.

    For those with concerns with toe overlap because of the short wheelbase there are things that can be helpful.

    1 A wider BB

    2 Or, you may find yourself as in my case. I ride a 89 Fisher (full rigid) with toe clips until about a month ago. While on a ride I turned my attention to the slight, but not bottersome stress at my knees.I removed them. Low and behold, my toes turned away from the centerline and my stance upon the pedals was somewhat wider. Yeah, I walk like a duck!

    3 Lower the BB somewhat, to place your toes at a point lower and further from the tire. Should this not at first seem like the direction you would choose to go, with the advent of Srams XX1 you could find yourself willing to trade increased chainwheel clearance for a loss of pedal clearance?

    @ Graham or Geoff...would you care to post more of the geo stats on your design? I have tried to quess some, but nothing beats the facts, would give me and others a starting point from which to apply your design freatures to fit ourselves. I have not found them posted on your site, did I miss?

  22. #72
    mtbr member
    Reputation:
    Join Date
    Sep 2012
    Posts
    50
    Quote Originally Posted by Sand Rat View Post
    Thanks Graham for addressing the questions poised by Nemhed.

    For those with concerns with toe overlap because of the short wheelbase there are things that can be helpful.

    1 A wider BB

    2 Or, you may find yourself as in my case. I ride a 89 Fisher (full rigid) with toe clips until about a month ago. While on a ride I turned my attention to the slight, but not bottersome stress at my knees.I removed them. Low and behold, my toes turned away from the centerline and my stance upon the pedals was somewhat wider. Yeah, I walk like a duck!

    3 Lower the BB somewhat, to place your toes at a point lower and further from the tire. Should this not at first seem like the direction you would choose to go, with the advent of Srams XX1 you could find yourself willing to trade increased chainwheel clearance for a loss of pedal clearance?

    @ Graham or Geoff...would you care to post more of the geo stats on your design? I have tried to quess some, but nothing beats the facts, would give me and others a starting point from which to apply your design freatures to fit ourselves. I have not found them posted on your site, did I miss?
    I think this refers to the AventuraTT, a profile of which appears on the home page of the Cleland website.
    Look closely; the toe does not overlap the wheel/tyre; it overlaps a very flexible mudguard extension. It is therefore not an issue.
    This overlap exits because the frame used for this prototype was bought off-the-shelf.
    A purpose-built fame design would have the bottom bracket axis further to the rear, which would eliminate this insignificant aspect.

    Do you actually mean a wider BB, or do you really mean Q factor?
    In view of my above comments, lowering the bottom bracket is neither desirable or necessary.
    Note also: swing pedals effectively lower the rotational movement of the feet to more or less the average bottom bracket height.

    So, look again at that profile, more carefully this time. If you click on it, you get a larger image, and if you click again, you get a magnifier for an even closer look.

    I do apologise for there being no concise description of the AventuraTT on the Cleland website. If I find time, soon I'll create a special page to cover a complete and detailed specification.

    As requested, and not un-connected to this reply, here are some more Cleland photos; these appeared in another MTBR thread recently. You'll notice I never clean my bike; I don't need to.
    On the subject of more Cleland photos; have you clicked on the Flickr link to the right of the homepage? There are loads of photos, several with comments and technical notes.
    Attached Thumbnails Attached Thumbnails Cleland: The original big wheeled off-road bicycle?-dscf2767.jpg  

    Cleland: The original big wheeled off-road bicycle?-dscf2770.jpg  

    Cleland: The original big wheeled off-road bicycle?-dscf2773.jpg  

    Cleland: The original big wheeled off-road bicycle?-dscf2774.jpg  

    Cleland: The original big wheeled off-road bicycle?-dscf2775.jpg  


  23. #73
    Natural Born Killer
    Reputation: nemhed's Avatar
    Join Date
    May 2010
    Posts
    370
    GrahamWallace, thanks for addressing my post. From my personal experience with my own explorer/commuter bike I would find clipping the mud flap with my toes annoying, but that's just me. I would shorten it up a bit. Actually touching the tire would get beyond annoying. Looking at those drive train pictures makes me feel like I'm looking at some alternate universe bike with the elliptical chainrings, square water bottle, and offset pedals. But I appreciate the rational for all the the tech details. I also appreciate the "why clean it if its just going to get dirty right way" ethic!
    Quote Originally Posted by Skrufryder View Post
    Silly rabbit Jack Daniel drinking donkey kissing caterpiller

