Page 1 of 4 1234 LastLast
Results 1 to 50 of 177

Thread: Fat Bike FAQ's

  1. #1
    mtbr member
    Reputation: bighit's Avatar
    Join Date
    Feb 2004
    Posts
    2,512

    Fat Bike FAQ's

    This thread is to address the most frequently asked questions fat bike riders get. I am no expert, but some here are and are welcome to add questions and answers.

    The first comment I get all the time is, what size are the tires.

    They are 26x3.7 inches wide and weigh about 1200 grams. they are made by a company called surly. http://www.surlybikes.com/
    You use a tube in them and run about 5-10psi depending on the terrain.

    There are some other tires available in the 26x3 inch size. they are Nokian and Arrow.
    They are more of a downhill tire than a snow tire. They are often used because they fit more frames and forks.
    These tires usually weigh about 1600 grams. Arrow still makes them and they are called the savage http://www.arrowracing.com/home.html
    The nokians will be hard to find, because they dont make them in the 3in size anymore.
    Last edited by rockcrusher; 03-10-2009 at 06:24 PM.

  2. #2
    All Lefty's, all the time Moderator
    Reputation: MendonCycleSmith's Avatar
    Join Date
    Feb 2005
    Posts
    15,024
    Tires, does Nokian still do them? The Arrows are 15lb for the pair (seriously), so bring your quads for those!

    Tire pressure?
    They run really low, like, 5 PSI low. More than 30 and they get scary

    "What's the bike for???"
    Sand, snow, anything else you feel like riding, and making you smile from the first pedal stroke

    "Are those motorcycle tires?"
    No.

    "Is everything special for them?"
    Frame, fork, bottom bracket, tires tubes, and the need for two rear, specific rimmed Pug wheels.

    All I can think of at the moment, sure others will percolate up through the fog...
    This is a Pugs not some carbon wannabee pretzel wagon!!

    - FrostyStruthers



    www.mendoncyclesmith.com

  3. #3
    FatBike Fiend
    Reputation: Wildfire's Avatar
    Join Date
    Feb 2004
    Posts
    958

    Soft condition riding

    I get this one a lot:

    "I want to ride on really loose sand and snow, how do they work?"

    Despite their ability to take you places no other bike can go, Fat Bikes do have their limitations. Even with the 3.7" tires and 65, 80, and now 100mm rims, you will probably find that they can bog down in really loose conditions like unconsolidated beach and dune sand, powder and loose granular snow, shale, and pea gravel.

    Often you will be able to ride downhill and maybe even on the level in these types of conditions but climbing won't work at all and steering can get very sketchy. You can decrease tire pressure to increase the footprint of the tires and increase flotation and performance but be aware that no tire can hold up to prolonged riding at very low air pressures and I've seen a lot of failed sidewalls and delaminated tire beads from doing just that.

    Oftentimes, it's possible to find an alternate line or route to hunt out those little pockets of firmer goodness and be able to ride without slowly destroying your tires. On beaches, the sand is firmer where it's still holding some moisture such as near the tide line. On snowmobile trails, the trail is loosest where the machine's track has rototilled the snow but it's often good riding if you can stay on the ski track, the proverbial "thin white line". A wonderful feature of snow is it's property of sintering, or packing down and becoming firmer after it's been disturbed so if you wait a little while after traffic, it usually gets firmer and much more ridable. Likewise, drifted snow can firm up into white slickrock dunes which make for incredible riding. If you're riding in a group, switching trail breaking duties will spread the burden out among your companions.

    An ironic thing, when I first started building FatBikes, I kind of intended them as a great equalizer for bigger, heavier riders because light people floated sooo much better on the SnowCat rims which were the current state of the art. And it worked great for a while but then smaller people started getting their hands on FatBikes and now guess what, we're right back to square one. In retrospect, I should have lobbied hard to enact laws to prevent this travesty. So yeah, being lighter is often a big advantage but then there are times that being heavier helps keep you from wallowing around as much as the lighter folks.

    Being able to adapt to challenging conditions is an innate part of the sport (can I call it a sport?) of Fat Biking. As you gain experience, you'll get much better at putting together micro lines to come up with a ridable route through seemingly impossible conditions and become adept at subtle weight shifts from front to rear to avoid bogging down.

    When worse comes to worse, just strap a wheel to each foot, and voila, snowshoes.
    Last edited by Wildfire; 03-11-2009 at 09:29 AM.

  4. #4
    FatBike Fiend
    Reputation: Wildfire's Avatar
    Join Date
    Feb 2004
    Posts
    958

    All time most asked Fat Bike question:

    "How come you don't put studs on those big tires for winter riding?"

    Contrary to popular opinion, most snow trails have pretty good traction because the big tires put a lot of surface area in contact with the snow. And even a lot of ice has decent traction, especially if it's flat and smooth, below freezing out, and/or there's a little windblown dust on it. You just have to ride smoothly over the ice stretches and not try any abrubt maneuvers.

    Most winter XC riding, at least around here in Alaska, is mostly on packed snow with short stretches of overflow or wind scoured ice. Adding studs increases rolling resisance drastically, so most riders opt to not use the studs and just be careful when crossing the occasional ice patches.

    There are times, though, when studded tires are life savers: rough, uneven ice, commuting, very slick ice with water on top of it, etc. I've had really good success using the 26 X 2.25" Nokian Fredie's Revenz tires on Large Marge rims. They are slow and sound like a freight train when you're riding, but traction is great, and they're big enough to offer good rim protection when hitting rocks or logs. Or if you have a spare set of 29er wheels for your Fat Bike, Nokian now has a decent 29er studded tire on the market. There's nothing like bombing down frozen class IV whitewater rivers or highmarking on icebergs which would be almost suicidal without studded tires. Just be careful, even studded tires have their limits.

