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I'm considering upgrading my GF Tarpon to a 27.5" wheelset. Is this possible? And how will affect the ride? In general, I've heard people say no, and some people say yes (nothing specific about this bike, though).

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Why do you want to do this?

The problem with switching wheel sizes is normally the brake mounting for rim brakes, and the tire clearances. I have a feeling that you won't be able to line up the rim brakes when you do this (if you had disc brakes, this would be simpler - if the rotor fits, it works). The following thread here says that Velo Orange's Grand Cru canti has enough adjustment for swapping 26" wheels to 650b wheels on some bikes (probably, but would require switching to short pull brake levers) and Paul's MotoBMX brakes may work as well. Your current brakes may or may not have enough adjustment to do this. This is all assuming of course you can even get the 650b wheel in with your desired tire. You could run a staggered setup (650b front, 26" rear) with a new fork at the worst, but this is expensive and likely would require you to adjust things due to the height difference.

A switch from 26" to 650b will move your bottom bracket up 1/2 an inch.

I think this conversion would be largely pointless, especially on a cheap bike like a Gary Fisher Tarpon. You're better off picking a better tire for your purposes unless you REALLY need the extra half inch of bottom bracket height (in which case, you should probably get a different bike). You'd have to buy new wheels and possibly new brakes, which puts you a good way towards just selling the bike and buying a 27.5" er to begin with.

On the other hand, Sheldon Brown points out that the 700c to 650b conversion can be useful.

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Thanks. I was also considering just buying a new bike. I think I will hold off and purchase a new bike. The GF has held up well. P.S. I would up vot but I dont have enough rep.. – SoilSciGuy Jan 27 '14 at 0:52

I don't believe this is possible for a number of reasons even if the back wheel fits:

  • Vee brakes would not work.
  • Unlikely to find a 650b wheelset with a 7 speed hub unless you get a custom set.
  • Would need a 650B or 29" fork.

For the cost of a new fork as wheel set you'd likely be able to find a comparably spec'd 650B.

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I'm not sure what you mean by the second point - you buy a 650B wheel set (they don't give you a cassette for free with them...), buy a 7 speed cassette, throw on the right spacer and go to town. The bigger issue is the brakes - I find it unlikely that a V brake would have enough adjustment to work with the swapped wheel, even if the wheel was able to be put in. People have done 26" -> 650b swaps though on things like Surly Long Haul Truckers. – Batman Jan 27 '14 at 0:50
The bigger issue is actually probably finding a 650B wheel with rim brakes these days (they exist, but aren't super duper common). – Batman Jan 27 '14 at 0:55
650b wheels for rim brakes aren't terribly uncommon. They're used in smaller sized road bikes and for rando/touring bikes and are gaining in popularity. You won't see big fat rims on them, but if you're riding big fat tires you're already one foot into the world of disc brake-equipped mountain bikes. – WTHarper Jan 27 '14 at 1:40
@Batman - Using a wider hub with a spacer is an option but not as simple as throwing on suggests. You end up having to set the limits on the RD and increase the risk of the chain going over the top end and getting jammed in between cassette and hub/spokes. Also the LHT is designed with far more flexibility and user preference than a cheaper MTB. Surly allow for far more customisation in their design. – DWGKNZ Jan 27 '14 at 20:54

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