|
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
Front fork shudder / brake grab
Hi All,
I took my road bike out for its maiden voyage last night. The front brakes were grabbing and causing the front fork to shudder terribly. Basically unusable. The set-up is a Surly crosscheck frame and fork, Avid SD-5 brake (linear pull), Dia Compe 287V lever, Kool Stop salmon pads (used), Velocity Dyad rim. I did a newsgroup search and came up with some things to check out: - ensure rim is true, especially the vertical trueness - clean rim - check pad angle - check for play in calipers - check headset (already ruled out) - new pads - different wheel I'll try these things when I go home tonight, but from what I've read these problems can be hard to fix. Any other advice or suggestions would be appreciated. Regards, Anthony |
Ads |
#2
|
|||
|
|||
Front fork shudder / brake grab
On Wed, 9 Apr 2008 16:30:28 -0700 (PDT), Anthony DeLorenzo wrote:
Hi All, I took my road bike out for its maiden voyage last night. The front brakes were grabbing and causing the front fork to shudder terribly. Basically unusable. The set-up is a Surly crosscheck frame and fork, Avid SD-5 brake (linear pull), Dia Compe 287V lever, Kool Stop salmon pads (used), Velocity Dyad rim. I did a newsgroup search and came up with some things to check out: - ensure rim is true, especially the vertical trueness - clean rim - check pad angle - check for play in calipers - check headset (already ruled out) - new pads - different wheel I'll try these things when I go home tonight, but from what I've read these problems can be hard to fix. Any other advice or suggestions would be appreciated. Also check that the brake mounting bolt is tight - it's a beginner thing, but some people (like jim beam) do miss it. |
#3
|
|||
|
|||
Front fork shudder / brake grab
On Apr 9, 6:30*pm, Anthony DeLorenzo
wrote: Hi All, I took my road bike out for its maiden voyage last night. The front brakes were grabbing and causing the front fork to shudder terribly. Basically unusable. The set-up is a Surly crosscheck frame and fork, Avid SD-5 brake (linear pull), Dia Compe 287V lever, Kool Stop salmon pads (used), Velocity Dyad rim. I did a newsgroup search and came up with some things to check out: - ensure rim is true, especially the vertical trueness - clean rim rim AND pad. I like to sand or even use a wee box plane on used pads to refresh them. - check pad angle Crucial to have proper toe in, especially with Kool stops! Proper toe in makes LP brakes much less grabby. Again, Kool Stops are really fussy about this. - check for play in calipers Grease posts, install brake, torque down mounting bolts, and start with return spring screws turned all the way in, balance arms by loosening one or the other--this will give you better feel at the lever. |
#4
|
|||
|
|||
Front fork shudder / brake grab
On Apr 9, 7:34*pm, landotter wrote:
On Apr 9, 6:30*pm, Anthony DeLorenzo wrote: Hi All, I took my road bike out for its maiden voyage last night. The front brakes were grabbing and causing the front fork to shudder terribly. Basically unusable. The set-up is a Surly crosscheck frame and fork, Avid SD-5 brake (linear pull), Dia Compe 287V lever, Kool Stop salmon pads (used), Velocity Dyad rim. I did a newsgroup search and came up with some things to check out: - ensure rim is true, especially the vertical trueness - clean rim rim AND pad. I like to sand or even use a wee box plane on used pads to refresh them. - check pad angle Crucial to have proper toe in, especially with Kool stops! Proper toe in makes LP brakes much less grabby. Again, Kool Stops are really fussy about this. - check for play in calipers Grease posts, install brake, torque down mounting bolts, and start with return spring screws turned all the way in, balance arms by loosening one or the other--this will give you better feel at the lever. you say you ruled out the headset, how did you check to rule it out ? (or you are saying you are knowledgeable enough to be certain it is fine ) |
#5
|
|||
|
|||
Front fork shudder / brake grab
On Apr 9, 6:30*pm, Anthony DeLorenzo
