26er with 650b front only

[bidaci]

I have a Giant AC1 that I usually run 2.35 to 2.5 26 inch tires. Do to an injury I swapped the normal size tires to a smaller 26x2 figuring I would lighten the bike up and enjoy non technical singletrack and fireroads more. What surprised me was over all the bike was so much responsive even in some of the tighter singletrack. What was a problem was I noticed the front tire getting stuck on rocks that I normally would have bounced right over. Got me thinking about a larger front tire and the smaller rear. The downside is the additional weight that I could do without.

Then I remembered the 650b! So now I have some questions. If I am reading the specs properly, according to the tire guru (shiggy's site), a 650b tire would be similar in overall diameter (344-354mm) to a larger, wider, heavier 26 inch tire (IRC Kujo DH 346mm).

Am I reading this correctly?

If this is the case, I should be able to get a 650b tire with the same diameter and almost half as heavy as the larger 26 tire. Now that leaves the rim as a variable. Are the 650b rims much heavier then the 26 counterpart?

I just about have myself convinced to try a 650b front and keep the skinny 26 rear. Can I get the benefits of a larger tire by going 650b as a big 26 tire without the downside of the weight?

No hucking, no drops

Yes/No? Thoughts?

Giant AC1
Rockshox Psylo

Had a IRC Kujp 2.35 at one point and a Maxxis Mobster 2.6 but they are to damn heavy.

[MMcG]

I say go for it - especially since your fork - the Psylo - has ample room for 650b!

[derby]

Compared to a 26 inch wheel, it may add about 100 grams, if that much, using the same width 650b tire, rim, and longer spokes.

Doing 650b front only raises the front of the frame 1/2 inch and steering becomes a bit more floppy, similar to using a much larger front tire for handling changes. It slacks the fork angle and slows turning - similar to the feel of raising the fork travel 1 inch using the same size wheels front and rear.

For front only 650b to maintain leg reach to maintain your familiar weight center over the pedals and wheels, lower your bars 1/2 inch and bump your seat forward about 1/2 inch and up slightly. The difference in turning feel and balance is then nearly eliminated and forgotten in a ride or two (except for the gains in rolling ease and traction).

[Davidcopperfield]

Originally Posted by bidaci

No hucking, no drops

Yes/No? Thoughts?

Giant AC1
Rockshox Psylo

Had a IRC Kujp 2.35 at one point and a Maxxis Mobster 2.6 but they are to damn heavy.

Yes I know small wheel do not work so well. Have you thought of makign it 69er? Just get a 100 or 120mm fork and 29" wheel and if you must get a 27,5" for the rear.

[bidaci]

Originally Posted by MMcG

I say go for it - especially since your fork - the Psylo - has ample room for 650b!

I wouldn't expect anything less from you. But what took so long for you to answer?

Originally Posted by derby

Compared to a 26 inch wheel, it may add about 100 grams, if that much, using the same width 650b tire, rim, and longer spokes.

Doing 650b front only raises the front of the frame 1/2 inch and steering becomes a bit more floppy, similar to using a much larger front tire for handling changes. It slacks the fork angle and slows turning - similar to the feel of raising the fork travel 1 inch using the same size wheels front and rear.

For front only 650b to maintain leg reach to maintain your familiar weight center over the pedals and wheels, lower your bars 1/2 inch and bump your seat forward about 1/2 inch and up slightly. The difference in turning feel and balance is then nearly eliminated and forgotten in a ride or two (except for the gains in rolling ease and traction).

I would like to compare the 2.1 650b to a Maxxis Mobster 2.6 or Kujo DH 2.3 in 26" diameter and weight. I would think the 650b would be lighter and nt much bigger?

My HA is already at 69.5 but luckily my Psylo is uturn so I can play with the height.

Originally Posted by Davidcopperfield

Yes I know small wheel do not work so well. Have you thought of makign it 69er? Just get a 100 or 120mm fork and 29" wheel and if you must get a 27,5" for the rear.

