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Old 07-31-09, 09:48 AM   #1
wr_uk
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Bontrager Ranger disc rims, 32h - Flexing when Braking

Hi I've just bought a Gary Fisher Piranha which has Bontrager Ranger disc rims, 32h. I've noticed that when I brake and rock the bike forward or backwards there is movement between the hub and the rim. Is this flexing through the spokes normal or not?
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Old 07-31-09, 10:03 AM   #2
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Think about this:
- With rim brakes, the braking force is transferred from the rim -> brake -> top of fork.
- With disc brakes, it is rim -> spokes -> hub -> brake -> bottom of fork.

Unless the wheel is constructed in one solid piece (eg Hed H3), there is bound to be flexing.
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Old 07-31-09, 10:14 AM   #3
wr_uk
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I have a trek 4300 and when I brake and rock that there is a not flexing with or should I say no abnormal flexing. Its rock solid. The term Flex I use is probably not the best term to use. on the gary fisher its more of a move (quarter- half inch) then a click like its hits something and same rocking back
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Old 07-31-09, 10:24 AM   #4
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I'd probably describe it as more of a more defined shift than a smooth flex
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Old 07-31-09, 01:54 PM   #5
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Originally Posted by wr_uk View Post
Hi I've just bought a Gary Fisher Piranha ..I've noticed that when I brake and rock the bike forward or backwards there is movement between the hub and the rim. Is this flexing through the spokes normal or not?
Unless the spokes are hopelessly undertensioned it'd be quite rare to have a visible flexing within the wheel components. Are you sure it isn't headset play you're seeing?
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Old 07-31-09, 01:59 PM   #6
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or fork dive
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Old 07-31-09, 02:05 PM   #7
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No head set is rock solid.

I did a quick test I swapped my wheels from the 4300 to the Piranha, and the problem still existed so that tells me the wheel is not the issue here and the brake housing is all tight so I can only assume that there is too much movement in the brake pads.

Is there any ways to correct this so there not too much movement with the pads?
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