  24. #74
    mtbr member
    Reputation:
    Join Date
    Sep 2012
    Posts
    50
    Well, in practice, your toes don't actually touch it while pedalling, except on very rare occasions.
    The point you really have to consider is that it is of optimal size and length to serve its principle function of protecting the chain from stuff thrown up by the front wheel; shorten it and it no longer functions.
    The Cleland design is full of compromises in its ethos of functionality, and this is but one; a very small annoyance pays very big dividends.
    The non-cleaning ethic is another aspect of its functionality; this bike is built to be ridden, not to be cleaned.
    I recently read a report about a mountain bike enduro where each lap was about 7 miles. Due to the mud on the course, the riders had to replace disc pads every three or so laps, and the derailleurs had to be cleaned down every lap. To my mind, that's not functionality; I suppose a Cleland would have done quite well, but not with me riding it!
    Your description of your bike as explorer/commuter is excellent; I use the Aventura for utility as well as exploration, with its mudguards, chainchoobz, bash plate as trouser guard and upright stance, you can ride it in everyday clothes. Functionality again...

  25. #75
    transmitter~receiver
    Reputation: meltingfeather's Avatar
    Join Date
    May 2007
    Posts
    8,953
    Quote Originally Posted by GeoffApps View Post
    Smiling Steve: whilst I am vaguely sympathetic to your concerns, in this country at any rate, your concerns are unfounded:
    a) The vast majority of mountain bikers don't explore; they prefer to stay on well-ridden clear firm tracks.
    b) Property law and access rights mean that there are fences and hedges everywhere, rarely can you ride off trail for more than half a mile before having to stop and lift your bike over a fence or stile; not very appealing to the average rider.
    c) Much of the UK is intensively managed; to find these areas of interest usually requires a fair amount of research, and the vast majority can't be bothered.
    d) What Graham didn't mention is that the none of the mountain bikers in the group he was with would dare to ride down that slope; it's a lot steeper than the photo shows.
    e) You see that scar up the other side of the valley; made by sheep.
    f) When the farmer wants to check his sheep, he drives up in a 4X4.
    g) Most off-trail terrain is simply too difficult/boring for the average mountain biker.
    h) Getting trails built/made is not at all easy; to make it a worthwhle distance, it often has to cross the land of several landowners, rarely are they all that keen to allow it.
    So, although you have a case, the actual amount of damage that is likely to be caused by Cleland and Fat Bike explorers is very small indeed, and most unlikely to attract hoards of mountain bikers.

    Off topic, off trail, off piste ~ typically Cleland
    very informative, thanks. this makes a lot of sense, and it is now easy to see how context is so determinant.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
    29er Tire Weight Database

  26. #76
    mtbr member
    Reputation:
    Join Date
    Oct 2008
    Posts
    221
    Ultimately there can be be a certain irony to riding a Cleland over challenging terrain. This is the fact that sometimes you may be able to make faster progress on foot, without using a bike at all. Or even by carrying the bike over the worst sections of trail.

    But the ethos of reaching the destination and not having to turn back whatever confronts you is strong. A kind of survivalist mentality where the worse the trail conditions or weather, the more enjoyable the riding is. Conversely on warm dry Summer's days with smooth easy trails a Cleland can feel somewhat out of place and over engineered with its fenders, guards, elliptical gears, hub brakes and low pressure tires. All that remains of use is the comfortable easy to balance tall riding position.

    Does this make me leave the Cleland at home on such days and make the logical choice of using my carbon fiber full suspension XC bike. Well not very often. I would miss the standing out of the saddle standing bolt upright on the pedals, my head 7 feet plus above the ground whilst the handle bars oscillate backwards and forwards with rise and fall of the terrain. Just like the way children love to ride there BMX bikes.

    If you find it difficult to imagine how a Cleland rides. Just think BMX with very big wheels, and you wont be that far off.

