ducati

I just wanted to post a quick note to the 'cross folks. I have an '06 Poprad w/cantis and the alu fork. I have been dealing with the extreme fork chatter that can sometimes actually brake the front wheel loose; apparently this is a common issue with these bikes, as another local fella (who is a 'cross racer, I am not) was complaining about the same thing.

After trying pad angle adjustments, and passing on switching pad compounds, both recommended fixes from LeMond, my shop told me to email LeMond customer service. I did so, merely asking if this was an inevitable consequence of a design decision, or something that could be prevented with some tweaking. I received an almost immediate reply that the customer service rep wanted to talk to my shop.

They sent some carbon replacement forks to my shop, and now myself (and the other local 'cross racer) are running on carbon forks.

I haven't ridden the Poprad a ton lately, preferring my fixed gear bike, but in the few rides since the fork replacement I can say the chattering seems to be reduced nicely. The bike feels much better now. Still a little chatter when hard on the F brake at low speeds, but I've always felt this on canti bikes. Nothing that feels like it will force a spill.

So if you have a Poprad with the alu fork and cantis, you may be able to get switched out to the carbon version for free. I thought this might be of interest to some folks, hope it helps someone out there.

trirod

That's good to know - I have the same issue with my '05 Poprad so it might be worth my while emailing them too.

One thing that helped quite a lot was replacing the stock Bontrager wheels with Mavic Open Pros. I think the Mavics are more solid (they certainly have a lot more spokes) and they decreased the chattering to a tolerable level. Of course having to spend $200 on new wheels is not a good solution when you've just spent $1300 on a brand new bike.

i_r_beej

This is really weird.

I've read many posts here about brake chatter on CX bikes-- including, but not limited to LeMond Poprads.

I have an '06 Poprad (orange) and i DID experience horrible chatter with the stock Avid brake pads. I switched the Avid pads out for Kool-Stop dual compound "Mtn. Pads" which dramatically reduced brake chatter. After two races with plenty of fast descending i have yet to experience any noticable chatter.

What kind of carbon forks did you get? They had canti studs? I'm not aware of any Bontrager carbon CX forks with canti studs.

remoran

What was the email for LeMond Customer Service?

ducati

The chatter I got, i r beej, was like an uncontrolled oscillation in the fork, and it VIOLENTLY chattered to the point the front tire would lose traction with the surface of the road. You had best catch your fall with your foot, then, or you're going down. Kindof a downer on my commute.

It's hard to catalog in my head when that happened what the conditions were, but I do recall one particular hill where it happened towards the bottom multiple times. I believe, for me, it occurred after very heavy braking on very steep hills, towards the bottom of the hill. So not FAST descending, per se, more after a fast and heavy braking episode.

The gentleman who runs my local LeMond shop is a motorcycle racer (going AMA 600cc next year!) and he believes that the aluminum fork could vibrate unsympathetically with the steel frame, exacerbating/causing an oscillation of sorts. He believed, and was correct, that a carbon fork would dampen the oscillation or perhaps not setup the oscillation. I do not know if he convinced LeMond to try this, I believe it was LeMond's own idea.

The carbon fork is a Bontrager "Satellite Plus" I believe. Yes, it has canti studs. It also has fender eyelets, which I was pleased with.

I found the email for LeMond customer service off their website, as I recall, you had to fill out an online form.

Hope that helps.

ducati

This weekend I noticed the Satellite Plus fork on a Trek X02 at a local bike shop. Here's Trek's stock photo:

noisebeam

What is the take on using these specific replacement forks on rough terrain? Can they take the abuse that the original aluminum forks could? If not what is the limit they can take?

Al

i_r_beej

Funny-- that XO and the canti Poprad are about identically spec'd (except for the frame, of course). I know-- Trek owns just about every bike brand out there.

Anyway-- about the longevity and reliability of carbon forks. Manufacturers wouldn't be making them, and offering such long-lived warranties, if they couldn't take the use that they were designed for.

That said-- their only "weakness" is susceptibility to surface damage. If you have a crash inspect your carbon stuff immediately. Any deep scratches-- something that a fingernail can get caught in-- can cause the part to snap along that scratch. It's a bit like a perforation in paper. And snap they do-- there's typically no warning. Carbon composites don't bend or deform prior to failing like most metal alloys will.

Still-- every Sunday at the 'cross races i see at least as many carbon forks as i do steel and aluminum.

noisebeam

Thanks. Just curious how it would hold up on a fairly rough singletrack trail. I no longer ride this type of trail with the Poprad, but do very often ride 4WD roads (aka fire trails) and one inevitably comes across a significant bump crossing a wash or other water damage in road.

Is this CF fork more durable than those found on a performance road bike because of its intended use?

Or are CF forks as strong and durable as steel/aluminum forks as long as they don't get non shock/vibration damage (i.e. scratches, cuts)

Al

darkmother

The thing that makes me nervous is the possiblity that a crash could cause invisible, but sigificant damage to the fork. Recently, I crashed my CX bike really hard riding some singletrack, and I bent the Kinesis fork that I had on the bike. The damage was really obvious, so I replaced the fork. However, what if I had had the same crash on a carbon fork? It might have snapped, which would have been fine (except that I would have had to walk home). But what if it didn't snap, but was damaged? The alignment of the fork would not change, and there might not be any visual cues that something was wrong. I could end up riding around on a time bomb.

