Rear wheel rubbing

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joniboi
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Rear wheel rubbing

Postby joniboi » Thu Oct 04, 2012 21:12 pm

Hi,
Since my brake lines have been tightened (on my fairly new bike) I've noticed my rear wheel rubs on the brake blocks when climbing, is this unusual? Is it something to be concerned over?
Thanks,

Jb.

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ALIHISGREAT
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Re: Rear wheel rubbing

Postby ALIHISGREAT » Thu Oct 04, 2012 21:32 pm

It can be 'normal' depending on the flexibility of the wheels and frame.

I know my Giant Defy 1 suffered from it when I was lugging my 82kg up a steep Cat 4. (only realised after washing when the rim would squeak though -> its not a massive issue)

It can also be a problem if the wheels are not running true.

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smidsy
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Re: Rear wheel rubbing

Postby smidsy » Fri Oct 05, 2012 04:51 am

You now have the perfect excuse for a new set of wheels Sir :-)
Yellow is the new Black.

neeb
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Re: Rear wheel rubbing

Postby neeb » Fri Oct 05, 2012 05:42 am

It's a question of degree really. Even with the stiffest wheels/frame you will get some rubbing when climbing out of the saddle if you adjust the brake blocks to be a fraction of a mm from the rim. In general it's not something to be worried about unless you have to set the brakes too far away from the rim for responsive braking. Wheel lateral stiffness is a different thing from radial/torsional stiffness, which in many ways is more important on the rear wheel.

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diy
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Re: Rear wheel rubbing

Postby diy » Fri Oct 05, 2012 07:19 am

You could always slacken the rear off a bit to increase the space. Its the front that does the stopping any way. I would check you QR are tight and there is no play in the bearings too.

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Ron Stuart
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Re: Rear wheel rubbing

Postby Ron Stuart » Fri Oct 05, 2012 10:35 am

First check wear on bearings then if slack then tighten but just enough to still let the wheel run free but with minimum side play.
If still a problem then have spoke tension checked properly, not all mechanics have this particular skill though best go recommended if possible.
If still a problem then you have either a naff frame and or wheels and could mean time to go shopping for one or other or both. You could do with independent trustworthy advice here. :wink:

racingcondor
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Re: Rear wheel rubbing

Postby racingcondor » Fri Oct 05, 2012 12:12 pm

As said, it depends on the wheels. If you get it a lot then you should probably be looking at stronger wheels (a lot of flex won't do anything for the spoke life).

I get it on RS80's and my SRAM AL30's and put this down to a stiff rim with few spokes (the rim is stiff enough to reist lateral forces but with 20 spokes they stretch instead). Don't get it at all on my overbuilt 32 spoke Open Pro / Ultegra build.

I don't think it's really a huge problem though. I've seen enough pre-sprint footage to see pro's on Zipps open up the rear brake before a sprint.

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Ron Stuart
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Re: Rear wheel rubbing

Postby Ron Stuart » Fri Oct 05, 2012 15:46 pm

racingcondor wrote:As said, it depends on the wheels. If you get it a lot then you should probably be looking at stronger wheels (a lot of flex won't do anything for the spoke life).

I get it on RS80's and my SRAM AL30's and put this down to a stiff rim with few spokes (the rim is stiff enough to reist lateral forces but with 20 spokes they stretch instead). Don't get it at all on my overbuilt 32 spoke Open Pro / Ultegra build.

I don't think it's really a huge problem though. I've seen enough pre-sprint footage to see pro's on Zipps open up the rear brake before a sprint.


There is absolutely no way that any pro rider would be using as a matter of course any form of equipment that resulted in the wheels rubbing on the brake pads when climbing, sprinting or whatever, what's more I wouldn't. The common reason why riders in the pro peloton open there brake calipers is because quite often when changing a wheel in a hurry particularly the rear which is more difficult to aline the mechanic hits the brake pads with the tyre and the calipers move so the rider opens the calipers to compensate.
Wheels especially expensive ones should never rub the pads under normal ( Big Maggy Use) if they do then there is something wrong with the set up as I previously posted.

