So WTB announces a new 650B tire for gravel. This got me thinking... Has anyone else with a cross bike or gravel bike changed wheel sizes to 650B and been able to run larger tires sizes than would previously fit? I know people are doing this with MTN bikes and Fargos but haven't heard much in the gravel scene. Is anyone doing this and does it help?
I have a Habenero Ti bike that I am running 650b on and my wife has a Salsa Ti Vaya running 650b also. We ride gravel all the time with this setup. I can run up to 52mm tires and she can run 48s. We both love the bikes with these wheels. I run 700c on mine on the road and switch back and forth with no issues.
Unless I'm mistaken, this would only allow a taller tire due to smaller rim diameter, but not necessarily a wider one since that would still be limited by chainstay/fork clearance. Correct?
The stays and fork blades get wider as you move closer to the axle so you can usually get a wider tire too, depending on how your frame is constructed.
You could try contacting Jan Heine at http://www.bikequarterly.com/. He is a big 650B advocate and just published his second review of the Diverge in his current issue.
BWV 211 wrote:You could try contacting Jan Heine at http://www.bikequarterly.com/. He is a big 650B advocate and just published his second review of the Diverge in his current issue.
I haven't converted anything, but my I had my rando/touring frame made for 650b, 42-56mm. In general, highly recommended. There's a bunch of really nice tires in the 38-50mm range now.
The outer diameter of an inflated 650x42mm is very very close to that of a 700x23mm, for reference. Just be aware of the effect a conversion will have on BB height.
Good point about the BB height, even though a mid width 650b tire will have a diameter close to a narrow 700c tire, there will be more drop due to the larger tire compressing more under load.
\n
\n650b x 42mm tire:
\n584mm rim, plus 42mm tire = 334mm radius, minus 20% tire compression under load = 326 mm axle height.
\n
\n700c x 24mm tire:
\n622 mm rim, + 24 mm tire = 335 mm , -20% drop, = 330 mm axle height
\n
\nSo, for these two random, but common sizes, the 650b option lowers your bottombracket by 4mm, a notable change, but perhaps welcome for increased stability in gravel and sand.
Slim wrote:Good point about the BB height, even though a mid width 650b tire will have a diameter close to a narrow 700c tire, there will be more drop due to the larger tire compressing more under load.\n\n650b x 42mm tire:\n584mm rim, plus 42mm tire = 334mm radius, minus 20% tire compression under load = 326 mm axle height.\n\n700c x 24mm tire:\n622 mm rim, + 24 mm tire = 335 mm , -20% drop, = 330 mm axle height\n\nSo, for these two random, but common sizes, the 650b option lowers your bottombracket by 4mm, a notable change, but perhaps welcome for increased stability in gravel and sand.
\nA 4mm BB height difference is nothing.\nBut with gravel bikes the comparison should be with 700x32mm+ tires, not 24s (24mm is "common"?). Then there is a significant change, though it is still a minor factor in stability. The overall bike geometry, setup, frame construction, and component choice all work together to make a bike stable (and every other handling trait). Any single spec does not define how it works.\n\nI use everything from 650Bx38 - 650Bx2.25" to 700x28 - 29x2.0" on the same bike, with various different wheels. Yes, the handling changes, mostly because of the tire changes (tread, width, weight, casing). But the basic stability where flotation is not a factor is unchanged with the different BB heights. With the same type tread and width, the difference between 700C and 650B is minor. The former is less agile, which some riders may describe as more stable. Combo of diameter and weight. Both track well, the latter is easier to steer around hazards.
Had a bike last year rode nothing but 650b. Changed up bikes, went back to 700c. But now I'm trying 650b again. I'm thinking 650b for certain conditions. On the Planet X (though they would fit fine) there would be terrible toe overlap with 700X42c. And you do lose some weight dropping to the smaller wheel and tire. I am currently trying out the PariMoto 650x42.
shiggy wrote: A 4mm BB height difference is nothing. But with gravel bikes the comparison should be with 700x32mm+ tires, not 24s (24mm is "common"?). Then there is a significant change, though it is still a minor factor in stability. The overall bike geometry, setup, frame construction, and component choice all work together to make a bike stable (and every other handling trait). Any single spec does not define how it works. I use everything from 650Bx38 - 650Bx2.25" to 700x28 - 29x2.0" on the same bike, with various different wheels. Yes, the handling changes, mostly because of the tire changes (tread, width, weight, casing). But the basic stability where flotation is not a factor is unchanged with the different BB heights. With the same type tread and width, the difference between 700C and 650B is minor. The former is less agile, which some riders may describe as more stable. Combo of diameter and weight. Both track well, the latter is easier to steer around hazards.
Shiggy - thanks for the comments and making the point that bike components spec's should always be considered in the context of a surprisingly complex mechanical system. I enjoy your posts and find them very informative -- even when the expose the BS content of some of my own musings here.
I am currently trying out the PariMoto 650x42.