    Here's some photos from the Knik Glacier. Everyone had FatBikes with studded tires.
    Attached Images Attached Images
    Owner, Trailwerx Trails Contracting
    Palmer, Alaska
    www.trailwerx.com

  5. #5
    'Calm Down'
    Reputation: GrumpyOne's Avatar
    Join Date
    Jan 2004
    Posts
    840
    Per bighit's request...

    Fat Fork info:
    • The Pugsley 100mm hub fork is 447mm AtoC.
    • The Jones 135mm hub fork is 435mm AtoC with 55mm of rake. (Not good for suspension corrected 29er retrofits.)
    • The Vicious Snow fork is 450mm and they can't/won't do longer do to blade availability. (I talked to Carl at NAHBS about it.)
    • DeSalvo makes his snow fork at 460mm. Which is the longest "production" fork I could find. He also is limited by available blade length due to the Uni-Crown construction.
    • If you need a longer fork for a 29er retrofit, I think Walt can make custom lengths using his segmented fork construction. But of course it's custom ($'s) and he has a back log.

    There may be other builders who can make "Fat" forks. But these are the ones I've looked into and have done Fat forks before.

    jw
    -

    "And single-speeding 29ers are mountain biking's equivalent of Scientologists..." - Captain Dondo

  6. #6
    FatBike Fiend
    Reputation: Wildfire's Avatar
    Join Date
    Feb 2004
    Posts
    958

    Addendum

    Quote Originally Posted by GrumpyOne
    Per bighit's request...

    Fat Fork info:
    • The Pugsley 100mm hub fork is 447mm AtoC.
    • The Jones 135mm hub fork is 435mm AtoC with 55mm of rake. (Not good for suspension corrected 29er retrofits.)
    • The Vicious Snow fork is 450mm and they can't/won't do longer do to blade availability. (I talked to Carl at NAHBS about it.)
    • DeSalvo makes his snow fork at 460mm. Which is the longest "production" fork I could find. He also is limited by available blade length due to the Uni-Crown construction.
    • If you need a longer fork for a 29er retrofit, I think Walt can make custom lengths using his segmented fork construction. But of course it's custom ($'s) and he has a back log.

    There may be other builders who can make "Fat" forks. But these are the ones I've looked into and have done Fat forks before.

    jw
    The Wildfire FatFork is 465mm A - C without having to use a blade stretcher.
    Owner, Trailwerx Trails Contracting
    Palmer, Alaska
    www.trailwerx.com

  7. #7
    (not that fast)
    Reputation: fastale's Avatar
    Join Date
    Jul 2007
    Posts
    958
    I'll add a question that has been on my mind, why no competition for the Endomorph? Considering the amount of bikes being built up around this tire/platform, some other tire companies must be trying to develop something, right?

  8. #8
    FatBike Fiend
    Reputation: Wildfire's Avatar
    Join Date
    Feb 2004
    Posts
    958

    Rear triangle offset explained

    I'll try to tackle this one since somebody asked it on another thread:

    "What's the deal with the offset rear stays on some Fat Bikes?"

    Here's how the offset came about:

    -The tires and rims are much wider then a standard mountain bike. This required the use of a wider chainline so the chain wouldn't rub on the big tire and wear out the sidewall.

    -In order to get the wider chainline, it was necessarry to build the frame with a wider bottom bracket shell for use with a wider bottom bracket spindle. At the time, most MTBs used a 68 or 73 mm shell with a 113mm spindle. That wasn't wide enough to clear the tire so we had to use wider bottom brackets. After a couple generations to accomodate increasingly wider rims and tires, we ended up with a 100 mm shell and a 145 mm bottom bracket spindle. So that solved that problem but led to:

    -Okay, the front problem was solved but led to a dilemna on the other end of the drive train: how to carry the new wider chainline back to the rear hub? At the time, there were very few wider then normal hubs available so we had to figure out a way to move the cassette out further from the bike's centerline to match the wider front chainrings using the available 135mm wide hubs. We decided to create a "virtual wide hub" by offsetting the rear triangle 18 mm out toward the drive side which brought the cassette out in line with the front chainrings. So that problem was solved but led to:

    -Now that we offset the rear stays, how do we bring the rim and tire back in line with the bike's centerline? If you were to take a standard rear mountain bike wheel and stick it in the dropouts, it would not line up with the centerline of the frame, it would be way out of line toward the drive side. That led to drilling offset spoke holes toward the drive side of the rear rim to bring the centerline of the rim and tire back into alignment with the frame's centerline. This allowed the use of equal length spokes on each side for a nice strong wheel build. Problem solved, or was it?

    -Somewhere along the line, the 29er market started taking off and I realized that the FatBike geometry was almost identical to the 29er geometry. Why not build a spare set of 29er wheels to make the FatBike a versatile, year-round machine? Unfortunately, the 29er rims are skinny and do not allow much of an offset spoke drilling. I had fairly good luck using a Bontrager offset rim, but the offset spoke drilling was only a couple mms so in order to make everything line up, I had to use much shorter (3 mm) spokes on the non-drive side of the rear wheel to get everything to line up. Not ideal: the spoke tension was very tight on the nondrive side and very loose on the drive side. Some hubs had wider flange spacing and I was able to get them to work. I've been riding the same rear wheel for years with no problems, but again, it's not ideal. Which led to:

    -Ditching the rear offset and using wider hubs which have recently come on the market. With a 160 mm hub everything works out nicely for chainline. Yes, they are a little heavier though the Chris King is lighter then many top 135mm hubs. And for sure, they are more expensive then most 135mm hubs but look at it this way: it allows your FatBike to be used rear round so think of how much money you'll save by not having to have two different bikes. That's why I've kept the 465mm axle to crown length on the rigid fork allowing a summer swapout to a 29er suspension fork. Losing the rear offset has the added benefit of making the framebuilder's job a lot easier: much less chainstay and seatstay bending. And of course, summer 29er wheels build up nice and strong.

