knobster

Just picked up another cross bike - Titanium Airborne Carpe Diem.

This frame has the ability to run both canti or disc brakes which is one of the main reasons I wanted this bike. (such a sweet frame. rack mounts, fender mounts and 3 water bottle mounts)

I'd like to switch it over to disc, but I'm kinda stuck on a decision.

Front wheel disc or both wheels?

I don't race cross and this bike will be used for dirt roads, trails and wet weather rides.

Wasn't sure if it'd be worth changing the rear brake since it's not used as much as the front anyways and it'd be lighter and cheaper to just do the front brake.

Thanks!

Andy_K 

I've been thinking through the process of replacing my 30+ pound winter bike with something lighter, but wanted to keep discs for the rain. I looked at frames like the Soma Double Cross DC and Salsa Vaya, but I ultimately ended up deciding to just get a disc fork for my Kona Jake and leave cantis on the back. Of course, it'll be a few months before I can tell you how happy I am with that decision.

My biggest concern is that having a rim brake in the rear will grind the rim down in wet weather. It seems like the rear wheel gets covered with about three times as much grit as the front, so I'll really need to train my brain not to use the rear brake unless I need to.

knobster

I rarely use the rear brake as it is so I don't anticipate that being a problem. Worst case is I just buy another wheel and put a disc caliper on the back. If I only do the front though, I'm probably looking at spending around $200 for the caliper and wheel.

timg7

The rear brake can be useful on rough or slippery terrain. I just started riding a bike with rim brakes, and it was a hell of a shock after years of riding with discs.

Chris_W

I switched my fork on my cyclocross bike to one that could take a disc brake about one year ago. I use the bike for all-weather training / light touring / back-road exploration, etc.

I've been very happy with the performance of the front disc (an Avid BB7), especially because of the all-weather performance, and amazing amount of braking power for a minimal amount of hand pressure. I was initially disappointed that I couldn't switch the rear brake to a disc also (the rear brake is currently an Avid SD7 V-brake, which performs well), but after riding with this setup for a year, I'm completely satisfied with only having the front disc, and have no intention to change anything else about my brake setup.

fuzz2050

You can just buy a disk compatible rear wheel, but build it with rim brake compatible rims. That way you can run rim brakes to save money and weight, or you can easily convert the rear to disc if you feel the need.

Watchdog

Do disc brakes require the lever to pull more cable than it does for cantilever brakes i.e. like V-brakes?

Do regular levers work fine with disc brakes?

joshura

Standard disc brakes require the same amount of pull as a standard V-brake, which is not the same as road style brakes or wide- or low- profile canti brakes (such as Tektro 720, Tektro Oryx, Avid Shorty, etc.)

Disc and V-brakes both require long-pull levers (Usually MTB levers)
Wide- and low- profile cantilever brakes and road brakes require short-pull levers (Usually STI style)

Andy_K 

Avid makes a road-specific version of their BB7 disc brakes that are designed for short pull levers. They work great.

darksiderising

I second the comment about the short-pull BB7s. I use them on my rugged Cannondale disc cross bike and have ridden most of the mountain bike trails, including technical and steep sections, without a moments hesitation. I have complete confidence in them.

captnfantastic

I have a disc brake capable redline. I have considered front disc only. problem is buying discs in pair is much cheaper but then again it is another
$250 at bike island for disc wheels. is a 29er mtn the same width as a road front hub? i've only had three races where discs have been a factor but i still think it would be better.

knobster

Redline has a 130mm spacing for the rear. Most (if not all) 29er wheels are going to be 135mm spacing. I think I may just build a set using the Velocity hubs.