spectastic

I'm building a cross bike that will double up as a touring bike. It will have disc brakes and a pair of bar end levers on a bullhorn handlebar. I think I will stick to the cable system, not the hydraulic system, because the mechanical system is more serviceable, and I'm not competing. one thing I'm worried about is the pull ratio of the lever on the brake pads. I've heard it's different between mtb disc brakes and cross disc brakes. I'd like to keep the cost down and get the most value. Can someone school me on the difference between mtb and cross disc brakes? I've been looking at the ebay $30 sets, which appear to work as well as any other generic sets, but recommendations would be appreciated.

Tim_Iowa

Why would you want to tour on bullhorn bars? I believe you'd like to have more than just that one far-forward riding position if you intend to spend some serious time in the saddle.

Anyway, there are two pull ratios, which dates from the advent of V-brakes. Mtb discs use that pull ratio, where some of the new road and cross discs use the old road pull ratio. They're trying to be consistent, so you can use road controls (like STI/brifters) with discs.

What kind of brakes were the bar-end brake levers designed for? V-brakes, or sidepull/cantilevers?

fietsbob

Bar end Mounted Reverse levers are Short pull so Get a Road type disc caliper .

they were Made for Side Pull and center pull brakes .. I used a set in a combination Aerobar bull, horn Time trial Bar setup ..
Cantilever Brakes ..

Though I had a (Zzipper) Fairing in front and set them up high and close for an Hour long Commute..
weight off my hands , but not bent Way Over.. for 12 miles..





'/,

spectastic

I have my personal reasons for wanting bullhorn. the only times I use the drops are when I'm tucked in on a steep descent. the corners might be a little trickier, but that's trivial. packaging the bike will also be way easier with a compact bull horn with small lever. there's also a weight incentive. it's not much, but enough to entice me. plus, I've always wanted to be cool, and this will surely make me cool

anyway, how do I tell between the road type and the mtb type disc brakes?

spectastic

also, is it wise to have a cantilever brake in the front and a disc in the rear? fingers crossed, but if dengfu is flexible, I may be able to get the fork to be caliper brake, which is easier to work with. the brake modulation will be different on each lever, but I don't think it will be a big deal. just want to run it by some people first though

Andy_K 

Only a few brakes are available in both MTB and road versions. Those are generally pretty well labeled.

IMO a cantilever in front and a disc in rear doesn't make a lot of sense. It will work, but you won't get as much benefit as you would with the disc in the front. I had a bike with a front disc and rear cantilever for a while. That was 90% as good as full disc in terms of braking performance.

spectastic

I thought cantilevers provide more braking performance. disc only adds more "feel" to the modulation. I want to avoid disc in the front because I've already got my front wheel built, and I don't feel totally comfortable putting so much strain on the spokes in my front brakes during a tour. the front wheel provides the most stopping power and therefore absorbs the most energy. I just don't want to have to replace spokes..

Andy_K 

Nearly any brake can be setup to provide as much braking power as your tire traction allows, especially in off-road situations. It's all about feel and control.

Cantilevers are an interesting brake type because they allow for a huge range of adjustment. The downside of this is that it is possible to set them up with really bad braking performance and can be very hard to get them dialed in just right. Cantilevers can be great brakes once you get them dialed in, and there are definitely reasons to use them. I've got cantilevers on my CX race bike, but part of the reason is that I frequently want less braking power than I'd get with discs.

What I'm saying is that I don't see much benefit in a rear-only disc brake. If you want to go with a canti in front, why not also use one in the rear?

flargle

I am so confused. Does the front wheel have a disc hub?

spectastic

that's what I'm saying, I've already built a wheel without the disc hub

spectastic

because I'm buildng the bike around an alfine 8 igh, which as 135 mm rear spacing, and that's a total pain in the ass to find without getting something really expensive. I've managed to find a deng fu carbon frame that will take 135, but it's a disc setup.

Andy_K 

Fair enough. There's always a reason.

Personally, I'd trust a front wheel with disc brakes much further than I'd trust a Chinese carbon frame, especially given that with disc brakes the wheel doesn't have to be quite as true to spin freely. You can lose a spoke or two and still ride it (assuming you had 32 or more spokes to begin with). Of course, it wouldn't be me having to fix your wheel in the middle of a tour.

There's a mechanic at my LBS that drives me nuts because it seems like every time I go in to ask about making some crazy idea I had work I end up talking to him and he spends more time trying to talk me out of it than helping me making it work. Most of the time my ideas end up being technically feasible, but pretty often I eventually understand why he tried to talk me out of it. I used to really dislike the guy, but now I find myself hoping he's there when I have a question. I mention this because (a) I don't want to be that guy telling you that you shouldn't want to do what you do want to do when there's no reason it won't work, but also (b) because a lot of what you want to do is well off the beaten path.

So, bullhorns on your touring bike with a disc in back and a rim brake in front? Yes, that will work.

