I keep hearing the same reasons from racers as to why they are not switching to discs for cyclocross:
1. I have too many rim-brake wheelsets already.
2. Disc brakes are hard to set up.
3. Disc brakes have no modulation or are too strong.
I can understand the first excuse. I only owned 2 rim-brake wheelsets when I switched this spring, and my second bike was a mountain bike, so the switch according to my wheel collection was a no-brainer.
Excuse number 2 and 3 however, are false. For your rumor-dispelling pleasure, here begins a review and disc bike setup mash-up super post with a whole bunch of bike nerdery.
For those looking for the quick read, I’ll review the bike/frame as a whole first.
Like sailing seas of cheese. It’s super comfy even with road tires. I’ve almost slammed the stem since these photos because my wrists and hands have been feeling zero pain or discomfort. Butt and back only get out of whack after 60 miles, which happens to me on any bike. It scythes through grass and dirt chop on a cross course like a santoku knife, all the while putting every watt to the ground. Leg vibration feedback is also minimal while hammering through bumps.
It’s a Tarmac for the dirt. Predictable, quick, and stable. Moves over corner roughness without sacrificing traction. It’s not super-knifey because of the low bottom bracket and non-aggressive head tube angle (geo chart). But, that geometry lowers your center of gravity, and that makes for more stable cornering for those who are a bit shaky in the corners.
I can clamp on the levers and the frame handles a lockup on a downhill without a single shudder. The fork is super strong, making trail braking (dragging the brake into corners) feasible. I also believe brake modulation is increased because of the stiffness of the fork and rear triangle.
It fits 42c tires without a problem, holds 2 water bottles, it provides tons of braking power, and all day comfort. It’s only limitation is the rider. I took it on some rooty single-track, completed a 62-mile gravel race with it, and I’ll race a whole cross season on it. Few carbon race frames will beg for such treatment.
5. Ease of build
The seatpost is light and comfy, but don’t try to swap seats too often. The retention system is great for saddle rail life and adjustability, but is a pain to set up. Otherwise, you can use any seatpost that is at the popular 27.2mm diameter.
The Specialized “proprietary” OSBB system sounds complicated, but it’s not. Any PF30/BB30 crankset will fit. Or, you can use bearing cups for your Shimano or SRAM GXP crank from Wheels Manufacturing.
The cable sheaths are taped outside of the internal routing hole, making cable running a breeze. All you have to do is cut them to length when you’ve run your housing. The most of the included cable hardware is nice as well.
Conclusion: if you have the scratch and need/want a carbon cyclocross race frame, pull the trigger. It’s the best ‘cross frame I’ve ever sat on.
BB7’s with a Cleansweep G3
Disc setup guide.
Parts selection for the build were limited when I built the bike up in late February. You could go for Avid BB7 road mechanical discs, or Hayes road mechanical discs.
Since I built this bike, far too many disc brake options have become available. TRP crafted some mechanical calipers that move both pads, and an all-in-one hydraulic caliper that is pulled by cable. Sram introduced a Red full-hydro system and a 10-speed universal hydraulic lever that you can mate with an Avid hydraulic caliper.
This guide will help with mechanical disc setup.
I chose BB7 road calipers. They’re a bit heavy, but reliable and smooth operating. Even mated with old Sram Force levers with fairly short cable pull, they work great. Jagwire Ripcord compressionless housing is a must-have, along with an exceptional attention to detail when mating cables and ferrules. Making sure that your cables are cut and faced properly can make all the difference. I suggest using a grinder to face the cables, and crimping all ferrules.
Centering the calipers properly is also supremely important, to gain proper function and modulation, it needs to be done properly. To center or re-center, I loosen the caliper bolts and make sure that the stationary pad is properly adjusted so the rotor does not rub on the caliper body. Then, pull the brake lever. The caliper will automatically center itself. While squeezing the brake lever, tighten the caliper bolts to spec. After tightening, release the lever and adjust the moving pad. Fool-proof!
Pad bed-in procedure requires patience, and is worth the wait. After the pads are bedded and properly adjusted, they work very well. I used Avid HSX rotors, which helps with noise reduction and pad life in muddy conditions. The stock cleansweep rotors that come with all BB brakes are heavy, they cause squealing, and will eat pad material if there is any grit or mud in your caliper. I’m looking forward to a solid rotor to come back for improved mud performance!
Wheels and hubs are part of the equation as well. If you don’t want annoying disc rub during sprints or bike throws, make sure you have a strong hub mated to rim that is capable of high lateral stiffness. Hope hubs work very well, and I’ve tested them mated to Stan’s ZTR Crest rims, Stan’s Iron Cross rims, and H+Son Archetype rims. You get great results with any of them. Also, I’m sure any Velocity rim would work as well. I would be wary of putting any super-lightweight hubs, spokes, and rims near disc brakes.
After initial setup, carrying an avid torx tool with you is a great idea. Being able to adjust the brakes during a long ride can become necessary if you don’t keep on top of maintenance. The internal cable routing helps keep the cables fresh, so running new cables won’t be a regular practice.
Discs work great, don’t be scared. Once you get them set up, thrash them, abuse them, test them…you’ll love the results.