General Discussion Triathlon Talk » Problem with rear tire dragging on Cervelo P2C Rss Feed  
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2009-08-06 9:07 AM

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Subject: Problem with rear tire dragging on Cervelo P2C
Hi all, hopefully someone can help me out with this problem.  I recently replaced the rear tire on my Cervelo P2C with the same tire the bike came with (Vittoria Rubino Pro Slick).  It appears there is a problem with the tire dragging on the frame though where it wraps around the tire.  I can hear it squeak fairly loudly, particularly when more of my weight is shifted rear, like when I am not in the aero bars or climbing a hill standing out of the saddle.  The rear wheel appears to be true and none of the spokes are broken or anything, so I am not sure what to do.  Is there some sort of adjustment that can be done to the rear wheel positioning relative to the frame to prevent this?  Thanks


2009-08-06 9:24 AM
in reply to: #2331371

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Subject: RE: Problem with rear tire dragging on Cervelo P2C
Is it the same size tire? Did you replace a 700x23 with a 700x23?
2009-08-06 9:24 AM
in reply to: #2331371

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Subject: RE: Problem with rear tire dragging on Cervelo P2C
There are adjustment screws within the horizontal dropouts, the part of the frame where the rear wheel attaches via the skewers. Back those screws out (there is one in each dropout), maybe a half turn each until the tire no longer rubs on the frame cutout.

Recently had this problem, adjustment screws were set for the stock wheel, but I then put on my Renn disc. Turns out the Renn has a good bit of flex, especially when you apply power to accelerate or climb. It was in those cases that it would rub on the cutout. Had to back out the screws two full turns to get it to stop.

My related question is how much space can you have between that cutout and the rear wheel, and still realize most of the aerodynamic benefit?
2009-08-06 10:28 AM
in reply to: #2331371

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Subject: RE: Problem with rear tire dragging on Cervelo P2C
Ok thanks for the suggestion, will give that a try!  Obviously still have some stuff to learn about bikes.  And yeah I replaced like with like (700x23 with 700x23)
2009-08-06 1:49 PM
in reply to: #2331371

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Subject: RE: Problem with rear tire dragging on Cervelo P2C
had the same issue...  do what bear said and you should be good to go.
2009-08-06 7:26 PM
in reply to: #2331444

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Subject: RE: Problem with rear tire dragging on Cervelo P2C
the bear - 2009-08-06 9:24 AMThere are adjustment screws within the horizontal dropouts, the part of the frame where the rear wheel attaches via the skewers. Back those screws out (there is one in each dropout), maybe a half turn each until the tire no longer rubs on the frame cutout.

Recently had this problem, adjustment screws were set for the stock wheel, but I then put on my Renn disc. Turns out the Renn has a good bit of flex, especially when you apply power to accelerate or climb. It was in those cases that it would rub on the cutout. Had to back out the screws two full turns to get it to stop.

My related question is how much space can you have between that cutout and the rear wheel, and still realize most of the aerodynamic benefit?
I would like to know this as well.


2009-08-06 7:35 PM
in reply to: #2331371

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Subject: RE: Problem with rear tire dragging on Cervelo P2C
FYI, in case this should happen to you in the future.  I swapped from a 20mm to a 23mm rear tire thus having to back out the screws.  HOWEVER, my set screws slowly moved their way back in to the horizontal dropouts, thus causing the rear wheel rub in the cut-out (1 day prior to IMLP)...so...to fix this / prevent this:

1) You can use ball bearings in place of the set screws, such as wheel / headset bearings of different size....I am told it's an old track riders secret,

but I would choose option two....

2) cut a bic pen spring in half, or if you have to, use a full spring per set screw.  Place the set screw through the spring and then screw the set screw back in until you reach the desired depth of the rear wheel to the cut out.  The spring itself will help by placing tension on the set screw so it does not wiggle itself back into the frame causing clearance problems with your rear wheel.

Hope some of this helps if you have similar problems in the future.  Good luck.
2009-08-07 12:02 AM
in reply to: #2331371


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Subject: RE: Problem with rear tire dragging on Cervelo P2C
didn't know that.. thanks for the info
2009-08-07 10:01 AM
in reply to: #2331371

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Subject: RE: Problem with rear tire dragging on Cervelo P2C
Good tip on the spring, I'll have to give that a try.
2009-09-10 3:17 PM
in reply to: #2333132

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Subject: RE: Problem with rear tire dragging on Cervelo P2C
WanabSpeedy - 2009-08-06 7:35 PM FYI, in case this should happen to you in the future.  I swapped from a 20mm to a 23mm rear tire thus having to back out the screws.  HOWEVER, my set screws slowly moved their way back in to the horizontal dropouts, thus causing the rear wheel rub in the cut-out (1 day prior to IMLP)...so...to fix this / prevent this:

1) You can use ball bearings in place of the set screws, such as wheel / headset bearings of different size....I am told it's an old track riders secret,

but I would choose option two....

2) cut a bic pen spring in half, or if you have to, use a full spring per set screw.  Place the set screw through the spring and then screw the set screw back in until you reach the desired depth of the rear wheel to the cut out.  The spring itself will help by placing tension on the set screw so it does not wiggle itself back into the frame causing clearance problems with your rear wheel.

Hope some of this helps if you have similar problems in the future.  Good luck.


When I first read this, I thought "why would anybody waste their time doing this?"

I changed my tire (same size 23c), got wheel rub, backed out the screws, which promptly backed right back in, and now I'm in the process of destroying 2 BIC pens. Go figure.