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MountainMonster
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Re: Rear wheel rubbing

Postby MountainMonster » Sat Oct 06, 2012 00:16 am

Ron Stuart wrote:
racingcondor wrote:As said, it depends on the wheels. If you get it a lot then you should probably be looking at stronger wheels (a lot of flex won't do anything for the spoke life).

I get it on RS80's and my SRAM AL30's and put this down to a stiff rim with few spokes (the rim is stiff enough to reist lateral forces but with 20 spokes they stretch instead). Don't get it at all on my overbuilt 32 spoke Open Pro / Ultegra build.

I don't think it's really a huge problem though. I've seen enough pre-sprint footage to see pro's on Zipps open up the rear brake before a sprint.


There is absolutely no way that any pro rider would be using as a matter of course any form of equipment that resulted in the wheels rubbing on the brake pads when climbing, sprinting or whatever, what's more I wouldn't. The common reason why riders in the pro peloton open there brake calipers is because quite often when changing a wheel in a hurry particularly the rear which is more difficult to aline the mechanic hits the brake pads with the tyre and the calipers move so the rider opens the calipers to compensate.
Wheels especially expensive ones should never rub the pads under normal ( Big Maggy Use) if they do then there is something wrong with the set up as I previously posted.


Your English language skills are very poor, and why are you speaking about "pro peloton" when 98% of people on this forum are not pros, and will never be. They look to save milliseconds, which to us normal people means nothing.

For the op,have you tried re-centering the caliper to make sure that is in line?

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Ron Stuart
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Re: Rear wheel rubbing

Postby Ron Stuart » Sat Oct 06, 2012 07:49 am

MountainMonster wrote:
Your English language skills are very poor, and why are you speaking about "pro peloton" when 98% of people on this forum are not pros, and will never be. They look to save milliseconds, which to us normal people means nothing.

For the op,have you tried re-centering the caliper to make sure that is in line?


My English language skills are light years above your level of tact.

For the op, my reference to the "pro peloton" is to emphasize the fact that what is good for them should be more than good enough for the 98% of the rest of us and also believe or not I was trying to be helpful.

Don't be a coward and hide behind this media being rude to people, it only reflects badly upon yourself. :roll:

joniboi
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Re: Rear wheel rubbing

Postby joniboi » Sat Oct 06, 2012 18:33 pm

Thanks for your replies, I guess I'll try and see if it's a simple alignment problem and sort it out, otherwise just not worry about it from now on. One more question though.... As I was descending into Dartmouth a few days ago down the steep hill, I ended up going faster than I have been before (relatively new to this) 47 mph and my bike started to shake a slightly, a little scared by this point the brakes (gentle) seemed to exaggerate the problem before slowing me down to a more familiar speed and feel of the bike. It actually felt more like the front end shaking than the rear, is this something that just happens and you get used to, or should a bike run smoothly at any speed? The road surface is as far as I recall good.

Jb.

farrina
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Re: Rear wheel rubbing

Postby farrina » Sat Oct 06, 2012 19:12 pm

Think you need to read this posting

http://www.bikeradar.com/forums/viewtopic.php?f=40013&t=12877040

Yes is very disconcerting, especially as it seems to be a combination of circumstances that can cause it.

Only happened to me a couple of times over many decades, but terrifying when it does.

Regards

Alan
Regards
Alan

joniboi
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Re: Rear wheel rubbing

Postby joniboi » Sun Oct 07, 2012 19:25 pm

Thanks Alan, that's exactly it.
when you say a couple of times over many decades does this mean you have been at the same high speeds many times but it has only happened on very few occasions, or that you have only been at those speeds a couple of times?
If it's the former then that puts my mind at ease.....

Jb.


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