    So anyway, if all of the above didn't give you a massive headache to try to comprehend, that is the deal with the rear offset stays.
    Owner, Trailwerx Trails Contracting
    Palmer, Alaska
    www.trailwerx.com

  9. #9
    hellraiser
    Reputation: coach#1's Avatar
    Join Date
    Mar 2006
    Posts
    74
    Thank you for the explanation - you cleared that up nicely.

    Love the look of your bikes BTW. The John Deer was my favorite.

    Coach
    eh?

  10. #10
    mtbr member
    Reputation: D.F.L.'s Avatar
    Join Date
    Jan 2004
    Posts
    1,839
    What about adding images of all available snow rims with Pugsley and Arrow tires mounted on each? I think people would benefit from seeing what sort of tire profile they'll get before purchasing.

    I'm crushed about no more Gazz 3.0s. I needed those.

  11. #11
    FatBike Fiend
    Reputation: Wildfire's Avatar
    Join Date
    Feb 2004
    Posts
    958

    Rolling Resistance Q

    If I had a dollar for every time I heard this one...

    "With all that rotating weight, aren't fat bikes hard to pedal?"

    I think this has been my biggest hurdle to get people to buy FatBikes. I encountered a ton of skepticism and naysayers when the FatBikes came out and a lot of those were very experienced winter cyclists. Even with people now routinely winning just about every winter race out there with various brands of fat bikes, I still encounter this a lot.

    While it's doubtful that you will see Lance riding one in the Tour de France the things roll pretty darn good on softer surfaces. And surprisingly well on hard surfaces too (but I still swap out with 29er wheels in the summer).

    First of all, the Endomorph tread is just a bigger version of a semi-slick. Back in the Nokian Gazzaloddi/Remolino 80 mm rim days, we used to spend a lot of time shaving knobs off our treads to get them to roll faster. No need for that with the Endo.

    Second, rolling resistance of a bike goes up drastically when the tires are making ruts in soft stuff because the wheels are always trying to climb up out of their own tracks. The big tires make a lot shallower rut so rolling resistance is a lot less on fat tires then skinny tires. Also the big wheels track better with a lot less wallowing around in soft conditions which saves a lot of wasted energy.

    There are probably other theories out there why they roll so well so techy types, feel free to chime in if you have one.

    So roll on, fat bikes, roll on.
    Owner, Trailwerx Trails Contracting
    Palmer, Alaska
    www.trailwerx.com

  12. #12
    (not that fast)
    Reputation: fastale's Avatar
    Join Date
    Jul 2007
    Posts
    958
    Quote Originally Posted by fastale
    I'll add a question that has been on my mind, why no competition for the Endomorph? Considering the amount of bikes being built up around this tire/platform, some other tire companies must be trying to develop something, right?
    I'm going to bump my question because I think it's a good one.

  13. #13
    mtbr member
    Reputation: bighit's Avatar
    Join Date
    Feb 2004
    Posts
    2,512
    Quote Originally Posted by fastale
    I'm going to bump my question because I think it's a good one.
    i wish there were more options. i think its because there is a small market right now.

  14. #14
    FatBike Fiend
    Reputation: Wildfire's Avatar
    Join Date
    Feb 2004
    Posts
    958
    Quote Originally Posted by bighit
    i wish there were more options. i think its because there is a small market right now.
    I'm hoping there will be some more options. I've heard a couple rumors but so far nothing else comparable has appeared on the market. It's probably just a matter of time until other manufacturers respond to the growing market.
    Owner, Trailwerx Trails Contracting
    Palmer, Alaska
    www.trailwerx.com

  15. #15
    mtbr member
    Reputation: bighit's Avatar
    Join Date
    Feb 2004
    Posts
    2,512

    100mm bottom brackets

    the pugsley takes a 100mm bottom bracket. the only ones i know of are,
    FSA Platinum DH isis
    Truvativ Gigapipe DH isis

    the next question is, can you use any of the new external bottom brackets and cranks. they all list the bb shell as 68/73.

    you would need a longer axle on the cranks right?

  16. #16
    mtbr member
    Reputation:
    Join Date
    Jan 2008
    Posts
    564
    Quote Originally Posted by Wildfire

    First of all, the Endomorph tread is just a bigger version of a semi-slick. Back in the Nokian Gazzaloddi/Remolino 80 mm rim days, we used to spend a lot of time shaving knobs off our treads to get them to roll faster. No need for that with the Endo.

    Second, rolling resistance of a bike goes up drastically when the tires are making ruts in soft stuff because the wheels are always trying to climb up out of their own tracks. The big tires make a lot shallower rut so rolling resistance is a lot less on fat tires then skinny tires. Also the big wheels track better with a lot less wallowing around in soft conditions which saves a lot of wasted energy.

    There are probably other theories out there why they roll so well so techy types, feel free to chime in if you have one.

    So roll on, fat bikes, roll on.
    A few years ago in Germany (where else...) some major bike mags decided to get to the bottom of rolling resistance once and for all. They kitted out several bikes with more wires than a spiderweb and went for it. I'm not going to translate all those articles (it's not my mother tongue for starters) and computer read-outs, but here's the gist:

    - it's not because it's got big, fat knobs that it rolls slower. Actually, some pretty agressive treads outperformed all semislicks on the market. Construction of the carcass is crucial to rolling resistance.

    - adding a tube increases rolling resistance x-fold. Friction between the tube and tire is responsible for that. Tubeless is the way to go.