Thanks for the tip though - that's a great idea!

 
2009-09-10 4:00 PM
in reply to: #2332292

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Subject: RE: Problem with rear tire dragging on Cervelo P2C
Boom808 - 2009-08-06 11:49 AM had the same issue...  do what bear said and you should be good to go.


Me too, mostly when I was making out of the saddle efforts.  I turn or so of the screws and it was all good.

BTW, I have as yet to run into the problems that the screws move back into the frame.  The spring idea seems logical, but I have yet needed the fix.


2010-05-25 1:22 PM
in reply to: #2399598

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Subject: RE: Problem with rear tire dragging on Cervelo P2C
How exacting do you have to be when adjusting the screws?

Im just wondering if its easy enough to do myself in a couple minutes or if I should bring into the LBS since the bike is only a couple months old?
2010-05-25 2:02 PM
in reply to: #2881085

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Subject: RE: Problem with rear tire dragging on Cervelo P2C
nhunter344 - 2010-05-25 1:22 PM How exacting do you have to be when adjusting the screws?

Im just wondering if its easy enough to do myself in a couple minutes or if I should bring into the LBS since the bike is only a couple months old?


You can easily do it yourself, just try to back out each screw (one in each dropout) by the same amount. Start with like a half-turn each time until you get it where it doesn't rub.
2010-05-25 2:23 PM
in reply to: #2881203

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Subject: RE: Problem with rear tire dragging on Cervelo P2C
Thanks for the tip!

My problem isnt the wheel rubbing, but sand, grime, dirt rubbing while riding in wet conditions. Id just like to give it a little more space so that Im not running a grinder against my cut-out.
2010-05-25 7:12 PM
in reply to: #2331371

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Subject: RE: Problem with rear tire dragging on Cervelo P2C
Unfortunately, spring doesn't work too well - it'll break sooner rather than later.

The key to eliminating the wheel-suck into the frame is to really, really tighten that back QR. Like nearly as tight as maximum. It should be so tight that it won't slip forward even with maximum power pedaling. The limit screws are not designed to hold a forward-slipping wheel - they are just meant to help you line up the wheel when you're putting it on. THe super-tight QR is the key. I learned this hard way, after springs, 2 sets of limiter screws, and a stripped screw casing. 
2010-05-26 8:30 AM
in reply to: #2331371

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Subject: RE: Problem with rear tire dragging on Cervelo P2C
Thanks everyone for the tips!

Took me about 5 minutes to fix the problem yesterday. Now I just have to make sure I have the QR nice and tight and I should be good to go.


2010-05-26 9:12 AM
in reply to: #2881996

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Subject: RE: Problem with rear tire dragging on Cervelo P2C
agarose2000 - 2010-05-25 7:12 PM Unfortunately, spring doesn't work too well - it'll break sooner rather than later.

The key to eliminating the wheel-suck into the frame is to really, really tighten that back QR. Like nearly as tight as maximum. It should be so tight that it won't slip forward even with maximum power pedaling. The limit screws are not designed to hold a forward-slipping wheel - they are just meant to help you line up the wheel when you're putting it on. THe super-tight QR is the key. I learned this hard way, after springs, 2 sets of limiter screws, and a stripped screw casing. 


I've had mine for over a year without any special super-tightening of the skewer, and have experienced no slippage. YMMV, and apparently did.
2010-05-26 9:21 AM
in reply to: #2331371

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Subject: RE: Problem with rear tire dragging on Cervelo P2C

To keep it from moving, adjust the screws to where the wheel is not rubbing and you have the clearance that you need/want. Then add loctite or clear finger nail polish to the screws. This keeps the screws from moving. I learned this from the head mechanic for the BMC Pro Cycling team.

2010-05-26 2:33 PM
in reply to: #2331371

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Subject: RE: Problem with rear tire dragging on Cervelo P2C
I read this tread yesterday, thinking "weird, I have never heard a squeeking sound from my wheel like this." Then last night got a flat and fixed it on the road, from then on I heard this horrible squeeking sound but only when I was climbing out of the saddle up a significant grade.

Of course I knew exactly what it was from you awesome people here on BT!
I'm not sure wheather to call this foreshadowing, irony, rotten luck, or a huge coinsidence but I'm glad I read this thread. Thanks for all of the inadvertent help.
2013-04-08 2:02 PM
in reply to: #2883995

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Subject: RE: Problem with rear tire dragging on Cervelo P2C
Yesterday I took my 2012 P2 out for the first real ride (3.5 hrs) and heard this noise under the same circumstance.  I am so glad someone posted the answer 5 years ago.
2013-04-09 7:42 AM
in reply to: #2881203

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Subject: RE: Problem with rear tire dragging on Cervelo P2C

the bear - 2010-05-25 3:02 PM
nhunter344 - 2010-05-25 1:22 PM How exacting do you have to be when adjusting the screws?

Im just wondering if its easy enough to do myself in a couple minutes or if I should bring into the LBS since the bike is only a couple months old?


You can easily do it yourself, just try to back out each screw (one in each dropout) by the same amount. Start with like a half-turn each time until you get it where it doesn't rub.

Boy did I beat my head against the wall with my P2 and trying to get the race wheels on until I found out about the set screws.

This is definitely a DIY. Make sure they are both backed out the very close to the same distance or the wheel will be slightly off center. Also put something under the bike in case you go too far and it falls out. My house has restored floors from 1873, full of grooves and knots, and it took a LONG time to find it!



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