  27. #77
    Start slow and taper off
    Reputation:
    Join Date
    Feb 2004
    Posts
    790
    Quote Originally Posted by GrahamWallace View Post
    Here is a video that shows a modern Cleland Aventura TT riding along another stream.

    I'm not knocking the bikes, but I honestly don't see anything in that video that I haven't done with my 26" (or now with my 29'ers) bikes,including the stream riding.

    The part where he rides over the log is just plane silly. They slow the video down as if getting over the little log is a big accomplishment.

    And either the rider is really twitchy in his riding style, or the bike makes for a twitchy riding style.
    My Artwork

    Hard words break no bones, fine words butter no parsnips.

  28. #78
    mtbr member
    Reputation:
    Join Date
    Sep 2012
    Posts
    50
    Quote Originally Posted by neveride View Post
    I'm not knocking the bikes, but I honestly don't see anything in that video that I haven't done with my 26" (or now with my 29'ers) bikes,including the stream riding.

    The part where he rides over the log is just plane silly. They slow the video down as if getting over the little log is a big accomplishment.

    And either the rider is really twitchy in his riding style, or the bike makes for a twitchy riding style.
    The 4th paragraph on the home page of the Cleland website says:
    "The Cleland Aventura can do some things more easily or efficiently than a mountain bike because it follows function before form. By the same token, a mountain bike can do some things an Aventura can’t; both do similar things, but in slightly different ways."

    For every mountain bike rider who looks at the little log being ridden over, there are (nominally) 9,999 people who would think it a major accomplishment. The video is more aimed at the 9,999. I suspect that most mountain bike riders realise this.

    Below the water's surface are slippery slimy rocks and stones, sandy patches and hollows. Because of the angle of the sunlight, these are impossible for the rider to see. When the front wheel hits them, the steering twitches. As an experienced rider, including stream riding, I would have thought you could have figured this out for yourself.

  29. #79
    mtbr member
    Reputation: Bigwheel's Avatar
    Join Date
    Jan 2004
    Posts
    2,177
    Yawn.
    A bike by any other name is still a bike.

  30. #80
    mtbr member
    Reputation:
    Join Date
    Sep 2012
    Posts
    50
    Sleep well...

  31. #81
    Start slow and taper off
    Reputation:
    Join Date
    Feb 2004
    Posts
    790
    Quote Originally Posted by GeoffApps View Post
    The 4th paragraph on the home page of the Cleland website says:
    "The Cleland Aventura can do some things more easily or efficiently than a mountain bike because it follows function before form. By the same token, a mountain bike can do some things an Aventura can’t; both do similar things, but in slightly different ways."

    For every mountain bike rider who looks at the little log being ridden over, there are (nominally) 9,999 people who would think it a major accomplishment. The video is more aimed at the 9,999. I suspect that most mountain bike riders realise this.

    Below the water's surface are slippery slimy rocks and stones, sandy patches and hollows. Because of the angle of the sunlight, these are impossible for the rider to see. When the front wheel hits them, the steering twitches. As an experienced rider, including stream riding, I would have thought you could have figured this out for yourself.
    Websites say a lot of things--we call that marketing. So lets leave that where it lies.

    I somehow doubt the 9,999 riders that this video is aimed at are regularly in the habit of thinking "damn, if I only had a different, more purpose built bike, then I'd decide to ride up this stream". So i think maybe there is a lot of confusion about who this video is aimed at. I mean, I doubt someone who thinks getting over that rather small log is a big accomplishment is also the same person who regularly wants to ride up streams.

    The twitchy-ness I was referring to was not during the stream ride--that I would expect to be twitchy. It is the rest of the video--on the non-stream trails, where the bike and rider appear twitchy. Places that should be smooth and flowing I suspect a lot has to do with the gear the rider is in, as well as the layout of the bike.
    My Artwork

    Hard words break no bones, fine words butter no parsnips.

  32. #82
    mtbr member
    Reputation:
    Join Date
    Feb 2011
    Posts
    882
    [QUOTE=GeoffApps;9715648]
    Do you actually mean a wider BB, or do you really mean Q factor?
    QUOTE]

    Sorry for the delay, yes a wider Q factor, I was thinking a 100mm BB and 4-5" tires.