I found that the skinnier tires and the lack of weight a plus. I am only assuming it is the diameter that was making the difference when I stuffed the front into a small rock and stopped. 650b would be an easier swap and at some point I could try 650b on the rear as well.

All I need to do is find MMcG at one of the NEMBA rides and steal a rear wheel for a test fit.

[TNC]

bidaci, IMO this is the beauty and logic of 650B. One doesn't have to sacrifice travel or odd geometry to get a slightly taller wheel/tire combo. Personally I still like 26" on the rear, but I have been totally convinced on the performance benefit for the front to be 650B on both my Nomad and '08 Stumpjumper FSR. I rode both of these bikes for some time with a 26/26 setup, and there's no question in my mind that cornering and roll-over feedback is noticeably improved. I tried a couple of very good full suspension 69'ers and really like some of the characteristics, but in rough terrain the reduction in travel necessary to run that big wheel just wasn't quite enough for my riding style. The weight difference was surprisingly close between a 26" CrossMax XL front with a 730g front tire and the Blunt 650B/20mm Dimension hub/SS spokes with a 730g 2.3 NeoMoto...maybe 50g heavier. I love the ability to run a 160mm fork and the 650B on my Nomad. It's worth it.

[enFuego]

Putting a Neomoto on the front of my 2003 Santa Cruz Superlight was an improved bike, for me. It lead me to go for a 09 Heckler with 650B front and rear, which is working nicely for me. I'll try to attach some pics here of a side-to side comparison of a Neomoto next to a 2.5" Nevegal. For me, I liked the improved roll-over-ability of the Neomoto, but then again, I ride slow. I couldn't tell you which of the two tire set-ups has better super highspeed cornering grip, but I really like the qualities of the 650B better (one of which is better rear tire climbing traction). YMMV

[MMcG]

That second image is a very good image showing the size diff.

[umarth]

For my riding style, a 650b front and a 26" back is probably near perfect. I appreciated the slack angles.

[MMcG]

Originally Posted by bidaci

I wouldn't expect anything less from you. But what took so long for you to answer?



I
All I need to do is find MMcG at one of the NEMBA rides and steal a rear wheel for a test fit.

Hey - I've got a rear wheel that I can loan out or you can have for little $$ or trade for parts.

I bought it from BikesonSnow on the site here and it would make for a good tester wheel.

I'm waiting on a complete wheelset from Chad at Red Barn Bikes - so let me know if you want to work something out for the rear wheel. You can find my Spam Ad thread for it if you scroll down this forum a bit.

[bidaci]

I have been looking at the SpamAds on here to see what the expense would be. This is what happens when we have crappy weather and I get bored.

So on to butchering my own thread and I will try to keep it as coherent as possible.

I had IRC Kujo 26x2.35 on there. They measure (BY MTBTIRES.COM) at the tallest point 346mm and weigh 1083g.

The Quasimoto 650b x2.0 measure 344mm and weigh 555g.

I currently have some Michelin 26x2.0 at 338mm and 580g.

I love the way the bike feels with 1.5lbs taken off each in and the thinner wheels on some of the tighter rock gardens. I miss the extra diameter and volume of the bigger/wider tires though. This is what has me thinking of the 650b. A narrow 2" tires with the diameter of the 2.35 and not the weight penalty? Is this possible?

My 26" wheelset with the kujos would weigh ~2293g and with the 26x2 ~1790g. Does anyone have an idea as to what their front 650b wheel assembly weighs?

[keen]

What surprised me was over all the bike was so much responsive even in some of the tighter singletrack. What was a problem was I noticed the front tire getting stuck on rocks that I normally would have bounced right over.

Going to a smaller / shorter height tire will increase your steering response - going 650b will be two steps in the wrong direction. The added height of a 650b plus the change in "trail" is deffinitly noticable - adjusting the travel to compensate for the added wheel height doesn't correct the trail unless you drop the travel further. Build a light 26" wheel and run a hi volume tire w. shallow tread if you want response and roll over.

[reformed roadie]

Originally Posted by keen

What surprised me was over all the bike was so much responsive even in some of the tighter singletrack. What was a problem was I noticed the front tire getting stuck on rocks that I normally would have bounced right over.