wrote: Hi All, I took my road bike out for its maiden voyage last night. The front brakes were grabbing and causing the front fork to shudder terribly. Basically unusable. The set-up is a Surly crosscheck frame and fork, Avid SD-5 brake (linear pull), Dia Compe 287V lever, Kool Stop salmon pads (used), Velocity Dyad rim. I did a newsgroup search and came up with some things to check out: - ensure rim is true, especially the vertical trueness - clean rim - check pad angle - check for play in calipers - check headset (already ruled out) - new pads - different wheel I'll try these things when I go home tonight, but from what I've read these problems can be hard to fix. Any other advice or suggestions would be appreciated. Regards, Anthony Sure fix: stop the front brake housing at the bottom of the steerer tube (on the fork crown), not the top (in the headset). Redline bikes come with an aluminum bolt-on housing stop for this. This mod removes most of the steerer tube's contribution to the flex in the system in response to braking. After stuff has worn in (brake pads, rim, etc.) you might not need the lower housing stop position any more, but when stuff's new and picky it makes a big difference. |
#6
|
|||
|
|||
Front fork shudder / brake grab
"Anthony DeLorenzo" wrote: (Item 3) check pad angle (clip) ^^^^^^^^^^^^^^^^^^^ Not hard to check. Not hard to fix. Very likely to help. |
#7
|
|||
|
|||
Front fork shudder / brake grab
Thanks to all for the responses so far. I double-checked everything to
do with the calipers, pads, and wheel trueness. I was able to reduce the problem but not eliminate it. I did notice that the brakes are consistently grabbing at one specific section of the rim. I can't see any difference in the rim itself that would cause this. I didn't have this problem when the wheel was mounted on my mountain bike, but the stiffer fork may have just absorbed it better. I'm going to try a wheel swap tonight and see if it eliminates the problem. |
#8
|
|||
|
|||
Front fork shudder / brake grab
On Apr 9, 9:05 pm, "
wrote: Sure fix: stop the front brake housing at the bottom of the steerer tube (on the fork crown), not the top (in the headset). Redline bikes come with an aluminum bolt-on housing stop for this. This mod removes most of the steerer tube's contribution to the flex in the system in response to braking. I second this approach, assuming the simpler changes don't fix the problem. I'm a big fat guy with a 60cm Surly Long Haul Trucker and a 58cm Bianchi San Jose. The LHT has always been solid as a rock, but the SJ had terrifying fork shudder until I moved the stop down to the fork crown; now it's cured completely. I guess I am a bit surprised to hear that your CC fork suffers from this. I was actually considering replacing the SJ fork with an LHT fork at some point precisely because my LHT seems so sturdy. The CC and LHT fork specs don't look that much different. |
#9
|
|||
|
|||
Front fork shudder / brake grab
On Apr 10, 9:19 pm, wrote:
I guess I am a bit surprised to hear that your CC fork suffers from this. I was actually considering replacing the SJ fork with an LHT fork at some point precisely because my LHT seems so sturdy. The CC and LHT fork specs don't look that much different. A few factors probably contribute. I am 6'6" 250 lb., riding a 62 cm frame with a long head tube and steerer, and the linear-pull (V-brake) is a lot of brake power for a road fork. I'm more convinced that the problem is the rim. Even when I just lightly apply the brakes and turn the wheel on the bike stand, it noticeably grabs in the same spot every time. LBS has one of those Mavic rim erasers, I'm going to borrow it and see if it helps. It could just be some initial wear-in issues as well. With tinkering and riding the problem has improved, at least to the point where the front brake is now quite usable, although still annoying. |
#10
|
|||
|
|||
Front fork shudder / brake grab
On Apr 10, 9:19 pm, wrote:
I second this approach, assuming the simpler changes don't fix the problem. stopping the cable in a different spot, as suggested by a couple of people (much appreciated!): It's a linear-pull brake, so the housing runs straight from the handlebar to the brake noodle. No stops involved. Unless I'm not understanding what you propose. |
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Campy Record Front Brake Won't Fit on Fork | Kenny | Techniques | 25 | August 12th 07 04:46 PM |
converting front roller brake to front disk brake | ric | UK | 9 | July 28th 07 08:07 AM |
Front Cantilever Squeal/Shudder | monkeyboy | Techniques | 4 | July 20th 07 01:17 PM |
Tour Easy Chopper fork/26" front wheel/with Disc brake! A smooth fast ride! | [email protected] | Recumbent Biking | 1 | May 5th 07 12:03 PM |
Tour Easy Chopper fork/26" front wheel/with Disc brake! A smooth fast ride! | [email protected] | Recumbent Biking | 3 | May 4th 07 05:27 PM |