    At 65 a more upright position has its appeal. My currant bike, a 26er has,the best I can measure a 625mm FC and a 130 stem. The Surly Moonlander with 30" tires has a FC of 623.4 and a stem of 90 in size small.

    If I apply your idea on position, I should come close? And any concerns about toe overlap are dealt with. I am also thinking that in reguards to your stats on geo, the position over the pedals overides the others? My currant bike, I am told has a 73.5* STA,
    Close to yours?

    By the way Graham...you did not say just how you got back up that hill...through lots of effort...no matter the method!

  33. #83
    mtbr member
    Reputation:
    Join Date
    Oct 2008
    Posts
    221
    What do mountain bikers who have ridden alongside or a test ridden a Cleland think?
    Cleland: The original big wheeled off-road bicycle?-dscf5084w.jpg

    Bear in mind that an unusual bike like a Cleland takes quite a while to get used to. So the quotes below are just initial reactions.

    These are are all the Cleland related comments from the ride report of a group of UK mountain bikers, who Geoff joined for a recent days ride in the Scottish Hills.

    The full report can be found here from page 7 onwards:
    Retrobike National Series Rd 5: Tweed Valley ~ AFTERMATH pg7 | Retrobike

    "Great to meet several new faces and several I'd met before.
    It was also a real pleasure and an honour to have Geoff Apps along on his prototype Cleland Aventura. Really fantastic bit of design and engineering and a really nice person to chat with. Pretty handy on a bike too".

    "The upside was I got a few chances to chat with Geoff and hear some of his fascinating ideas about cycling techniques. Everyone that tried his bike were quite taken with it, Mikee in particular".

    "Lord apps ...
    been thinking of how to word my apprasial of sir geoff's bicycle
    went thru the engineering slant then the flowery prose
    in the end i thought id tell it as it is
    i caught up with geoff on one of the early climbs ,i complimented him on the bike , and his reply included the words "want "and" go" in it
    jeff looks a bit smaller than me , but it seemed to fit fine , so when i mastered the technique of mounting the steed i was off (geoff later gave a demo of the moving off bit)
    as an engineer i'm not a sceptic with most things ,including this bike
    but i was not prepared for the experience
    the nearest i can get to is , you know that time when you've packed up
    your rear wheel drive car in the wet field and your trying to get to the exit road slippy slidey no traction type thing
    then some idiot in a landy is driving about up and down thing just because
    they can ?
    thats what the clellands like ,i rode it up the trail a bit then rode over a grassy bit between 2 trails , with no problems , very little body shift is required you just turn the pedals and it goes up ,well anything
    the (i assume )chris bell egg rings went un-noticed until someone pointed
    them out , obviously done right ,like the rest of the bike
    as for speed on it ,well i dont know as geoff wanted it back for the down bits , but he looked smooth and fast on the bits i saw
    and the "lovely hill" as he called it ,i missed him out climbing everyone
    all in a lovely fella and a cracking bike , i hope you make some more sir

    so i met a legend , rode his bike ,and found a new hero
    top day out i'd say "

    "It was great treat to meet Geoff and hear all the reasoning behind each detail on this amazingly capable machine. I didnt get to ride it unfortunatley but I did note that not one person went away unimpressed"

    "Some interesting bikes but Geoffs Clelland definetly stole the show".

    I stuck with Geoff and chatted about his bike. He was having a bit of difficulty with his breathing (smoking too much was his excuse but I hope I'm still riding at 63!!) so we walked up a bit together. He let me ride his bike up one of the steep bits and I have to say after 1 pedal turn I could see what is was all about. The unbelievable grip, smoothness and just plain ease of riding was astonishing. More later......

    "Geoff let me ride his bike quite a bit and I think he thought I'd pinched it as I went off on my own a fair distance while he pushed my bike - sorry Geoff, but it was your own fault for designing such an awesome addictive machine!!"