Going to a smaller / shorter height tire will increase your steering response - going 650b will be two steps in the wrong direction. The added height of a 650b plus the change in "trail" is deffinitly noticable - adjusting the travel to compensate for the added wheel height doesn't correct the trail unless you drop the travel further. Build a light 26" wheel and run a hi volume tire w. shallow tread if you want response and roll over.

Huh?
Once I got my position sorted, I have no negatives from running a 650b w/ 26" rear on my blur. I think the most important point is what bike you start with and how steep it is upfront. For trail riding, my blur was too steep.

How much does a 2.5 Nevegal weigh? I am guessing quite a bit more than a 750gm Neo.
And it's radius is still significantly smaller. And unless you run a wide enough (read: heavy) rim, you are going to have the tire squirm and fold.
This is precisely why 650b makes sense.

keen - with all due respect, I don't get where you are coming from.

[keen]

keen - with all due respect, I don't get where you are coming from.

I think the most important point is what bike you start with and how steep it is upfront.


Exactly you don't know where I am coming from. If you do the math steering reposnse will not be the same - there is a change in front end height and fork trail . If you start w/ a steep HA the effects of a 650b may not be as noticable. The OP want faster steering which isn't going to be the case - he doesn't have a Blur.

[elrancho66]

Originally Posted by MMcG

I say go for it - especially since your fork - the Psylo - has ample room for 650b!

I say go for it also and see if it works for you. I have been running a Nevegal with a Velocity 650 B Blunt on the front of my Kona A Full Suspension SS rig and it's a blast,,,,,,,,26 out backright now but there is plenty of room for a 650B setup. My fork is a 26" Fox X100, plenty of room for the taller tire/rim combo. Steering is a bit slower but the front end rolls over stuff better and it still climbs decent

[bidaci]

Originally Posted by keen

The OP want faster steering which isn't going to be the case - he doesn't have a Blur.

I am actually looking to get the benefit of the larger diameter tire for rollover of obstacles that I had with the larger 26" tires. My thoughts where I could get some of that back with the 650b without the extra weight of fat tires (as well as some more air volume for lower pressure). I may have not been clear on the original post but I cannot see where I wanted faster steering. That I could get by cranking the uturn down from 120mm to 80mm. I did mention the responsiveness of the smaller, skinnier and lighter tires that I was hoping not to lose totally.

[keen]

Originally Posted by bidaci

I am actually looking to get the benefit of the larger diameter tire for rollover of obstacles that I had with the larger 26" tires. My thoughts where I could get some of that back with the 650b without the extra weight of fat tires (as well as some more air volume for lower pressure). I may have not been clear on the original post but I cannot see where I wanted faster steering. That I could get by cranking the uturn down from 120mm to 80mm. I did mention the responsiveness of the smaller, skinnier and lighter tires that I was hoping not to lose totally.

650b will give better rollover. A 2.3 Pacenti Neo-moto weighs 750g, a 2.0 Quasi Moto weighs 550g - Going to be a bust in the weight arena compared to a light 26er. A skinnier tire w/ shorter knobs may improve steering response but in my opinion if responsivness is a concern a 650b on that frame isn't the way to go. When I run really grippy tires steering response slows but traction obviously improves. I ahve heard a quite a few reasons to consider a 650b but not light or more responsive i'd say the opposite compared to a 26er.

[105millimetersofpleasure]

Originally Posted by bidaci

I am actually looking to get the benefit of the larger diameter tire for rollover of obstacles that I had with the larger 26" tires. My thoughts where I could get some of that back with the 650b without the extra weight of fat tires (as well as some more air volume for lower pressure). I may have not been clear on the original post but I cannot see where I wanted faster steering. That I could get by cranking the uturn down from 120mm to 80mm. I did mention the responsiveness of the smaller, skinnier and lighter tires that I was hoping not to lose totally.

Seems like worrying about a few oz of weight on a Giant AC might be counter productive. If you're seeking more stability, build up a 650b front wheel and play around with the U turn adjustment.