Back to your original question... I'm not clear as to your intended brake levers. You mentioned bar end shifters, but I'm not sure how you plan to mix those with the brake levers. Do you plan to also have the brake levers at the ends of the bar? Most of the reverse levers of the type fietsbob mentioned seem to be intend for use with shifters mounted on separate aero bars. There are solutions, of course, but your choice of lever will determine the cable pull. If you plan to mount brake levers on the horizontal part of the bar, you're probably better off with levers designed for MTB brakes.

flargle

I still don't get why you built a non-disc front wheel when you knew the rear was going to be disc. But that's my problem.

My advice is: Simplify your life and use flat bars with long-pull mtb levers, and use a V-brake front and mechanical disc rear. Chop the bars as wide as you want and add Oury grips. The flat bars will be at least as useful as the bullhorns.

FrozenK

Paul Reverse brake levers will mount on bullhorns and work with either long or short pull brakes. But they are expensive. Or you can use a Travel Agent pulley.
I agree with flargle, though. I'd go with flat bars, regular regular levers and throw a set of bar ends if you want different hand positions.

spectastic

I ordered these yesterday tektro tl720 Mr Ride Tektro TL720 Aero TT Time Trial Bar End Brake Levers Silver | eBay

whats the difference b/t that and paul reverse levers? I've already got the shiifter nailed down, so no worries there.

FrozenK

The Paul lever has two pivot holes, depending which one you use it will be long (vbrake) or short (road) pull. The Tektro you bought can't be adjusted like that and is meant to be used with short pull brakes.

justin1138

alternative frame thought...

get a steel whatever with brakes you'd rather use and have the dropouts spread to fit the Alfine hub. you might even be able to find something more appropriately designed for the purposes of touring (i.e. mounting points for racks and whatnot, geometry, blah blah). you mentioned weight as one of the reasons for bullhorns, so maybe steel doesn't appeal to your sensibilities... but on a touring bike that your going to feasibly load up with stuff, is weight going to matter that much?

spectastic

Ive considered steel. but like I mentioned (soemwhere else), there seems to be a dichotomy of really expensive steel frames and really heavy vintage frames. I'm not too concerned about mounting the racks. I do light touring (20-25 lbs), which is the reason why weight is a serious consideration. weight is not the primary reason for bullhorn handlebars.

flargle

I should have added that you can find MTB thumb shifters for very reasonable price, especially if you can hang with friction, but even if you want indexing.

bikeleptic

what's really annoying is that instead of actually answering his question, everyone just criticized and told him to basically rebuild his rig from the ground up, frame and all.

Tramped across this thread because I'm basically trying to do the same thing; have a frame that I got this summer (all city nature boy) it will ONLY take disc. Just got bullhorns for it. Trying to find reverse levers that will work with disc.

As someone that tours and commutes with Scott AT-3s on multiple bikes, I see nothing wrong with your bar choice, "spectastic."

All I see is a bunch of complainers not willing to help think of creative solutions or willing to void a few warranties.

mstateglfr 

What they did is almost as annoying as complaining about the responses to a post from a year and a half ago.

fietsbob

I use Figure 8 Bend trekking bars , instead of drop bars, Now, Myself, spectastic.
then You can use regular MTB brake levers..
One Bike has MTB BB7 discs , the other Magura HS33 hydro Rim Brakes ..

On the Trekking bar, the far reach is the down , headwind posture , steep down hills And

most of the time, I'm on the back where the Brake Levers Are..




'/,

Tim_Iowa

I think everyone was boggled with the OP's reasoning for his decisions. You seem to be the first "complainer" on this thread; the rest of us were just confused.

Bullhorn bars on a touring bike seems questionable, but everyone has their own preferences.
However, the kicker was when the OP bought a Chinese carbon frame set up for disc brakes, but then wanted to run a cantilever brake on the front.
And he never revealed how he was planning on mounting the bar-end shifter and the reverse brake lever in the same spot.


@bikeleptic, you can use "regular" reverse brake levers (that have "regular" caliper/cantilever cable pull) with "road" disc brakes. For example, Avid BB7R.
Or, you can find "special" reverse brake levers (with "MTB/V-brake" cable pull) and use any MTB disc brake. For example, Avid BB7.

fietsbob

FWIW the triathlon bike segment has spawned the combination bar end brake-shifter combinations,
so as to have duplicate controls on the Aero bars , and then not have to Sit Up.

The latest , Electronic shifting, really makes this much simpler..

dabac

How often do you ever hear about broken front spokes?
The number one spoke killer is fatigue, brought on by a combo of spoke tension and load changes, both due to the rotation of the wheel and due to torque applied through the hub.
A front DB hub has less tension imbalance than rear DB hubs. And the number of times a front will see brake torque is far lower than the number of times a rear will see drive torque.
Unless you do something real crazy with how you load the bike you're worrying over nothing.