    "When I rode the Cleland I wasn't sure about it downhill, but Geoff soon showed it was excellent there too as he shot away from me like a bullet on the first slippery muddy rocky downhill. I just couldn't believe it. he just made it look so easy while I was slip-sliding away..... "

    "Good also to meet Geoff Apps having read plenty about the man and his bikes over the years. Good chap and handy rider too".
    Cleland: The original big wheeled off-road bicycle?-inners02_127.jpg
    Last edited by GrahamWallace; 10-03-2012 at 03:33 PM. Reason: Typos

  34. #84
    mtbr member
    Reputation:
    Join Date
    Sep 2012
    Posts
    50
    There I was demonstrating how easy it is on an Aventura to pick your nose without having to dismount.

  35. #85
    mtbr member
    Reputation: smilinsteve's Avatar
    Join Date
    Jul 2009
    Posts
    8,613
    I'm still trying to wrap my head around the idea of higher COG=more stable? Inverted pendulum? Mind boggling.

  36. #86
    mtbr member
    Reputation:
    Join Date
    Oct 2008
    Posts
    221
    Quote Originally Posted by Sand Rat View Post

    @ Graham or Geoff...would you care to post more of the geo stats on your design? I have tried to quess some, but nothing beats the facts, would give me and others a starting point from which to apply your design freatures to fit ourselves. I have not found them posted on your site, did I miss?
    This may help. It's the drawing for a 650b Cleland I had made in 1988. It has a 100mm wide bottom bracket and about 40mm clearance between frame/forks and tires so 29er wheels should fit. I'm 6 foot two inches tall so the frame would need scaling down for smaller riders. There are modern bikes with similar geo stats. And a small sized frame size will give you the shorter wheelbase required.
    Cleland: The original big wheeled off-road bicycle?-highpath_322_131.jpg

  37. #87
    mtbr member
    Reputation:
    Join Date
    Oct 2008
    Posts
    221
    Quote Originally Posted by smilinsteve View Post
    I'm still trying to wrap my head around the idea of higher COG=more stable? Inverted pendulum? Mind boggling.
    It is!

    But to describe it in a different way to earlier explanations...

    As the bicycle falls its center of mass accelerates, due to gravity, and describes a 90 degree semicircular arc until it hits the ground.

    The taller the bike the longer the circular path taken by the mass and so the slower the fall. A 1m center of mass would take half the time to fall of a 2m center of mass.

    When the bike and rider are balanced, gravity is not rotating their center of mass but pulling it straight downwards. The more the bicycle leans the stronger the rotational pull of gravity and so the faster the acceleration.

    A tall object though initially falling slower will actually be falling faster when it hits the ground.

    In practice there are two crucial angles for a given height of bike:

    The angle at which the bicycle cannot be rebalanced by swerving at a given speed.

    And size of the angle from the vertical that a bike can be balanced without any overt use of the steering. (The track stand angle or riding on sheet ice angle)

    Here is video that shows why a bicycle is a form of inverted pendulum.

    One robot wheel moves from side to side just like the front wheel of a moving bicycle weaves from side to side as you steer. The other wheel remains stationary in a similar way to the rear wheel of a bike. What it does not show is that increasing the height of the robot/pendulum would make it rock more slowly and so give the robot more time to react.
    Inverted Pendulum - YouTube
    When you think about it, long ordinary pendulums also swing more slowly than short ones.


    I hope this helps?
    Last edited by GrahamWallace; 09-24-2012 at 04:22 PM.

  38. #88
    mtbr member
    Reputation: smilinsteve's Avatar
    Join Date
    Jul 2009
    Posts
    8,613
    Quote Originally Posted by GrahamWallace View Post
    It is!

    But to describe it in a different way to earlier explanations...

    As the bicycle falls its center of mass accelerates, due to gravity, and describes a 90 degree semicircular arc until it hits the ground.

    The taller the bike the longer the circular path taken by the mass and so the slower the fall. A 1m center of mass would take half the time to fall of a 2m center of mass.

    When the bike and rider are balanced, gravity is not rotating their center of mass but pulling it straight downwards. The more the bicycle leans the stronger the rotational pull of gravity and so the faster the acceleration.

    A tall object though initially falling slower will actually be falling faster when it hits the ground.

    In practice there are two crucial angles for a given height of bike:

    The angle at which the bicycle cannot be rebalanced by swerving at a given speed.

