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Old 09-28-06, 10:16 AM   #1
rodfrank
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wheel sizes

Looking for a discussion or comments on the pluses and minuses of the following wheel size combinations 26/20, 26/26, 20/20. Apologies if this has already been done. Thanks... ( Touring and general riding).
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Old 09-28-06, 10:51 AM   #2
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I'd say the plus/minus depends on the frame. 26/26 would be a big no-no on my lowracer due to heel strike. Plenty of other examples, but they vary according to frame style.
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Old 09-28-06, 12:47 PM   #3
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Well, there are way more tires available for 26" wheels. A 20" rear wheel will require a special crankset to achieve the same speeds. Aside from that, the differences are negligible.
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Old 09-29-06, 05:33 PM   #4
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I was thinking in terms of efficiency
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Old 09-29-06, 08:25 PM   #5
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I think we'd need to define efficiency.
But assuming it's just speed
26x26 in theory ought to produce the highest speeds, but in practice...all of the really fast bikes seem to be faired, and most of them use at least one 20" wheel.

20x20 ought not to be the most efficient, but darned if I can tell any real difference between a Rocket and a VRex other than looks. Once you're on it, you can't see the back wheel.

The gearing of smaller wheels does take some thought. But if you can produce power over a reasonable RPM range, it's a non-issue.

26x20 is a decent compromise, but IMO, a lot of the supposed "really big differences" simply don't exist as other than placebo effect for anyone who rides less than 4k miles a year or so. If you ride more than that, you probably have a pretty good idea of what you want anyway.

Not real helpful, was it?
Just get the bike you think looks best & is most comfortable. You'll ride it more, and as a result you'll be faster than you'd otherwise be.
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Old 09-30-06, 04:04 PM   #6
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Thanks
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Old 09-30-06, 06:09 PM   #7
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I would think of it in terms of how deep a small tire falls into a pothole compared to a larger rim. Larger tires also hold more air so there is more air volume for absorbing bumps.

On the flipside, smaller wheels are lighter and are probably easier to store, depending on the frame they are mounted on.

The gearing of a small wheel is a serious consideration for achiving your desired gear-inch range.
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Old 09-30-06, 09:23 PM   #8
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Quote:
Originally Posted by Shaman
I would think of it in terms of how deep a small tire falls into a pothole compared to a larger rim. Larger tires also hold more air so there is more air volume for absorbing bumps.

On the flipside, smaller wheels are lighter and are probably easier to store, depending on the frame they are mounted on.

The gearing of a small wheel is a serious consideration for achiving your desired gear-inch range.
One theory - among many - goes like this: A 406 (20" BMX) tire in a decent width, say a 37, will have a nearly round contact patch. A 622 (aka 700c) in 25 might not. I'm not buying into the argument that simply going from 406 to 559 (20 to 26) will gain 2-3 mph. Maybe 1/4, maybe 1/42 or something. Whatever it is, I bet the difference is less than subtracting cheeseburger or adding 5 miles of riding a week, which goes back to the concept of "get a bike you like to look at, because you'll ride it more." It really is so.

I have a Rocket, and do not find a need for the 62 tooth ring. I've been able to get it to around 33mph on level ground in the 93" gear available in the middle ring (19.5" * 53/11) and feel that is sufficient for my needs.

It's late, but IIRC, cadence * gear inches * 0.002975 = speed in MPH... 110 RPM gives you 30mph. IMO, one really ought to be able to produce meaningful power up to 120 or so. 120" top gears are for guys who sprint to the lower 40's. Not me.
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Old 10-01-06, 07:40 AM   #9
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Quote:
Originally Posted by Shaman
I would think of it in terms of how deep a small tire falls into a pothole compared to a larger rim. Larger tires also hold more air so there is more air volume for absorbing bumps.

On the flipside, smaller wheels are lighter and are probably easier to store, depending on the frame they are mounted on.

The gearing of a small wheel is a serious consideration for achiving your desired gear-inch range.
Another consideration is that the smaller wheel has a shorter spoke run and that equates into greater strength.
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