Cyclocross - insane stutter, Easton EC90, fork deflection, death
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09-23-09, 06:38 PM
I just mounted an cross EC90 fork, FSA headset, and Cane Creek canti's with tons of toe in and soft shoes on my Raleigh (basically Kenisis cross frame).
At ten miles per hour, the application of the front brakes creates an insane stutter, fork deflection of several inches, and the feeling that certain death would accompany the application of the front brakes in normal riding.
I put 5 different people on the bike from the welter weight 150 LBS wrench to by 285 pant load and everybody had the same, "woa dude" experience of certain death.
What the heck is going on. Is the EC90 just so flexy that only sub 60 pound riders need apply or have a I missed something. I have never, ever, seen anything like it. It makes me think I need an all steel trials fork for my cyclocross bike.
I had the same problem with my EC90x and Raleigh RX1.
Heel in the pads like crazy. Like a really good amount, and it should stop the shudder.
09-23-09, 08:26 PM
Funny, I have no problems with mine at all. Mine is attached to a Cannondale CX9 and I'm using tektro 720 calipers on it.
09-23-09, 09:57 PM
I would try getting a straddle cable and yoke and varying the height of the yoke above the tire and see what happens
I am running the same fork, and I tried those brakes (went back to shorty 4s), with the bottom of the yoke 1.5" from the tire and maybe 2mm of toe in (folded piece of paper)
No shudder at all, but I am running a different frame
09-24-09, 09:12 AM
I have a RX-1 with the EC90x fork, LX Deore brakes with Kool Stop pads. I have a pretty good amount of brake pad toe in and have no shudder. My Kool Stops have a mud sweeper that forces you to toe in the pads.
With my worn Ritchly (sp?) pads I was starting to get some shudder, due to the amount of wear I just replaced them rather then trying to adjust them.
I'd try new pads and more toe in like already stated.
edit: it should be heel the pads I guess. I'm an auto technician and it "looks like" toe in to me
Maybe try a brake booster/bridge and see if that helps.
09-24-09, 09:25 AM
Also, keep in mind that as your pad wears you will lose your toe-in.
09-24-09, 09:43 AM
The shudder comes from the long distance between the brake hanger and the brakes. Try to jimmy a hanger that fits right above the fork--it can be done, and I think you can buy one now. Think of the old mountain forks--they did the same thing.
tons of toe in and soft shoes on my Raleigh
From my perspective, this is probably the problem. Jawn P says to try setting the pads "heel in". My thinking is that harder brake pads are likely to help - they are less "sticky" and the force between pad and rim is stronger whenever you brake hard. (when the force between pad and rim is stronger, there should be more resistance to 'bouncing' motion or vibration). I also think that having your pads set with lots of "toe in" is problematic, and that you'll get less shudder if you try lots of heel in, a little heel in, or a little toe in. (see what seems to work best for you.)
The shudder comes from the long distance between the brake hanger and the brakes. Try to jimmy a hanger that fits right above the fork
With cantilever brakes, I don't think this is where the problem lies.
09-24-09, 03:20 PM
BRUCE!!!!!! This is Chris from the shop...
What he is saying is spot on, We have tried all levels of toe in, out, flat, different pads, everything. Have you tried the brake booster yet? Also if you have them try some v-brakes and that might save you from buying that new fork.
09-28-09, 08:43 AM
With cantilever brakes, I don't think this is where the problem lies.[/QUOTE]
Actually, I'm quite sure this is where it lies, as I have dealt with this a few times. Old mountain bikes used canti brakes, and they had a cable hanger built into the fork--suspension forks used to have these. When everyone switched to V-brakes, they disappeared. The problem is the long run of cable from the stack down the head tube to the straddle. Trust me on this one. Install a cable hanger down there somewhere and you will have shudder free love with the flimsiest of carbon forks.
Maybe try a brake booster/bridge and see if that helps.
I used to use one of those around the time shocks first came out. The shocks back then had a number of limitations. It definitely helped.
09-28-09, 11:04 AM
regardless of pad alignment, my front hub has been slightly loose before and caused shuddering. have you checked it?
fwiw, i run avid v brakes on my mountain bike and recently starting running brake boosters. it has made a huge improvement in my braking. i can one finger most things now.
09-28-09, 01:11 PM
"Actually, I'm quite sure this is where it lies, as I have dealt with this a few times. Old mountain bikes used canti brakes, and they had a cable hanger built into the fork--suspension forks used to have these. When everyone switched to V-brakes, they disappeared. The problem is the long run of cable from the stack down the head tube to the straddle. Trust me on this one. Install a cable hanger down there somewhere and you will have shudder free love with the flimsiest of carbon forks."
This is exactly it, as an experiment and I could stop my fork from shuddering by simply putting pressure on the cable with my finger when braking. It's also the reason Specialized is now using a hanger bolted to the fork on the 2010 tricross. I eventually went to Mini-v's...way better.
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