    - the lower the tire pressure/wider the tire, the less rolling resistance on uneven terrain. Two reasons for that.
    First: a skinny, hard inflated tire presents a long, narrow footprint. A fat, underinflated tire presents a short, wide footprint. The latter has the least rolling resistance (don't ask me why, it's physics).
    Second: every pebble wants to stop a tire. A hard tire bounces over it, resulting in an upward movement and deceleration. A soft tire deforms and rolls over it without vertical movement, which results in less rolling resistance.

    - a heavier wheel takes more watt to accelerate, but once going pays dividends when the going gets rough. I forgot and am too lame to go look for the actual figures but I think it took like 5 extra watts to accelerate a heavy wheel vs a light one to 15 mph.
    But it took 20 watts extra per 200 yards to maintain that light wheel at that speed over rough stuff vs the heavier one.

    That pretty much sums up what we've all felt: a soft, fat tire is a drag on pavement but seems to accelerate when the going gets rough.
    Vs a skinny tire at mega psi: great when smooth, but hits a wall when hitting rough spots.

    And explains why our very fat tired bikes are faster on rough terrain than they appear at first sight.

    Another reason why fat bikes are so good on rough stuff is the rotational force. If you want to experience it, grab a spinning wheel by both hub ends and try to turn it. It's difficult and it's a main reason why we stay upright on a two-wheeled contraption.
    A heavy wheel generates more force than a light one and very much wants to keep in the same plane when spinning. Slippery roots or rock gardens don't impress heavy wheels as much as lighter ones.

    So don't follow skinny tired folk on their terrain... try to lure them onto yours

  17. #17
    All Lefty's, all the time Moderator
    Reputation: MendonCycleSmith's Avatar
    Join Date
    Feb 2005
    Posts
    15,024
    Quote Originally Posted by bighit
    the pugsley takes a 100mm bottom bracket. the only ones i know of are,
    FSA Platinum DH isis
    Truvativ Gigapipe DH isis

    the next question is, can you use any of the new external bottom brackets and cranks. they all list the bb shell as 68/73.

    you would need a longer axle on the cranks right?
    It's beyond just ISIS at this point. I just ordered a Race Face Atlas FR with a 100 mm spindle for mine. How could I not? It's available in purple now....

    The Surly Mr. Whirly is available in a 100mm option too. So yep, the external bearing BB's are a workable option too.
    This is a Pugs not some carbon wannabee pretzel wagon!!

    - FrostyStruthers



    www.mendoncyclesmith.com

  18. #18
    mtbr member
    Reputation:
    Join Date
    Aug 2007
    Posts
    739
    Phil Wood 100mm BB too, square taper

  19. #19
    FatBike Fiend
    Reputation: Wildfire's Avatar
    Join Date
    Feb 2004
    Posts
    958

    What he said.

    Great explanation which runs contrary to a lot of conventional wisdom.

    "
    Quote Originally Posted by caminoloco
    A few years ago in Germany (where else...) some major bike mags decided to get to the bottom of rolling resistance once and for all. They kitted out several bikes with more wires than a spiderweb and went for it. I'm not going to translate all those articles (it's not my mother tongue for starters) and computer read-outs, but here's the gist:

    - it's not because it's got big, fat knobs that it rolls slower. Actually, some pretty agressive treads outperformed all semislicks on the market. Construction of the carcass is crucial to rolling resistance."

    Not quite convinced on this point, shaving all the knobs except the outer row on the old Nokian Gazzaloddi 3.0 tires made them noticeably faster. I agree that supple sidewalls make tires faster on soft and uneven surfaces.

    "- adding a tube increases rolling resistance x-fold. Friction between the tube and tire is responsible for that. Tubeless is the way to go."

    So far all the attempts I've heard about to make a winter tubeless setup for the big tires and rims at low air pressures in the cold have failed. If somebody could figure that one out it would be a big breakthrough.

    "- the lower the tire pressure/wider the tire, the less rolling resistance on uneven terrain. Two reasons for that.
    First: a skinny, hard inflated tire presents a long, narrow footprint. A fat, underinflated tire presents a short, wide footprint. The latter has the least rolling resistance (don't ask me why, it's physics)."

    I think it has to do with how far the tire is sinking into the snow. Short and wide could be compared to a rolling pin on dough, long and skinny is more like a pizza cutter.

    "Second: every pebble wants to stop a tire. A hard tire bounces over it, resulting in an upward movement and deceleration. A soft tire deforms and rolls over it without vertical movement, which results in less rolling resistance".

    Amen.

    "- a heavier wheel takes more watt to accelerate, but once going pays dividends when the going gets rough. I forgot and am too lame to go look for the actual figures but I think it took like 5 extra watts to accelerate a heavy wheel vs a light one to 15 mph.
    But it took 20 watts extra per 200 yards to maintain that light wheel at that speed over rough stuff vs the heavier one."

    That's interesting.

    "That pretty much sums up what we've all felt: a soft, fat tire is a drag on pavement but seems to accelerate when the going gets rough.
    Vs a skinny tire at mega psi: great when smooth, but hits a wall when hitting rough spots.

    And explains why our very fat tired bikes are faster on rough terrain than they appear at first sight.

    Another reason why fat bikes are so good on rough stuff is the rotational force. If you want to experience it, grab a spinning wheel by both hub ends and try to turn it. It's difficult and it's a main reason why we stay upright on a two-wheeled contraption.
    A heavy wheel generates more force than a light one and very much wants to keep in the same plane when spinning. Slippery roots or rock gardens don't impress heavy wheels as much as lighter ones.