I have a front 650b wheel here that's collecting dust while I wait for backordered frame parts, so if you're in the SF East Bay and you're not a clydesdale (stan's 355 rim), let me know and we'll figure out a way for you to try it on your bike in the next week or so.

josh

[bidaci]

Originally Posted by 105millimetersofpleasure

Seems like worrying about a few oz of weight on a Giant AC might be counter productive. If you're seeking more stability, build up a 650b front wheel and play around with the U turn adjustment.

I have a front 650b wheel here that's collecting dust while I wait for backordered frame parts, so if you're in the SF East Bay and you're not a clydesdale (stan's 355 rim), let me know and we'll figure out a way for you to try it on your bike in the next week or so.

josh

I appreciate the offer but I am up in the Boston area.

I agree that weight cannot be the primary concern, but I will say that taking 1.5 lbs of rotating mass off of each wheel (with the smaller tires) is a major improvement in overall responsiveness with the bike. As far as going to the 650b, if I won't see any weight savings over the Kujo DH (2350g front wheel assy) then there is no real reason to go to the 650b as the diameter does not seem to be much different then the Quasimoto 2.0.

I guess I will just try to get my hands on a 650b wheelset and try it out front and rear.

[JMac47]

Same idea here. I have a 100mm 26" frame. If I use a 650 up front and drop to a 80mm fork will it pretty much balance everything back out? Generic question I know but thinking along these lines.

Thx in advance-Jmac

[TNC]

Originally Posted by JMac47

Same idea here. I have a 100mm 26" frame. If I use a 650 up front and drop to a 80mm fork will it pretty much balance everything back out? Generic question I know but thinking along these lines.

Thx in advance-Jmac

Honestly, I think you guys may be obsessing about the effect of the 650B/26 setup on many bikes. I've done an SC Nomad and an '08 Spec Stumpjumper, and neither bike had screwball geometry or weird handling traits. In fact the opposite was true in both cases. They are better for the mod. We've even done some interesting 69'ers at our shop then ended up working amazingly well. I won't claim to knowing exactly why today's bikes don't seem quite as touchy about manipulating their geometries, but I find that's the case quite frequently.

[JMac47]

Originally Posted by TNC

Honestly, I think you guys may be obsessing about the effect of the 650B/26 setup on many bikes. I've done an SC Nomad and an '08 Spec Stumpjumper, and neither bike had screwball geometry or weird handling traits. In fact the opposite was true in both cases. They are better for the mod. We've even done some interesting 69'ers at our shop then ended up working amazingly well. I won't claim to knowing exactly why today's bikes don't seem quite as touchy about manipulating their geometries, but I find that's the case quite frequently.

Just like the way it rides now but want the benifit of the bigger wheel without the flop factor.

[keen]

Originally Posted by JMac47

Just like the way it rides now but want the benifit of the bigger wheel without the flop factor.

I think it really depends how sensetive you are to wheel flop. I rode DH bikes for years w/ 65-67* HA's and never gave any thought to wheel flop or slow steering. Fast forward a number of years I have been riding trail bikes w/ 68-70* HA's and now I can really feel the effects of a slack bike. My current ride had a 68* HA w/ 26" wheels went 650b front only and really could feel the steering slow. I went to the 650b rear and it sped of the steering, not as much as the 26er's but I could live with it. The 650b was only roughly 1/2" taller than my 26er but the " trail" angle also changes. Maybe if my bike had a 70ish* HA it wouldn't have been as noticable but like I said depends on your sensetivity level.

[bidaci]

Originally Posted by TNC

Honestly, I think you guys may be obsessing about the effect of the 650B/26 setup on many bikes. I've done an SC Nomad and an '08 Spec Stumpjumper, and neither bike had screwball geometry or weird handling traits.

The geo doesn't bother me. My obsession is with wieght

[JMac47]

Originally Posted by 105millimetersofpleasure

I have a front 650b wheel here that's collecting dust while I wait for backordered frame parts, so if you're in the SF East Bay and you're not a clydesdale (stan's 355 rim), let me know and we'll figure out a way for you to try it on your bike in the next week or so.

josh

When you back over Annadel/China Camp way?? I'd appreciate throwing the 650 on front for a trial spin. You know I'M not a clyde! PM me if interested.

