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Recreational Cyclocross and Gravelbiking This has to be the most physically intense sport ever invented. It's high speed bicycle racing on a short off road course or riding the off pavement rides on gravel like :The Dirty Kanza". We also have a dedicated Racing forum for the Cyclocross Hard Core Racers.

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Old 03-23-09, 12:14 AM   #1
thirdin77
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rim width effect on ride quality

I couldn't find any posts on this in particular.

My Tricross Sport came with Alex rims with a 17mm internal width and I've been wondering if the wider rim doesn't allow my 700x32 Specialized Borough Sport tires' sidewalls to bulge as much as a narrower rim would, thereby reducing the "spring" effect of the tire's sidewalls.

Would going to a 15mm internal width rim give me noticeably better ride quality?

I would be going from a 622x17 32-spoke 3-cross wheel to a 622x15 32-spoke 3-cross wheel.

I'm also thinking about more permanently using 700x28 Conti Gatorskins on pavement.

Would the 17mm rims give a harsher ride then 15mm rims when used with 700x28 Gatorskins?


Here's a cut & paste spec of my wheelset & tires:
RIMS
Alex ACE-19 double wall rim, CNC sidewalls, spoke eyelets, 32h
FRONT HUB
Specialized forged alloy, 32h, sealed bearings, QR
REAR HUB
Specialized forged alloy, 32h, sealed ball bearings, cassette, QR
SPOKES
Stainless 14g
FRONT TIRE
Specialized Borough Pro CX, 700x32c, aramid bead, 120TPI
REAR TIRE
Specialized Borough Sport CX, 700x32c, wire bead, 60TPI


I'm running the 120TPI tire on the front because I got 2-3 flats with it when I ran it on the rear. So far only 1 flat with it on the front. This tire's puncture resistance is lousy.
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Old 03-23-09, 07:49 AM   #2
flargle
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Would the 17mm rims give a harsher ride then 15mm rims when used with 700x28 Gatorskins?
No. What gives "springiness" to a tire is the volume and pressure of air, not the shape of the sidewall. You are thinking of the sidewall as analogous to a steel spring but it doesn't work that way.

http://sheldonbrown.com/tire-sizing.html#width
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Old 03-23-09, 12:13 PM   #3
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Wider rim will flatten out the tire. It will have more influence on how you corner. However, 32cs could definitely be mounted on a slightly larger rim.
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Old 03-23-09, 02:30 PM   #4
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I've run the same 32c cross tire on both road (15mm inside width) and wider rims (17mm inside). I would say the the wider rim allows for more confident corning and causes the tire profile to be more round as opposed to oval.

You should be fine running 28 or 32c tires on either rim though.
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Old 03-23-09, 04:54 PM   #5
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I've run the same 32c cross tire on both road (15mm inside width) and wider rims (17mm inside).
This is just the experience I was looking for. Did you notice any difference in ride quality?

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I would say the the wider rim.. causes the tire profile to be more round as opposed to oval.
I was wondering if the rounder profile allows the tire to be more shock-absorbent.
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Old 03-23-09, 05:03 PM   #6
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Not ride difference. More control due to less flexy sidewall movement on the wider rim though. The sidewall is straight up on the rim as oppose to moving away from the rim and back on top.

On the 17mm rim, you shouldn't install 23c tires.
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