MrEaves

I have a new cyclocross bike which I use every day for commuting. The traffic can sometimes be quite hairy so I was thinking of retro-fitting a mechanical front disc brake (Avid BB 7 road seems to be the way to go). I will leave the back as is.

The fork doesn’t have disc drop outs and the hub does not have rotor mounts. So at the very least I need a new fork, and a new hub. I am hoping that the hub can just replace the one I have so I can keep the rim and spokes and just have the wheel rebuilt.

This all should mean I can keep the 105 STI shifters and set up as is as the brakes are mechanical, and I have seen a similar setup on a La-Salas cyclcocross.

Anyone got any tips for this, pitfalls, recommendations for parts, etc, etc. The Avid BB 7 is £45 for calliper and rotor, I don’t want to spend much more than £30 - £40 on a hub, and £70 - £90 on a fork.

I will be getting all this fitted at a bike shop so it is done properly.

Any help is much appreciated.

Aeroplane

You might want to just get a new front wheel, that way you'll be able to go back to your normal setup if you don't like it.

stevage

I recently did this on a Tricross Sport that had a collision. New wheel (cheapie), new fork (specialized sirrus carbon/alu), brake (err, something "road bike" ish). Dunno whether it was the LBS's shoddy workmanship, but it's been very fiddly getting the brake pads set right. Haven't yet got the performance better than the canti it replaced. Also, I'd triple check that the brake cable travel on the brake you're considering is compatible with the levers.

(Lastly, are you absolutely sure that a cable pull disk brake is much better than the caliper or whatever you're using now?)

dwr1961

I think running a disc up front and keeping a rim brake in the rear is reasonable. I can recall several MTB's from the late 90's that had that set-up when discs were new and expensive technology. Most of your braking power will come from the front brake anyway, and a road disc is more powerful than any other brake out there.

I recommend the Avid BB-7 road disc brake for your project. It is linear, powerful, and very easy to set up and adjust. It works with brifters or aero levers and has an in-line cable adjuster for fine tuning. I have a set of these on my CX bike and love them - both for their stopping power / modulation and their ability to handle rain, snow and mud with no loss in performance.

I also suggest that you buy a complete front wheel with a disc hub unless money is really an issue. A "29'er" wheel will work - and might be the easiest way to find an inexpensive disc-compatible 700c option. The only drawback would be that the rims are wider and aren't really made for a tire less than 28c in width (people ignore that guideline all the time and mount skinnier rubber, but it might be a safety issue).

I saw road BB-7's this morning at Bike Nashbar for $64 each...

Hope this helps.

Raiden

I'd also ike to chime in, in support of the BB-7. I like the adjustability over the BB-5s, and they work just fine in comparison to equally-priced hydraulics.

I like the idea of just buying a new front wheel. I'll bet you can find a complete disc-compatable wheel online for cheaper than a shop can build it with your old hoop.

Also, risking sounding like a shill, I have a fork suggestion: https://cotic.co.uk/order/forks/ Cotic's Roadhog fork. It has mounts for disc calipers, canti/V-brakes, and road calipers and fenders for 60gbp.

MrEaves

Thanks for all the replies guys, much appreciated. Definitely BB7’s as I have read a lot of good reviews.

I am pretty sure the mechanical disc would be better than my linear pull brakes, I have had mechanical discs before and they were much better. I’d love hydraulic discs as the ones are my mountain bike and my hybrid are amazing, but I am afraid that is out of the question as they won’t work with the 105 brifters.

I’ll look into the full wheel set up, but I was looking to save a few pounds, but also to make sure the front matched the back, it is a Colnago Worldcup cyclocross so I didn’t want to deviate too much. On the other hand though I suppose selling a full wheel may get me a few quid more.

As for a 29 inch wheel, won’t that raise the bike a little, or not be balance with the back 700c ? Or I am not thinking straight?

MrEaves

And those forks look good, I want black to match what I have now.

Raiden

29er and 700c are the same rim diameter. 29er/cyclocross tires are going to be taller, though.