Jeff

[JMac47]

Originally Posted by keen

Maybe if my bike had a 70ish* HA it wouldn't have been as noticable but like I said depends on your sensetivity level.

17" 100mm fork frame geo w/ 71* head angle. I run a tall WTB WW 2.55LT in back anyway so that should help to level the back end up with the trail I would think. I will be running a 2.1 up front either Neo, Nev or Wolverine if it ever comes oout in production.

[salimoneus]

Does anyone else believe that this particular configuration (and 69er as well) just isn't all that interesting? I mean, if the problem is that the wheels are too big, or too small, adjusting only one is only solving half the problem.

It seems to me that you'd be better off going either both 650b or both 26". With a mismatch, you still end up driving a back wheel size that will not match the abilities of the front. If you're able to "roll over" obstacles with a 650b front, why would you want to leave a 26" in back since you already know it's too small to do the same thing? It still has to climb over the same obstacle right?

I don't recall ever seeing any other offroad vehicles like dirtbikes or 4-wheelers or Jeeps that have mismatched wheel sizes front/back.

[umarth]

Originally Posted by salimoneus

Does anyone else believe that this particular configuration (and 69er as well) just isn't all that interesting?

You should try it. I think big wheels are necessary in the front, but the small disadvantage of traction/rollover in having a 26" wheel in the back is more than made up from its ability to speed. Currently I have 650b front and back (SS), and while it is a little smoother and traction is better, which is why I have it on for the wet season, when it gets dry, the smaller wheel helps me power through technical uphills. It doesn't seem to matter quite as much on flats and downhills either way.

To date it is my only mixed wheel experience, but I've liked it better than full 26/650/29er.

[88 rex]

Originally Posted by salimoneus

I don't recall ever seeing any other offroad vehicles like dirtbikes or 4-wheelers or Jeeps that have mismatched wheel sizes front/back.

Are you trolling for giggles or are you serious?

The set-up works well.

[salimoneus]

Originally Posted by 88 rex

Are you trolling for giggles or are you serious?

The set-up works well.

I guess I just don't follow the logic when someone says "well the front rolls over stuff better with the bigger tire" but somehow the rear wheel is exempt from doing the same. Just because it's a drive wheel doesn't mean it also wouldn't roll over stuff better/smoother.

Honestly this seems like more of a hack for frames that just won't accept a 650b in back, more than being an optimal setup.

[88 rex]

Originally Posted by salimoneus

I guess I just don't follow the logic when someone says "well the front rolls over stuff better with the bigger tire" but somehow the rear wheel is exempt from doing the same. Just because it's a drive wheel doesn't mean it also wouldn't roll over stuff better/smoother.

Honestly this seems like more of a hack for frames that just won't accept a 650b in back, more than being an optimal setup.

It's not that simple............or maybe it is. I'm not sure. It seems that this set-up doesn't appeal to you and considering your already lack of interest in the set-up I'm not going to try an describe its merits. It's not that I don't think 29" in the rear is bad, but I see the advantages of the "smaller" rear tire with shorter chainstays.

I will add though, if your front tire gets hung up you are going over the bars or severly killing momentum....with the rear, not so much. Think about it, and think about weight distribution.

[TNC]

Originally Posted by salimoneus

I guess I just don't follow the logic when someone says "well the front rolls over stuff better with the bigger tire" but somehow the rear wheel is exempt from doing the same. Just because it's a drive wheel doesn't mean it also wouldn't roll over stuff better/smoother.

Honestly this seems like more of a hack for frames that just won't accept a 650b in back, more than being an optimal setup.

sal, ever wonder why dirt motors have generally settled on a taller wheel up front and a shorter wheel out back?...in the case of my dirt motor, 21"/18". The total tire and wheel measurement comes to 27.5"/25.5". Remember back when they even tried to go to a 23" front wheel, but it ate up too much travel in the fork and/or dinked up the geometry too much?

