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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 11-12-07, 01:37 PM   #1
fender1
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2006 Lemond Poprad: Fork Problem??

Hi. I am looking at a lightly used 2006 lemond Poprad with Canti brakes and the alloy forks. I vaguely remember reading that there was a problem with the handling of the bike due to a problem of some sort with the alloy fork. The search function here turned up nothing. Am I remembering this right? Anyone else remember this/ experience this?
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Old 11-12-07, 01:45 PM   #2
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The fork is aluminum and many people experience fork chatter when using the front brake. One solution is to abandon the cantilever brakes for mini-V brakes (but there are other issues with that approach). Another solution is to use a fork-mounted cable stop such as this: http://www.sheldonbrown.com/harris/i...tektro1257.jpg. Others have argued that the chattering can be fixed by using better brake pads and having proper toe-in. In my experience (2006 Poprad with alunimun fork), toe-in adjustments on the stock Avid cantilever brakes made little-to-no difference in the amount of fork chatter.
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Old 11-12-07, 02:14 PM   #3
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The fork is aluminum and many people experience fork chatter when using the front brake. One solution is to abandon the cantilever brakes for mini-V brakes (but there are other issues with that approach). Another solution is to use a fork-mounted cable stop such as this: http://www.sheldonbrown.com/harris/i...tektro1257.jpg. Others have argued that the chattering can be fixed by using better brake pads and having proper toe-in. In my experience (2006 Poprad with alunimun fork), toe-in adjustments on the stock Avid cantilever brakes made little-to-no difference in the amount of fork chatter.
Thanks. Any idea if a change in brakes (From avid shorty to tektro Oryx) would make a difference? I could also use a set of salmon kool stops.
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Old 11-12-07, 02:45 PM   #4
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Thanks. Any idea if a change in brakes (From avid shorty to tektro Oryx) would make a difference? I could also use a set of salmon kool stops.
In my experience the tektros modulate a little better than the avids (have a bike with each setup) but are also a bit less powerful. Once I put Kool stops on the Tektros they have been both powerful and well modulated. Hopefully a pad change on the avids will do the same. I should note though that the avids aren't bad by any means.

On the othe rhand there are many factors besides the brakes themselves. I have the Oryx's on a steel touring bike with a relatively flexy fork and lots of rake. The Avids are on a carbon fork without nearly as much rake. On the oryxs I have one of those cable hangers that goes onto the steerer tube under the stem/spacers, on the bike with the avids I have one of the fork mounted deals pictured above. I say get the bike and don't worry about chatter. If it is a problem, replace the pads with kool stops. This isn't an issue that needs to be super expensive, if it is an issue at all.
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Old 11-13-07, 09:59 AM   #5
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Ok and thanks for the repiles. I am going to check out the bike hopefully tomorrow. If it is in as nice shape as the seller states, (said he rode it around the city a few times, never raced) is it worth $600?
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Old 11-13-07, 01:27 PM   #6
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I have an '06 Poprad. All the problems described are TYPICAL of cantilever brakes. I grew up riding MTB's when cantilever brakes were the only option.

Proper set-up was always fussy. There were a slew of products and cantilever designs aimed at solving set-up hassles.

For the Poprad, the stock Avid brake pads are horrible. I switched to Kool-Stop's dual compound "Mtn. Pads" and that one thing eliminated 90-percent of the front brake squeal and vibration. I have also used Kool-Stop's Eagle II's to great effect.

You will, however, experience front-end vibration to some degree no matter the brakes you use. That's just something inherent in the design of the system.
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Old 11-13-07, 06:49 PM   #7
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IMHO $600 is a great deal for an '06 Poprad if it's in good shape. You might want to take a look inside the seat tube and see how much rust it has. If the frame hasn't been treated with Frame Saver or something similar, you'll probably want to do that if you get the bike.

Last edited by fatchance; 11-13-07 at 09:06 PM.
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Old 11-13-07, 06:54 PM   #8
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I have an '06 Poprad. All the problems described are TYPICAL of cantilever brakes. I grew up riding MTB's when cantilever brakes were the only option.
I have ridden a whole lot of mountain bikes with cantilever brakes since 1985. In fact, all of my current MTBs still have cantilever brakes. But I have never experienced fork chatter like I did on the Poprad. It was pretty extreme. I did not try swapping out the brake pads, however.
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Old 11-13-07, 08:37 PM   #9
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That is a great price on a clean '06 Poprad. On my cx bike I had horrible front end vibration and noise ('07 Kona JTS) until I finally got the toe in right on the pads. Bought the cool stops but never put them on.

Bill J.
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Old 11-15-07, 01:41 PM   #10
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The 06 fork is a design flaw for sure.
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Old 11-16-07, 02:40 PM   #11
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Here are videos of me riding a 2006 Poprad with salmon kool-stop pads, a properly tightened headset, as best as possible adjusted brakes with probably a half dozen different attempts by experienced and qualified techs to eliminate squeal or shudder. I found that with adjustment one could reduce shudder (dangerous) or increase in squeal (annoying). I choose to bias the adjustment to the squeal side after some harry stopping experiences with shudder causing the front wheel to actually skip on pavement.

I developed the habit of using less front brake over rear brake to avoid the squeal, which is why you don't hear that much in the videos. That is not a good habit to have.

http://www.youtube.com/watch?v=nGuZOpEou1s, a burst of squeal
http://www.youtube.com/watch?v=aYudFGGsit4, some bursts of squeal near end, using rear brake mostly
http://www.youtube.com/watch?v=kkikKJ28SJU, just a small chirp of squeal, mostly rear brake use

I found the shudder (for road use, no CX) to be a safety issue and wrote a letter to to Lemond who promptly provided at no charge a replacement carbon fork (thru LBS). This fork eliminated the shudder and greatly reduced the squeal, an improvement, but not perfect.

The problem is also much worse on pavement with road tires vs. trails, grass, dirt, etc.

Al
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Old 11-18-07, 10:18 PM   #12
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Noisebeam -- Which carbon fork did they send you?
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Old 11-19-07, 08:45 AM   #13
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Noisebeam -- Which carbon fork did they send you?
It's a Bontrager Satellite Plus with canti studs and fender eyelets.

Al
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Old 11-19-07, 10:41 AM   #14
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Thanks for the video. I took the bike for test run on Saturday and decided not to buy it. It felt a bit cramped (57cm) and the squeal/shudder was substantial. It had 32mm road tires on it and had the stock brakes pads etc. Since I am not racing and the bike would serve more as a commuter, with the potential to do some racing next season, I am going to stick with the 2007 SOMA Double Cross (59cm) I picked up recently. I got it w/ Ultegra and a Cross Check fork for $600 as well. I am running it as 1X9 W/ A 42TH chainring.
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