    So don't follow skinny tired folk on their terrain... try to lure them onto yours
    "

    Thanks.
    Owner, Trailwerx Trails Contracting
    Palmer, Alaska
    www.trailwerx.com

  20. #20
    mtbr member
    Reputation:
    Join Date
    Jan 2006
    Posts
    415

    Where?

    [QUOTE=MendonCycleSmith]It's beyond just ISIS at this point. I just ordered a Race Face Atlas FR with a 100 mm spindle for mine. How could I not? It's available in purple now....

    Where does one order the 100mm Atlas? thx.

  21. #21
    All Lefty's, all the time Moderator
    Reputation: MendonCycleSmith's Avatar
    Join Date
    Feb 2005
    Posts
    15,024
    Quote Originally Posted by Stroganof
    Where does one order the 100mm Atlas? thx.
    I'm pretty sure Quality Bicycle Products has them, I got mine direct from RF, through an industry only offer.

    I know they will sell to your local shop too.

    Shouldn't be too hard, easy enough to order, but I doubt too many store will have one sitting about on a shelf, correct me if I'm wrong....
    This is a Pugs not some carbon wannabee pretzel wagon!!

    - FrostyStruthers



    www.mendoncyclesmith.com

  22. #22
    No, that's not phonetic
    Reputation: tscheezy's Avatar
    Join Date
    Dec 2003
    Posts
    14,363
    Frame tire clearance information for two different Surly Pugsleys:

    With an Endomorph mounted on a Large Marge rim, I put a little piece of tape on the chainstays and seatstays at the point where the tire side of the tire comes closest to the stays, then removed the wheel and measured the inside-to-inside distance between the stays at the point where the tire passes. On the Pugs, the widest point on the chainstays is well forward of where the tire passes for some reason.

    Here is an example of where I determined I would measure the Pugs. The little black double arrow indicates the closes point between the tire and chainstay and this is where I stuck the piece of tape:



    First, on a size small Pugs, I marked the spot with tape and I then pulled the wheel and measured just shy of 113 mm inside to inside on the chainstays:



    The seatstays were 115 mm:



    On a size medium older Pugs (purple), I got the following numbers (which were within 1mm of the other Pugs).

    Chainstays 112mm where the tire passes:



    Seatstay 116mm:



    For comparison's sake:
    Quote Originally Posted by pbasinger
    Yesterday I had the opportunity to measure a larger sized [aluminum] 907 in the method described by tscheesy an got 111 mm top and bottom.
    Quote Originally Posted by bflemin
    Here are measurements we made of the chain stay/seat stay widths on the 9:ZERO:7 ti and aluminum models. For the aluminum 907, we measured widths of 111mm at the seat stays and 110 mm at the chain stays. On the titanium 907, we measured 125 mm at the seat stays, and 121 mm at the chain stay.
    Quote Originally Posted by Wildfire
    Tire clearance [on the 2010 Wildfire FatBike chromoly frames] at 320 mm radius (point of maximum width of tire) from the axle is 111 mm on the chain stays and 116 mm at the seat stays.
    And finally some Surly Endomorph 3.7 effective tire width numbers originally posted by pbasinger. The Endomorphs were mounted on the rims listed below and inflated to 10psi:

    • Speedway 70mm rim with Endomorph: 94.5 - 95.5 mm
    • Vicious Cycles 80 rim with Endomorph: 95.5 - 96.5 mm
    • 100mm rim with Endomorph: 106.5 - 107.5 mm
    Last edited by tscheezy; 11-11-2009 at 12:29 AM.
    My video techniques can be found in this thread.

  23. #23
    mtbr member
    Reputation: wheelbender6's Avatar
    Join Date
    Sep 2007
    Posts
    307
    Does a 24"X3" qualify as a Fat Bike? Some Felt cruisers are sold with 24X3.
    Seems that fitting a 24X3 to an MTB frame designed for 26X2 would be simple.
    "I don't suffer from insanity!I rather enjoy it."

  24. #24
    bored ex-shop rat
    Reputation: velopax's Avatar
    Join Date
    Jun 2007
    Posts
    375

    Caution;  Merge;  Workers Ahead! 100mm BB/crank options

    That's a short list of the 100mm BB & cranks options:

    Phil Wood square JIS BB with some square cranks










    FSA Platinum Pro DH or Truvative GigaPipe Team DH ISIS BB with some ISIS cranks









    Race Face Atlas FR & Diabolus DH cranks/BB sets





    Profile Racing BMX cranks/BB set





    Truvativ Howitzer Team BB with some Truvativ cranks with Howitzer interface








    Surly Mr.Whirly cranks with some external bearing BB




    The Hive 15G cranks/BB set





    It's maybe helpfull
    Last edited by velopax; 01-06-2010 at 02:46 AM.
    Life is like a ten speed bicycle. Most of us have gears we never use. Charles M. Schulz (1922 - 2000)

  25. #25
    mtbr member
    Reputation:
    Join Date
    Aug 2007
    Posts
    20
    Quote Originally Posted by wheelbender6
    Does a 24"X3" qualify as a Fat Bike? Some Felt cruisers are sold with 24X3.
    Seems that fitting a 24X3 to an MTB frame designed for 26X2 would be simple.
    I think this was the point that Surly was trying to make with the Rat Ride 1x1=11 Anniversary bike. It's got slick Hoggy g 24x3.5 tires as stock equipment on 24 inch Large Marge rims.

  26. #26
    mtbr member
    Reputation:
    Join Date
    Mar 2007
    Posts
    73
    Yep. Either that or a 1X1 built up as a Mini Pugs could be called a Poor Man's Fat Bike. There is no need to get a specialized Fat Bike when you can do the same thing with a generic MTB that will also allow you to run conventional MTB tires most of the year.