    And size of the angle from the vertical that a bike can be balanced without any overt use of the steering. (The track stand angle or riding on sheet ice angle)

    Here is video that shows why a bicycle is a form of inverted pendulum.

    One robot wheel moves from side to side just like the front wheel of a moving bicycle weaves from side to side as you steer. The other wheel remains stationary in a similar way to the rear wheel of a bike. What it does not show is that increasing the height of the robot/pendulum would make it rock more slowly and so give the robot more time to react.
    Inverted Pendulum - YouTube
    When you think about it, long ordinary pendulums also swing more slowly than short ones.


    I hope this helps?
    Thanks. That's a good explanation. But, on the other hand

    For any given angle of the bicycle and rider, the moment on the pivot point (the contact patch) is greater when the COG is higher. So it takes more force to stabilize the bike from any given lean angle.
    It seems to me that if you lower the COG, you are able to have more lean with less likelihood to fall over, since distance from the COG to the pivot is smaller (lower torque)..

    How does your explanation fit into the following observation:

    A tightrope walker uses a weighted pole, curved downward, not upward, to stabilize himself. The length of the pole increases his moment of inertia, which stabilizes him against small forces that would move him away from equilibrium. Meanwhile, the lower COG means deviations from center have less of a torque on him that would cause him to fall. In fact, if you could lower the COG below the pivot point, as is possible with the tightrope walker, deviations from center create a torque that tends to right the walker.

    So in this case, clearly a low COG is better. What is different about the bicycle?

  39. #89
    mtbr member
    Reputation:
    Join Date
    Feb 2011
    Posts
    882
    Wow, Graham...Thanks!

    At first look it seems as if currant bike if fitted with your idea of stem and bar placement would require little change. Perhaps a Syntace VRO stem in small, (55-105 in adjustment) with larger clamps to extend the range might be workable.

    Of course, if done to my currant bike, it would lack some of your other features. But it does allow me to better place in my mind your concept.

    Thanks again!

  40. #90
    mtbr member
    Reputation: smilinsteve's Avatar
    Join Date
    Jul 2009
    Posts
    8,613
    In practice there are two crucial angles for a given height of bike:

    The angle at which the bicycle cannot be rebalanced by swerving at a given speed.

    And size of the angle from the vertical that a bike can be balanced without any overt use of the steering. (The track stand angle or riding on sheet ice angle)
    I'm not sure about the first angle, but the second angle should be greater when the COG is lower, it seems to me.

  41. #91
    mtbr member
    Reputation: Velobike's Avatar
    Join Date
    Jun 2007
    Posts
    6,332
    Here's a wee experiment.

    Take a thin rod about 12" long, place a weight at one end.

    Balance it on your fingertip with the weight down. Now move your finger quickly to one side while trying to keep the rod balanced. Odds are you won't manage to keep it balanced even though the CoG is low.

    Now do it with the weight at the top. I'll bet you'll find it easier to balance even though the CoG is high.

    That's how I envisage what Graham is explaining, a high CoG makes it easier for the rider to handle sudden lateral displacements of the bikes contact patch.
    As little bike as possible, as silent as possible.
    Latitude: 57º36' Highlands, Scotland

  42. #92
    Natural Born Killer
    Reputation: nemhed's Avatar
    Join Date
    May 2010
    Posts
    370
    In even more practical terms; in a side by side comparison between a Cleland and a recumbent in all riding conditions, which would be the better bicycle in most conditions? My money would be on the Cleland. Low CG is not the be all end all when it comes to two wheels vehicles. Whether a Cleland makes a better off-road bicycle than say a more "common" XC bike probably comes down to personal taste and riding styles, rather than the relative CG of the two bikes with their accompanying riders.
    Quote Originally Posted by Skrufryder View Post
    Silly rabbit Jack Daniel drinking donkey kissing caterpiller

  43. #93
    mtbr member
    Reputation:
    Join Date
    Oct 2008
    Posts
    221
    Before you read my answers I recommend you check out this video on Rotational Dynamics: Angular Acceleration and Rotational Inertia.
    Lesson 25 Sample - YouTube

    Quote Originally Posted by smilinsteve View Post
    Thanks. That's a good explanation. But, on the other
    hand

    For any given angle of the bicycle and rider, the moment on the pivot point (the contact patch) is greater when the COG is higher. So it takes more force to stabilize the bike from any given lean angle.
    It seems to me that if you lower the COG, you are able to have more lean with less likelihood to fall over, since distance from the COG to the pivot is smaller (lower torque)..
    Pivot point = Fulcrum

    Effort or Input = the downwards force of gravity or/and the lateral movement of the fulcrum.