That said, you don't see a lot of carbon forks spontaneously blowing up. They seem to be quite reliable.

noisebeam

This is interesting discussion.

I wonder if LBS/Trek is going to let me keep the original fork, or if it will need to be sent back as some (generally broken part) warrantees require? Hopefully I can keep the origninal aluminum fork to use as a temporary stop gap replacement if I ever notice or think the CF one got damaged.

Al

Cyclist01012

IS the fork a replacemant for warranty claim? If so yes they will generally keep the fork. If you are buying a different fork no the old fork is yours

i_r_beej

Yes-- the carbon CX forks are not just road forks with canti studs laid in during manufacturing. They are more "built up" and thus stronger.

A carbon component, when the same weight as metal component will be many times stronger. A carbon component just as strong as a metal component will be significantly lighter. Most carbon composite components fall somewhere in the middle-- stronger than metal alloys and quite a bit lighter.

One final problem that i have with current carbon composite components is that there is an industry shortage. Carbon is in high demand for airplanes (Boeing alone uses more carbon than the entire bicycle industry) and other "industrial" applications.
A common technique is to combine carbon with other composite materials-- NOT carbon fiber-- to create something that looks like carbon fiber on the outside but ismade with weaker materials on the inside (like fiber glass). The killer is that it is virtually IMPOSSIBLE to tell in the final product without actually destroying it and carefully analyzing it. So this is kind of an issue within the bicycle industry-- "Is it really really 100% carbon fiber??" Only the manufacturer can tell and they're keeping it a secret. Besides which-- auditing manufacturers is extremely difficult.

noisebeam

And can I assume this Satellite Plus fork lemond/trek is providing as a replacement is a designed for CX 'stronger' fork?

I assume as its on the Trek X02, but I wonder because of this:
https://www.bontrager.com/Road/Components/Forks/5808.php

Al

i_r_beej

Bontrager.com's site must be a little out of date? (That's why i questioned the original poster about the carbon fork-- i was only aware of the Satellite Elite and that fork only has disc mounts.) The Trek product page for the XO-2 indicates that the fork is a "Bontager Satellite Plus, carbon".

Note that the fork shown at the link you provided doesn't have cantilever bosses. The fact that a fork HAS canti bosses hints that it isn't for "regular" road-racing use and is intended for something a bit more robust.

So i'd suggest that you check with your local Trek dealer.

danimal

okay, so i stumbled on this thread as i was searching for others with a problem with thier poprad....i have an 06 and the chatter i'm experiencing seems on the level with ducati's. -so i emailed lemond last week (friday) and still haven't heard back. if i don't hear back, any thoughts on what i should do? i bought my bike in phx but have since moved to new mexico....any thoughts?

noisebeam

Just wanted to add links to my posts from past where I commented on the shudder problem:

June-2006:
https://www.bikeforums.net/showpost.p...01&postcount=5
https://www.bikeforums.net/showpost.p...6&postcount=11
July-2005:
https://www.bikeforums.net/showpost.p...7&postcount=16
June-2005:
https://www.bikeforums.net/showpost.p...00&postcount=2

As you can see its been a problem on my Poprad for a while now. It got to the point that I found it so dangerous that I don't ride it anymore - hopefully a new fork will fix this.

Al

i_r_beej

This seems to be an issue that many riding 'cross bikes are experiencing.

Here's my take on it:
I race weekly. After my race is done i stick around and watch some racing. On a recent race there was a long fast DH section. I decided to really watch the bikes as they came down the hill and decelerated just before a turn and saw LOTS of fork "oscillation". It was quite noticable from even 50 feet away!

I attribute this phenomenom to a few factors. Back in the cantilever brake's heyday (80's and early 90's) mountain bikes were relatively "overbuilt" and had less of a problem with front-end brake chatter-- but it still existed. (I could watch my Tange Switchblades deform noticeably during hard braking.) Modern lightweight 'cross frames are less "immune" to the effects of hard braking and only exacerbate the problem.

I think the right combo of carbon forks (which tends to absorb any resonation rather than transmit or amplify like metal alloys), linear-pull brakes, and good brake pads will greatly reduce the ocurrence of brake chatter.

NYCBM

It seems lemond's cross fork suck. I have the 06 disc fork and it has extreme flex. My other steel fork is stiffer then this crap.

hamr22

I don't want to start a firestorm here, but the bontrager cross forks look to be about 8 ounces lighter than a steel cross fork, or a third of a 24 ounce water bottle, which is essentially one big swig of gatorade. Is this "lightness" worth the chances that it will detonate on you after it is scratched?

scotton

I have never experienced brake chatter on my 06 Pop. My only logical solution is that you need to gain 50-75 pounds and not go as fast. Works for me.

danimal

so i got a reply from lemond: they say to "get a harder-compound brake pad and toe-in the brakes...if problem persists take it to my local lemond dealer." -thanks a pantload, lemond. anybody try this? if new pads don't work i may as well keep hassling lemond in hopes of a new fork