  27. #27
    mtbr member
    Reputation:
    Join Date
    Aug 2008
    Posts
    1,900
    I've spent lots of time on Snowcat rims with 2.5 inch Diesel Pro's on a regular mountain bike and there is no comparison to a real Fatbike. If you can find a fatbike in your budget you will not regret it.

  28. #28
    mtbr member
    Reputation:
    Join Date
    Mar 2007
    Posts
    73
    I'd maintain a Fat Bike built up with more affordable components is a real Fat Bike. Until you've tried a 1X1 Fat Bike, don't knock it.

  29. #29
    mtbr member
    Reputation:
    Join Date
    Aug 2008
    Posts
    2,500
    fyi: niner carbon fork (the 550 gram one) fits a 3" gazzi on a sun s-type rim.
    don't have an endo but doubt it'd work, but for half-fat folks... there you go, lightest fatty fork around.

    edit: oh! just notice the profiles up there, reminded me; i had top grab aftermarket cups for my profiles, decided to try them without the spacers, lspaced the cups furthest out (to simulate wide bb)- they measured out a smidge over 90mm wide.
    I think with those lower profile cups and the arms a couple mm out from fully pressed on you would get the bb cups spaced out for 100mm easily.
    If steel is real then aluminium is supercallafragiliniun!

  30. #30
    mtbr member
    Reputation:
    Join Date
    Aug 2008
    Posts
    2,500
    Quote Originally Posted by byknuts
    fyi: niner carbon fork (the 550 gram one) fits a 3" gazzi on a sun s-type rim.
    don't have an endo but doubt it'd work, but for half-fat folks... there you go, lightest fatty fork around.

    edit: oh! just notice the profiles up there, reminded me; i had top grab aftermarket cups for my profiles, decided to try them without the spacers, lspaced the cups furthest out (to simulate wide bb)- they measured out a smidge over 90mm wide.
    I think with those lower profile cups and the arms a couple mm out from fully pressed on you would get the bb cups spaced out for 100mm easily.

    edit numero dos: shaved the side knobs down on the gazzi, fits in a fox talas fork now.
    mud clearance is on the short side, but the notion of 3" of tire under 5" of fork was too intriguing for me not to try it. it's an older talas too, not the nifty new 140mm guys, they might be even easier to work with.

    scratch the previous: it WILL work, but you have to shave the center knobs down to a very minimal height. (think endomorph tread depth) which quite frankly for a front tire makes no sense.
    so as much fun to look at as it may be it's not REALLY going to work for anything but beach duty.
    fits just fine in a fox 36 though.
    Last edited by byknuts; 08-08-2010 at 11:32 AM.
    If steel is real then aluminium is supercallafragiliniun!

  31. #31
    mtbr member
    Reputation: jddjirikian's Avatar
    Join Date
    Aug 2006
    Posts
    444
    What about recommended tire pressures?

    Snow v. Sand v. Hardpack?

    I suspect the snow answer will depend on the type of snow (fluffy, wet, heavy, etc.)?

    Thanks

  32. #32
    Woodybearsinglespeed
    Reputation:
    Join Date
    Apr 2009
    Posts
    1

    New question here. frame offset

    hi,

    might be asking an old question, but here goes

    if running single speed/hub gear and fat tire could you work something with an 83mm BB and a non offset rear triangle

    only asking as my surly 1x1 got damage by a car and needs rear triangle repairing, and the car driver insurance is paying for the repair (tried for a new frame but not having it )

    thanks for your help


  33. #33
    30-ton War Machine
    Reputation: edgerat's Avatar
    Join Date
    Oct 2008
    Posts
    794
    Gyroscopic effect of all that mass? We don't have much snow here in WA but, I would like to toy around with a Pugs.
    Isaac

  34. #34
    mtbr member
    Reputation:
    Join Date
    Jul 2007
    Posts
    1,043

    Salsa Enabler Fork questions

    Q: What is the required hub/brake setup on the Enabler?
    A: The Enabler is designed to use a standard 135 mm spaced, 10 mm axle rear hub (cassette, single speed, ect) and a standard front IS mount disc brake*.

    Q: Can I use a 135 mm spaced FRONT hub (Paul, Fatback/Hadley) in an Enabler fork?
    A: No. The brake rotor will be too close to the IS disc tab, and the 9 mm axle ends will be too loose in the Enabler's 10 mm dropout slots. Modifications could be made to make it work, however.


    *A word on IS mount dimensions.
    For the most part, most "front" and "rear" brake calipers are identical. Front and rear caliper adapters, however, are different dimensions, because the IS radial dimensions are different front to rear.
    The IS axial dimensions (distance from IS mounting tab to the rotor mounting surface of hub) are the same front to rear. However, the IS dimensions from the axle end/dropout surface (not the IS tab) to the rotor mounting surface of the hub is 10 mm in the front and 15 mm in the rear. This is why a 135 mm spaced front hub won't work in an Enabler; the brake rotor will be 5mm too close to the fork's IS tab.

  35. #35
    mtbr member
    Reputation:
    Join Date
    Jul 2007
    Posts
    1,043

    Surly Pugsley forks

    Surly offers the Pugsley fork in three variations: Symmetrical with 100 mm axle spacing, symmetrical with 135 mm axle spacing, and offset with 135 mm axle spacing (the original Pugsley fork).

    The 100 mm non-offset fork uses a standard 100 mm front hub, and requires a front brake caliper adapter.

    The 135 mm non-offset fork uses a standard 135 mm REAR hub, and requires a front brake caliper adapter. This is the same setup as the Salsa Enabler fork.

    The 135 mm offset fork uses a 135 mm REAR hub, and requires a REAR brake caliper adapter.