    Load = COG

    As a lever mechanism there are some problems here:
    a) We have two inputs one at either end of the lever
    b) We have a fulcrum or fixed pivot which is restrained in two dimensions but not fixed. Therefore it cannot be a fulcrum.
    c)Considering the torque loading at the contact point is pointless as the torque is not applied there but at the COG. Unless you rigidly fix the wheel to the ground?

    I do understand where you are coming from here. A rider can use the inertia of his body weight to move a bicycles mass to the left or right whilst the contact patch acts as a fulcrum. This can indeed help to maintain balance. It's similar to the way a runner balances the rearward movement of their left leg by moving their right arm forwards.



    Quote Originally Posted by smilinsteve View Post
    How does your explanation fit into the following observation:

    A tightrope walker uses a weighted pole, curved downward, not upward, to stabilize himself.
    The pole does not have to curve downwards but will lower the combined COG of man and pole if it does. In inverted pendulum theory height is inversely proportional to acceleration so a lower COG will accelerate faster than a smaller one. However the rotational inertia of the pole would slow down any acceleration.

    Quote Originally Posted by smilinsteve View Post
    The length of the pole increases his moment of inertia, which stabilizes him against small forces that would move him away from equilibrium.
    Yes, Newton's third law of motion is at work here as every clockwise rotation of the pole will cause an equal and opposite anti-clockwise moment of the walker. This is the mechanism that enables him to balance.

    Quote Originally Posted by smilinsteve View Post
    Meanwhile, the lower COG means deviations from center have less of a torque on him that would cause him to fall.
    Whilst small deviations from the center balanced position do create less gravitationally induced torque, it is the rotational inertia of the pole that counters lean. At best effect of the COG height is only to give him more or less time to react.

    Quote Originally Posted by smilinsteve View Post
    In fact, if you could lower the COG below the pivot point, as is possible with the tightrope walker, deviations from center create a torque that tends to right the walker.
    The tightrope walker are two separate but coupled systems. Only when the combined COG is below the rope could balance be maintained without the effects of the relative movement between walker and pole.

    Quote Originally Posted by smilinsteve View Post
    So in this case, clearly a low COG is better. What is different about the bicycle?
    A balanced tightrope walker is indeed a form of inverted pendulum so according to inverted pendulum theory a tall tightrope walker should fall to his death more slowly than a short walker. But according to Newton's third law of motion the the rope would rotate to the left as the walker unbalances to the right. This is the equivalent of an inverted pendulum where the movement at the bottom of the pendulum makes things less stable. Instead of moving to restore the state of balance as is the case with a bicycle.
    For the tightrope to be like a bicycle the rope would have to move in the same direction as the fall.

    Types of inverted pendulum.
    There are two separate models of inverted pendulum here. One with a fixed pivot point where maintaining balance is impossible and the only thing to be learned from this is the physics of how inverted pendulums fall. The other is the inverted pendulum were the pivot can move in 2 dimensions where with the correct countering movement, balance can be restored and maintained.

    The reason in physics as to why a taller bike falls slower are closely related to the reasons why a 29er wheel takes more energy or time to accelerate it up to a given speed. The only difference is the direction of the input force as gravity acts vertically and bicycle wheel drive forces act horizontally.

    The key to understanding this is indeed rotational Inertia, and rotational acceleration.
    Think pirouetting ice skater!

    Alternatively try riding a Penny Farthing. There low speed lateral stability is truly amazing.

    After reading this Bigwheel should sleep very deeply indeed

  44. #94
    Perpetual n00b
    Reputation: dgw2jr's Avatar
    Join Date
    Aug 2011
    Posts
    1,760
    I for one think this thread is pretty BA

  45. #95
    mtbr member
    Reputation: smilinsteve's Avatar
    Join Date
    Jul 2009
    Posts
    8,613
    Quote Originally Posted by Velobike View Post
    Here's a wee experiment.