A taller front wheel is an accepted method of achieving positive handling and suspension characteristics for off road applications for 2-wheel vehicles. There are always exceptions and arguments for other applications, but your question revolved around how or why a taller front, shorter back would be logical. Well, somehow it works quite well for a dirt motorcycle, and I point to it rather than go through a long and boring physics class about how the front wheel dynamics differ in hitting obstacles as opposed to the rear wheel. They are not equal in their dynamics. Now...on the other hand, your statement about the rear wheel being tall also is true in that it will probably improve rollover in most all cases. Wheel selection and sizing have a myriad of influences, and you can't just focus on one.

[salimoneus]

Originally Posted by TNC

sal, ever wonder why dirt motors have generally settled on a taller wheel up front and a shorter wheel out back?...in the case of my dirt motor, 21"/18". The total tire and wheel measurement comes to 27.5"/25.5". Remember back when they even tried to go to a 23" front wheel, but it ate up too much travel in the fork and/or dinked up the geometry too much?

A taller front wheel is an accepted method of achieving positive handling and suspension characteristics for off road applications for 2-wheel vehicles. There are always exceptions and arguments for other applications, but your question revolved around how or why a taller front, shorter back would be logical. Well, somehow it works quite well for a dirt motorcycle, and I point to it rather than go through a long and boring physics class about how the front wheel dynamics differ in hitting obstacles as opposed to the rear wheel. They are not equal in their dynamics. Now...on the other hand, your statement about the rear wheel being tall also is true in that it will probably improve rollover in most all cases. Wheel selection and sizing have a myriad of influences, and you can't just focus on one.

Actually I was under the impression that dirt bikes used the same sized wheels front and back. Looking at a few models online, I see that this is indeed not the case as the fronts are usually at least a couple inches larger. Thanks for pointing that out (the painfully obvious). Now I'm curious about it and am going to look for some info/discussion about exactly how it is beneficial. I'm not a physicist but do enjoy the technical aspects of these kinds of things.

That would be really nice if doing the front end conversion is just as if not more effective than a full 650b. I have been waiting for more selections in 650b FS frames to come out. Instead of going for a whole new rig, tossing on a new wheel and dialing down the fork (optionally?) seems like a pretty cheap way to get setup.

[umarth]

I'm reluctant to compare dirt bike to mountain biking because of the various discrepancies. Wheel sizes and set ups are intensely personal. Some people just don't care about what they ride, as long as they ride. Some like SS, some care about bike weight. I do know that I like, and I so I try to convey my own experiences for others. It is nice to find that others have had similar fun...

[reformed roadie]

Forget the comparison to motorcycles, though it is valid - I understand that not everyone has experience riding one.

Instead consider that for the most part, of you have any momentum, once you clear your front wheel over a log, root, rock garden, etc., you can clean it...for the most part. The rear wheel 'catching' is much less of an issue than the front. You can't go over the bars (duh).
You also have the option of applying power to the wheel to get it over.

When I had 26 F&R, I used to manual through everything...my front wheel was either up or just skimming whatever roots/rocks I encountered on the trail. With the 650b front, I find that is less of requirement. This is a positive for sections - tight, twisty - where lofting is impractical.

[salimoneus]

Originally Posted by reformed roadie

Forget the comparison to motorcycles, though it is valid - I understand that not everyone has experience riding one.

Instead consider that for the most part, of you have any momentum, once you clear your front wheel over a log, root, rock garden, etc., you can clean it...for the most part. The rear wheel 'catching' is much less of an issue than the front. You can't go over the bars (duh).
You also have the option of applying power to the wheel to get it over.

When I had 26 F&R, I used to manual through everything...my front wheel was either up or just skimming whatever roots/rocks I encountered on the trail. With the 650b front, I find that is less of requirement. This is a positive for sections - tight, twisty - where lofting is impractical.

I understand the benefits of having the front larger, but I'm still not clear on why having the rear the same would be a disadvantage. If the front now goes over obstacles easier, wouldn't the rear as well?