    Trying to use a 135 mm front hub (Paul, Speedway, ect.) in either of the 135 mm spaced forks will encounter the same problems as mentioned in the above post on the Enabler fork (brake rotor spacing and axle diameter).
    Last edited by Andy FitzGibbon; 07-06-2011 at 05:40 PM.

  36. #36
    mtbr member
    Reputation:
    Join Date
    Jul 2007
    Posts
    1,043

    135 mm front hubs

    The Paul WHUB and the various offerings from Fatback (Hadley and import) are all true 135 mm FRONT hubs. They have 9 mm axle ends and front disc rotor spacing, just like a standard 100 mm front disc hub. These hubs will work in Fatback forks and the 907/White Bros SnowPack fork. They won't work in the Salsa Enabler or either of the 135 mm Pugsley forks without modifications.

    Surly's New Disc 135 mm front hub is actually just a rear hub without freewheel threads. So, it has 10 mm axle ends and rear disc rotor spacing. This hub will work in the Salsa Enabler or either of the 135 mm Pugsley forks, but won't work in any of the Fatback forks or the 907/White Bros. Snowpack fork without modification.

  37. #37
    mtbr member
    Reputation: ironbirdexplorer's Avatar
    Join Date
    Sep 2008
    Posts
    7
    I just bought a SALSA MUKLUK two months ago. I put it together with a bike mechanic-friend of mine and hit the trails. The terrain here in southwestern Manitoba is relatively flat (Canadian prairie) and sandy. I was out on the sandy trails about a month ago, and experienced some chain suck in the wet sand. I've had chain suck before, but this time seemed much worse. I was able to keep going, but I noticed things just didn't "feel right". When I got home, I examined my drive train and noticed my middle chain ring was bent in a couple of different places and there were slivers of metal poking out from the sides of the teeth in the chain ring where the chain had sheared into the metal of the chain ring.

    My mechanic friend hasn't seen it yet, but he says that we might be able to file the slivers off between the teeth and try to straighten out the chain ring.

    Has anybody else experienced this before? I don't think it's just because it's a fat-tire bike, but I haven't had it that bad on my other bikes.

    Should I stock spare middle chain rings? Should I keep separate drive trains for winter and summer?


    Steve
    (ironbirdexplorer)

  38. #38
    mtbr member
    Reputation:
    Join Date
    Jun 2009
    Posts
    83
    I'm planning to build "fatbike" based on the Troll frame and 26x3.0 tires ( duro leopard or gazzaloddis ), for autumn-winter-spring riding ( and to swap wheels to 700c for summer commuting ). So I decided to ask here. Not going for true fatbike, because I just dont have a place for three bikes ( now paragon 29er + commuter rigid, which frameset will be changed to Troll )

    How critical is rim width ? Is it absolutely necessary to use widest rim possible ( large marge, 65mm ) ?
    Or it will be almost identical with 47mm trial rims ? It is a matter of money, i can get 47mm rims almost 4 times cheaper , than 65mm marges...

    Will I be able to use non offset large marge rims on standart slx hubs wheels ( front 100mm and rear 135mm ) on true fatbike frameset ?

  39. #39
    mtbr member
    Reputation:
    Join Date
    Apr 2008
    Posts
    2,054

    Tire Weights and Widths

    Surly Big Fat Larry 26x4.7
    Weighs: 1433gr (120tpi)
    Measures:
    65mm Rim-98mm-100mm
    80mm Rim-104mm
    100mm Rim-113-118mm

    Surly Larry 26x3.8
    Weighs: 1530gr (27tpi) 1400gr (120tpi)
    Measures:
    65mm Rim-92mm
    80mm Rim-96mm
    100mm Rim-105mm

    Surly Endomorph 26x3.7
    Weighs:
    Measures:
    65mm Rim-92mm
    80mm Rim-
    100mm Rim-

    Surly Nate 26x3.8
    Weighs: 1637gr (27tpi) 1530gr (120tpi)
    Measures:
    65mm Rim-96-98mm
    80mm Rim-
    100mm Rim-

    Surly Black Floyd 26x3.8
    Weighs: 1237gr (27tpi)
    Measures:
    65mm Rim-
    80mm Rim-
    100mm Rim-

    Rims:

    Surly Large Marge 65mm
    Weighs 1150g (DH), 950g (XC)

    Surly Rolling Darryl 82mm
    Weighs 1030g (solid) 850g (drilled)

    Flattop 100mm
    Weighs 1150g (solid), 950g (drilled)

    Flattop 80mm
    Weighs 980g (solid), 795g (drilled)

    Vicious Cycles Graceful Fat Sheba 80mm
    Weighs 1310g

    Credits: benwitt11, FTMN, mikesee, Andy FitzGibbon, wadester

    I'm trying to complete this table, so if you have a missing piece please PM me. Thanks!
    Last edited by JAGI410; 09-13-2011 at 08:33 PM.
    Jason
    Disclaimer: www.paramountsports.net

  40. #40
    Vagician
    Reputation: EPcycles's Avatar
    Join Date
    Dec 2009
    Posts
    295
    Great job with the table. Exactly the information that I was looking for with the new and current tires. Thanks. Also, I currently am running my larry 3.8s tubeless on 47mm trial tech rims for summer. They both measure 88mm.
    Last edited by EPcycles; 08-28-2011 at 09:13 PM.

  41. #41
    mtbr member
    Reputation: jfkbike2's Avatar
    Join Date
    Feb 2005
    Posts
    1,012
    My weights are similar...

    BFL. 120 tpi 1420 gr
    Nate. 120 tpi 1520 gr
    Larry. ? 1480 gr

    Very interesting that the BFL is lighter than the skinny Larry.

