![]() |
| Tire Lever Shrapnel |
Monday, April 9, 2012
Reasons I’m Not a Doc: Sponge Left in Body
Tuesday, January 17, 2012
#Cyclocross Sizing Tires Like Carry-on Bags
![]() |
| A 33cm Clement PDX Clincher Too Fat for UCI |
![]() |
| Rider: "We Can't Hear Back Here." UCI Official: "Listen!" |
![]() |
| A Nice Addition to Your Toolbox |
Monday, October 10, 2011
#OVCX Gun Club: This Is What CX Is About
I’m curled up in a fetal position clutching my Simon
Burney book “Cyclocross – Training and Technique.” I used to think cross was a balancing act
between our checkbook and a functioning bike, IPA and body weight, hill repeats
and a healthy marriage, core workouts and clean dishes, recovery rides and a
well kept lawn. I’m realizing cyclocross
is more of a 60-40 or 75-25 than a perfect 50-50 balance approved with a gas-pump
type sticker autographed by Dusty Rhodes, our Hamilton County Auditor. ![]() |
| My Best CX Season p/b Pearl Izumi |
![]() |
| Having the Best Race of the Season-my balls not so much |
Thursday, April 21, 2011
Sitting In and 2 Other Ways to Be Mediocre & Survive
Friday, March 11, 2011
Anatomy of a Death Rig
Reader Jason was brave enough to post the photo of his Sub 9 Death March Death Rig to The Best Bike Blog EVER's Facebook page. He was the only one. The Death March causes cyclists to evaluate everything. Jason's running a seatbag big enough to carry a bible and a wooden stake in case of a zombie encounter at one of the cemetery checkpoints. Personally, thinking maximum power on the roads and minimal time in singletrack, I even considered road pedals. The test ride was unsuccessful, road pedals are not a good idea if you have to walk more than 3 steps in the mud or run from a pack of zombies and/or vampires. Like Jason, I opted for the happy medium of Candy SL's, a platform for the road and good mud clearing. Most readers were afraid of sharing team secrets or having their fragile cycling ego's crushed by the scrutiny of bloggers with a paint program and way too much time on their hands. Jason, we commend you. Now prepare for the scrutiny.Jason, like over 150 others spent the last week matching his bike to the exact percentages of gravel, pavement, dirt road and singletrack their team plans to encounter. Judging by the Jet Race file-treadish rear tire and knobby front, we figure Jason is making the most of the gravel roads and minimizing muddy uphill singletrack exposure. Others planning to ride mountain bikes, will no doubt try to take advantage of the singletrack shortcuts between check points. I will say it right now, we will likely see a road bike with 28c file treads barely clearing the fork crown and seatstays.
Right at this minute, Jason is reconsidering his rear tire choice, as noted by the extra wheel. He may also want to take care of that mis-matched red cable housing near the rear derailluer tainting his otherwise pristine Death Rig or it will drive him nuts for 4-5 hours on Saturday. Yeah, that was the first thing we noticed.
Good luck y'all. For details and to register click here for the Sub 9 Death March Website.
Monday, December 20, 2010
Gift Cards b/c I Love You, But Not That Much
Tuesday, August 4, 2009
Cyclocross Carbon Fork Brake Shudder: I’m No Engineer But I Think I Have This Figured Out

I inadvertently performed a bike experiment last night after work. I took my cyclocross bike, an Indy Fab Planet X with an Easton EC90x carbon fork for a spin at a nearby park. Since the glue job on the Zipp 404 CX tubulars was fairly new, over the past week I kept the air pressure high to make sure the glue cured and stuck to riding the roads and bike path while I dialed in the fit. Yesterday was my first cyclocross style ride with the tires at cross pressures. Instead of driving the mile to the park, I decided I’d just let some air out of the tires in the parking lot at work and ride over to the park. I guessed at it and let air out until I could squish the Vittoria file tread really good with my thumb. The ride in the park for the most part was fine, although the pressure was probably a tish too low on the hard ground. The bike felt like it was pushing to the outside in corners (as if the tire was sort of rolling under the rim.) Since my pump was a mile away, I just dialed back the cornering speed and went on with my ride. Coming down the steep road back to my car at work, I hit the brakes, and I felt the familiar tug-tug-tug of brake shudder. I could see the ends of the fork blade move. Son of a!
I had been riding this bike for at least a week and a half with the tires over 60 psi with no brake shudder. Now the tires were at the extreme opposite (guessing around 28-30-remember I let air out without a guage), probably a few PSI too low for hardpack causing a little shudder when slowing at the bottom of a paved hill. I knew about the possibility of brake shudder with carbon cyclocross forks and consequently hung on to my trusty steel fork in case this was to happen. However, I hardly think it’s time to ditch the carbon fork. You have to admit, it’s pretty rare to have a paved descent in a CX race. I didn't feel a single bit of shudder or snap while riding in the park and I even bombed a few grassy downhills where I had to brake into a corner.
It was a long hill; long enough to hit the brakes and watch what was happening. The brakes were slowing the wheel, but the tire was spinning just a bit faster. When I hit the brakes, the tires traveled a little further than the rim, causing the sidewall of the tire to give a bit and in reaction, causing the fork to flex under the bike with the grabby pressure. Ah ha!

Of course, putting the steel fork back on would reduce the shudder. But, I don’t think the problem is severe enough to add a pound back to the bike. I also think brake shudder isn’t the correct description. It’s more like fork snap. I think Carbon forks are stiffer and snappier. We all know steel has a very soft and easy flex to it. I think the steel fork flexed too, but it never snapped back to shape as quickly as the carbon. It’s like the difference between bamboo and pine. Both forks will flex under braking pressure. It’s just that the carbon fork will snap back into shape while the steel fork will flex, stay in the flexed position longer and go back to it’s original shape more slowly and less noticeably when the pressure if relieved. In addition the IF steel fork has a greater degree of rake, (48mm compared to the carbon’s 45mm). From the beginning the steel fork puts the contact area of the tire more forward than that of the Easton EC90x.
You can do a few things to minimize the “snap.” The usual fix is to try toeing in the brakes which will put less initial brake pad in contact with the rim surface, which I assume reduces initial braking power, makes braking more linear or gradual, and consequently reduce the fork flex at the other end. However, I think that’s only half, or more likely a quarter of the solution. I think tire construction, the grippiness of brake pads, tire pressure, fork rake and even the hardness of the ground play an equal role. I would go even as far to assume a tubular with a soft cotton sidewall and latex inner tube (like a Challenge or Dugast), would cause more carbon fork snap than say a Tufo or Vittoria with a thicker sidewall and standard rubber inner tube. The ground was hard yesterday, I really only needed to run low enough pressure for comfort and keep the tires from rolling in the corners. I think a few more PSI would’ve made all the difference. The other thing to note is that I didn’t feel any fork snap during the CX practice. It didn’t snap until bombing down a long paved hill.
I think the trick is to keep enough air in the tires so that they hold their shape in the given conditions. This optimal pressure will change with the course and conditions. If the tires hold their shape, that’ll give the contact patch of the tire less opportunity to get under the fork and pull it backwards. The fork snap should be reduced. Air is the least expensive of the possible combination of solutions.
Ahh. Fhew. Time to put on my smoking jacket and ease into my high-backed leather chair with a snifter of brandy.
