I'm sure there is just something I am not considering here. Maybe it's the simple fact that there is less rotational mass with a smaller wheel, and it's easier to spin up than a bigger wheel. And that outweighs any other apparent benefits?

[reformed roadie]

Well the thread is titled 26er w/ 650b front only...

650b doesn't fit in the back of my blurXC.

The beauty of the 650b front is it plugs right into the fork and for my bike, makes a positive change to the geometry, incl. more bb clearance.
The bike was IMHO too steep to begin with...I could say this is more than just my opinion, as SC sleckened the new bike's HA.

not sure if I would go to 650b f&r, for the reason you mention - weight.
From a practicality standpoint, I have 3 26" rear wheels, and stacks of 26" tires to wear out first.

[88 rex]

Originally Posted by salimoneus

I understand the benefits of having the front larger, but I'm still not clear on why having the rear the same would be a disadvantage. If the front now goes over obstacles easier, wouldn't the rear as well?

I'm sure there is just something I am not considering here. Maybe it's the simple fact that there is less rotational mass with a smaller wheel, and it's easier to spin up than a bigger wheel. And that outweighs any other apparent benefits?

For me.. it's frame geometry and weight.

And the rear is not a disadvantage for "roll overability." It's just not as big an advantage as it is for the front.

This is all my opinion, and my opinion is based upon my riding style.

[salimoneus]

Originally Posted by reformed roadie

Well the thread is titled 26er w/ 650b front only...

650b doesn't fit in the back of my blurXC.

Which kindof goes back to my original assertion..

Honestly this seems like more of a hack for frames that just won't accept a 650b in back, more than being an optimal setup.

It's entirely possible that if your frame would fit a 650b rear you would be raving about it's advantages just like the front.

I am just wondering if people are mostly running this because they have no other choice, or because even though they could run both they feel this is a better configuration.

The fact that dirtbikes run with mismatching wheel sizes does say something to me about it's validity though. I just need to go and do some digging to find out exactly why that is.

[TNC]

Originally Posted by salimoneus

Which kindof goes back to my original assertion..



It's entirely possible that if your frame would fit a 650b rear you would be raving about it's advantages just like the front.

I am just wondering if people are mostly running this because they have no other choice, or because even though they could run both they feel this is a better configuration.

The fact that dirtbikes run with mismatching wheel sizes does say something to me about it's validity though. I just need to go and do some digging to find out exactly why that is.

I have two bikes in 650B/26 setup. The Nomad won't take a 650B rear, but the '08/'09 SJ FSR will. I don't have 650B in the rear, because I like the slightly easier spinup capability of the shorter wheel. We've had/have several bike setups at the shop that are full 650B front and rear. For me in tighter, technical terrain, taller wheels are more difficult for me to accelerate, and it becomes more evident when the rear wheel is taller. Playing with different gear combos help but don't eliminate this issue for me. This is my weakness. This is not an absolute...it's a prefence. I'm not a 29'er fan for the same reason, though it's obvious the big wheel bikes are excellent for many riders.

Physics will generally support the better rollover characteristics of a taller wheel, but it is just one element in the package. For example the issue of better acceleration and spin was very evident with 24" rear wheel setups that were more common some years ago. Its achilles heel was being a little too short and succumbing to frequent hangup in technical terrain. The 26" wheel is a good compromise. Compromises come together to get the best package for a given rider, on a given bike, in a given situation. Mine is 650B/26". Others can vary greatly.

[reformed roadie]

Originally Posted by salimoneus

Which kindof goes back to my original assertion..

It's entirely possible that if your frame would fit a 650b rear you would be raving about it's advantages just like the front.

I am just wondering if people are mostly running this because they have no other choice, or because even though they could run both they feel this is a better configuration.

Well...consider the 69er. Clearly the rollover ability of the front is more important than the rear, and the 26" rear accelerates faster.
Combine that with the trend towards slacker HT angles, and the compatibilty w/ common OEM forks (read FOX)...it makes sense for me and many others.
Tire choice is limited, but fortunately, many are good choices.

If you do try it, make sure you adjust your position before writing it off.