  42. #42
    mtbr member
    Reputation: wieczorek24's Avatar
    Join Date
    Dec 2010
    Posts
    81
    On post #24 there is this information

    Speedway 70mm rim with Endomorph: 94.5 - 95.5 mm
    Vicious Cycles 80 rim with Endomorph: 95.5 - 96.5 mm
    100mm rim with Endomorph: 106.5 - 107.5 mm

    Found it when looking for endo widths

  43. #43
    mtbr member
    Reputation:
    Join Date
    Jul 2007
    Posts
    1,043
    Surly now offers two different Mr. Whirly spindle lengths for 100 mm bottom bracket shells:

    Pugsley: 157 mm
    Moonlander: 171 mm, includes spacers to take up additional space between crankarms and bottom bracket cups.

    The Moonlander spindle is longer so that the crankset's chainline will match up with the 28 mm rear offset. But, it could easily be used on other bikes to deal with crankarm or tire/chain clearance issues.

  44. #44
    mtbr member
    Reputation:
    Join Date
    Jul 2005
    Posts
    421

    tire weights, additional

    very slightly worn Endomorph 3.7, unknown tpi = 1330g

    Larry 3.8, 120 tpi = 1430g

    Larry 3.8, 27 tpi = 1500g

    weighed on Alpine hanging digital scale.

  45. #45
    mtbr member
    Reputation:
    Join Date
    Oct 2011
    Posts
    14

    Please, please read..

    Hello all,

    I am carrying out initial market research for my Final Year Project for my BEng Mechanical Engineering Degree at the University of Hull. I would be incredibly appreciative of any response and questions you may have. I am very new to the idea of FatBikes so please if I am stating incorrect information please correct me. My supervisor at the University of Hull has given me the following task:

    A new generation of off-road bike, so called 'FatBikes' utilise large (100mm wide) tyres running at relatively low pressures (5-20psi) to handle soft terrain like snow, mud and sand. Conventional portable bicycle pumps are designed to deliver low volumes of air at high pressure (60-120psi). Fatbike tyres are relatively easy to puncture and cyclists are faced with an onerous task to repair and re-inflate them when 'on the trail' due to their relatively large volumes. Additionally cyclists like to 'tune' the running pressure to the terrain, and therefore some means of measuring the absolute pressure accurately is required. The scope of the project is to design and evaluate a low-weight, highly portable, manufacturable solution to this issue. There is no preferred conceptual solution, the project should include a widely ranging survey of air-pumping technologies.

    Adding to this, im hoping to manufacture a prototype and then test it.

    Firstly can anybody suggest any pumps on the current market and/or send me a link to the relevant websites?

    Sounds obvious but do FatBike tyres have an inner tube and is the value on this inner tube the same as a conventional bike tyre?

    Many, many Thanks

    Dave

  46. #46
    mtbr member
    Reputation:
    Join Date
    Jun 2008
    Posts
    542
    [QUOTE=daveyboy150;8523581]Hello all,
    Firstly can anybody suggest any pumps on the current market and/or send me a link to the relevant websites?
    Any standard mechanical portable pump cycling will work. Look at Topeak, Blackburn, Lenzyne, Portland Design Works etc. Google them. Also, portable CO2 powered "insta-flate" style gas canisters can work too though big tires need multiple compressed gas tubes to get them up to adequate pressure.

    Sounds obvious but do FatBike tyres have an inner tube and is the value on this inner tube the same as a conventional bike tyre?
    Most fat tire bikes use butyl rubber inner tubes. They are larger in volume due to the larger tire size. They typically use either Presta ("French") or Shraeder ("automobile style") valves. Some enthusiasts have experimented with tubeless style setups similar to those used in conventional MTB tires, though the rims and tires available for fatbikes are not tubeless specific, meaning the tire casings are not sealed and the rims do not have double wall sealed construction and the tight beads as seen n conventional MTB tubeless systems. Some fat bike users will put tubeless tire sealant (Stan's No Tubes) in to the innertube to help seal the inner tube against small punctures from thorns if riding in sandy, desert type conditions.

  47. #47
    mtbr member
    Reputation:
    Join Date
    Oct 2011
    Posts
    14
    thank you very much for this information, I will be using this for my research.

    Dave

  48. #48
    mtbr member
    Reputation:
    Join Date
    Oct 2011
    Posts
    14
    Ps are there any websites that give clear details on the tyres / inner tubes so that I can reference this in my report?

    Many thanks

  49. #49
    mtbr member
    Reputation:
    Join Date
    Oct 2009
    Posts
    363
    regular MTB bike and 65mm rims,

    thinking it should fit, got a giant reign bike,
    and 2.5 tires fit.
    so what about some large marge 65mm wheelset ?
    and where to get 15QR front ?

    other than that, would like some studded tires,
    at least in the front. do have nokian, but they seam skinny ?
    any options ? or tools to do some kendas ?
    cheers, Rob

  50. #50
    mtbr member
    Reputation: Smallfurry's Avatar
    Join Date
    Jul 2009
    Posts
    413
    Could'nt quite decide wether this or the demo....sticky, was the correct thread for this. So I'v just gone for this one.

    Fork lengths for the various fat frames?
    There seems to be two main lengths. ~450mm ATC, and ~470mm ATC. But browsing the various stores/sites, its seems difficult to track down which frame is designed for which. I like the idea of a shorter front end, because I myself am short, so it aids fit. But the option to swap to a suspension fork, is a nice piece of versatility. Could people please fill in the gaps, and apols if this has been covered (I could'nt find it).

    Salsa Mukluk - ATC = 468mm
    Surly Pugsly - ATC = 447mm
    Surly Moonlander - ATC = 447mm
    Alu 9zero7 - ATC = ???mm
    Alu fatback - ATC = ???mm
    Sandman Gobi - ATC = ???mm
    On-one - ATC = ???mm

Page 1 of 4 1234 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
  •