    Take a thin rod about 12" long, place a weight at one end.

    Balance it on your fingertip with the weight down. Now move your finger quickly to one side while trying to keep the rod balanced. Odds are you won't manage to keep it balanced even though the CoG is low.

    Now do it with the weight at the top. I'll bet you'll find it easier to balance even though the CoG is high.

    That's how I envisage what Graham is explaining, a high CoG makes it easier for the rider to handle sudden lateral displacements of the bikes contact patch.
    Funny, in the video Graham just posted the guy balances a golf club with head up and head down and says its easier with head down, (COG closer to fulcrum, ie. finger)

  46. #96
    mtbr member
    Reputation: smilinsteve's Avatar
    Join Date
    Jul 2009
    Posts
    8,613
    Graham. Thanks for the explanations. Its a really interesting topic to me, and one I haven't thought about much in the past, and haven't had much time to ponder lately. So, I'll have to ponder this some more.

  47. #97
    mtbr member
    Reputation: Ze_Zaskar's Avatar
    Join Date
    Jan 2008
    Posts
    854
    A simple way to explain this issue is with the following concepts:
    -High CG- greater range of stability (angular amplitude) but a stronger and slower input is required to correct it.
    -Low CG- smaller range of stability (angular amplitude) but weaker and faster inputs are required to correct it.

    From a mechanical engineer's point of view, this pretty much sums it

  48. #98
    mtbr member
    Reputation: Velobike's Avatar
    Join Date
    Jun 2007
    Posts
    6,332
    Quote Originally Posted by smilinsteve View Post
    Funny, in the video Graham just posted the guy balances a golf club with head up and head down and says its easier with head down, (COG closer to fulcrum, ie. finger)
    Try it for yourself rather than rely on someone else's opinion.

    A club head is pretty broad, so that's not hard to balance. Try it with something that won't balance because its end is very narrow so it's relying on your dynamic input to stay up.
    As little bike as possible, as silent as possible.
    Latitude: 57º36' Highlands, Scotland

  49. #99
    mtbr member
    Reputation:
    Join Date
    Aug 2012
    Posts
    93
    Quote Originally Posted by Ze_Zaskar View Post
    A simple way to explain this issue is with the following concepts:
    -High CG- greater range of stability (angular amplitude) but a stronger and slower input is required to correct it.
    -Low CG- smaller range of stability (angular amplitude) but weaker and faster inputs are required to correct it.
    That's my understanding. Center of gravity is an important thing. I can recall in my younger years in the martial arts. I was going to Hollywood to appear in action movies but life got in the way. In that context low CG makes you heavy and stable. It connects you to the earth. High CG is the opposite. As a pilot CG means everything. A plane rotates around three axis.CG changes with the distribution of weight within the aircraft. It's vital to calculate CG to insure it's within the envelope of the given aircraft.

    All that probably has nothing to do with bikes but underscores the importance of CG in virtually every aspect of our lives. I see where Graham and Geoff are going with all this. I'm thinking a slightly higher CG might give me more control with smaller/slower movements needed for corrections. This does seem the opposite of my current beliefs but I'll see how it goes. I suppose it's what you're used to.

    Thanks Geoff and Graham for posting such a thought provoking thread giving us commoners something to think about.

  50. #100
    mtbr member
    Reputation: smilinsteve's Avatar
    Join Date
    Jul 2009
    Posts
    8,613
    Quote Originally Posted by nemhed View Post
    In even more practical terms; in a side by side comparison between a Cleland and a recumbent in all riding conditions, which would be the better bicycle in most conditions? My money would be on the Cleland. Low CG is not the be all end all when it comes to two wheels vehicles. Whether a Cleland makes a better off-road bicycle than say a more "common" XC bike probably comes down to personal taste and riding styles, rather than the relative CG of the two bikes with their accompanying riders.
    I think the problem with recumbants is not the low center of gravity, but the ability of the rider to adjust COG while riding. Sitting in a chair is not an athletic position, and balance requires positional adjustment.

Page 2 of 6 FirstFirst 123456 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •