Monday, 24 September 2012

In the rear with the gear.....

Now for the part I like - gear.  Here's what I race on:

2011 Felt F75X.  Its a modest bike - not too out there as far as price goes, but light years ahead of that Tricross I had a year ago.  Aluminum frame, carbon fork, carbon seat stays, BB30, 105 5700.  It served me well last year with numerous wins and podiums in my categories.  But this year, I'm racing A - which means lots of fast guys.  Really, really fast.

Now will some of the stuff I've added to this bike make me faster?  Arguable....but it sure as hell won't hurt in my opinion.

The first thing I changed right away - brakes.  The factory brakes were Tektros.  They weren't horrible, but they weren't all that great either.  The worst part is that the caliper arms stuck out so far, that during a remount - twice - it caught on my leg and jammed it into the rim, lodging it between the rim and the frame.  Gladly, this only happened during warmup laps, but it made me think twice about jumping on my bike in any kind of reckless manner.

Enter Avid Shorty Ultimate

Those who race cross with any kind of seriousness know these brakes (by the way, I won't make any excuses for a dirty bike - its a cross bike - its supposed to be dirty, even after I wash it).

Fully adjustable, with the ability to tweak rebound tension, as well as pad toe-in (more on that later).  I've got them set up in the "POWER" configuration, where I sacrifice a bit of debris clearance for maximum stopping power.  You can set them up as just the opposite - lots of clearance for mud and guck, but not so much power.

I'm also using Swiss Stop brake pads, specific for carbon rims.  I haven't raced with them yet, but all I can say is the combo is nothing but very very favorable (having ridden with them on some very fast group training rides).  There is a bit of noise, but they work.

So who cares about toe-in?  Cantilever brakes are notorious for something known as "brake chatter".  Pull the front brake and the front of your bike vibrates and shakes almost to the point of loss of control. The solution?  Some say a fork mounted brake hanger - yes, helps some, but I swear by a little bit of pad toe-in.  By doing this, you induce just enough progressive modulation so that the pad doesn't grab all at once.  As a result, it doesn't induce that rapid vibration.

For more on brake chatter (or shudder):

Next, rims and tires.  Probably the most IMPORTANT piece of a cross bike is your rim/tire combo.  As with most serious racers, I run a tubular setup.  Tubular you ask?

Tubular tires have a rubber casing with tread attached, but instead of using a separate inner tube (known as a clincher setup), the tube is built into the tire and the casing is sealed around it completely - leaving the tube entirely enclosed inside the tire.  The tires are then mounted on a rim using some kind of adhesive - glue or tape - or both.

The benefits are numerous - some of them being

1)  The tube has no chance of being pinched between the rim and the tire - a common cause for flats with a clincher setup.
2)  The tire does not need reinforced sidewalls to withstand the forces and pressures of clinching onto the rim.  This allows much more supple materials, which leads for a much softer, compliant ride.
3)  Because of the 2 above points, you can run much much lower air pressures, since there's no risk of pinching or tire sidewall failure - low pressure = better traction and rolling resistance over rough terrain.
4)  Because the rims don't need extra strength to hold onto a clincher tire, they are much lighter.
5)  Small punctures due to debris are a non-issue if you use sealant.

This illustrates the difference in shapes between a tubular rim and a clincher rim

The black represents the tire mounted on the gray "aero" rim.  The rim on the left is a tubular rim.  The tire sits more or less on top, with strength coming from the adhesive.

The centre and right show a clincher.  Notice the extra material required in the rim to hold onto the tire, and notice how the tire must have strength and rigidity built into it to clamp into the bead of the rim.  This contributes to the harsher ride associated with a clincher.  Now also picture an inner-tube lodged in there - any deformation of the tire sidewall can lead to a potential "pinch flat", there the tube gets pinched in that clamping area between the tire and rim.

What about the "bads" of a tubular?

1)  Tires are expensive.  They tend to be hand made, using more exotic materials.  A good tubular tire costs upwards of $100 to $120 - with premium ones reaching $200.  A clincher tire hovers around the $50-$75.
2)  The mounting process can be cumbersome and time consuming.  Depending on the method, it can take up to 2 days to mount a tire.  A clincher?  1-2 minutes.
3)  Poor adhesion can lead to failure.  The tire can roll off the rim if the glue or tape fails.  This can be a show stopper.
4)  Its difficult to change tires to suit the conditions of the course.  Once a tire is mounted, its on there for good - unless the glue fails or you literally tear off the tire.  Tubular fans typically have multiple rims with different tires to suit the conditions of the day ($$$$$).
5)  Similar to #4, if the sealant does not do its job and you get a flat, you can't exactly change the tire in a jiffy.  Back-up wheels with tires are a must in the pits.

So what am I running?

My race wheelset is a set of Boyd Cycling 38mm carbon tubular rims.  They are 23mm wide, as opposed to the standard 19mm wide road wheel.  This offers a wider gluing surface for the tires and helps the tire conform to the surface.  Boyd Johnson is a builder out of the USA.  He runs a stand up company and my experience with him was awesome.  Very high quality carbon rim, Bitex hubs and Sapim CX Ray aero spokes.  Check him out at 

For tires, 34mm Vittoria Cross EVO XG.  Similar to the Challenge Grifo, its a fast tread with decent all round grip.  Its a jack of all trade tire, but not an expert at one type of course.  Its a good tire for someone (like me), who can only afford 1 set of tires.

My backup set:  the factory Felt clincher cross rims with 33mm Clement Crusade PDX tires.  I have nothing but good things to say about the PDX's.  They roll fast, and have super grip in high speed corners.  I have yet to shake them out in a race, but I have a good feeling about them (knock on wood). That said, they may never see a race if my tubular setup stays reliable.

One more thing - Crank Bros Eggbeater pedals - the best mud shedding pedals out there - love em.  I ditched my Shimano M520 pedals after 1 race.  I just could not clip in after any contact with mud or dirt.  The Eggbeaters have been flawless.

Up next, gluing tubulars....

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