thirdin77

I'm starting to dislike my v-brakes enough that I would like to use some caliper brakes, probably these Tektro long-reach calipers. It seems my fork's recessed-style fender bolt actually could accommodate the mounting bolt for the front caliper and my bike's seatstay bridge's threaded bolt hole could accommodate the rear brake's bolt.

I'm curious as to if anyone has done this modification as it would mean faster, easier width adjustment via the barrell adjuster. As well, the flip-up quick release would mean not having to fine-tune the cable tension to enable easy release as well as adequate cable tension.

flargle

I'd be surprised if those Tektro calipers had a long enough reach.

What are you disliking about the V-brakes? And what is your lever setup? I suspect you are using short-pull levers (i.e. standard road levers) with the V-brakes. If this is indeed the case, that means the levers are not pulling enough cable for the V-brakes and, as you are finding, you have to set the pads very close to the rim in order not to bottom out the levers.

Here is your solution (and includes a barrel adjuster):

fuzz2050

If you don't like your V-brakes, get cantilevers.

dirtyphotons

i'm afraid i can't help with caliper advice, other than to say i'd measure well before buying anything. i wouldn't be surprised if long reach calipers were still too short, and they'd probably limit your tire size selection.

jagwire (as well as other companies) makes inline barrel adjusters designed to be run inline between your brake levers and the brake itself. i was having the same troubles you mention and these inline adjusters solved them all.

good luck!

TimJ

If you've got one of those tricross that came with v-brakes it came with tektro levers that are designed to work with v-brakes. So those levers would not work with caliper brakes. You'd need to replace the levers too.

thirdin77

These?



They're so cheap and look so simple to install that I may try them.

dirtyphotons

the ones you got there are designed to screw into a mount on the frame. what i was describing is something like this:



they are cheap and simple though, and i'd definitely give them a shot before trying a more expensive solution.

edit: the picture is a link, they're about ten bucks.

svtmike

The inline adjusters are designed to be run on derailleur cables. Jagwire at least does not recommend their use on brake cables.

dirtyphotons

hm, good to know. i've never had problems using them for brake cables but they do generally experience more of a load than shift cables, so it's something to consider i guess.

also i hadn't even thought about lever/brake compatibility because i assumed the bike was stock, but tricross sports usually come with cantilever (not v) brakes. it's the singlecross that comes with v's (and the appropriate lever).

i'd guess that lever/brake incompatibility is an issue here, and if so you need a pulley like the one that flargle linked to (or to switch back to regular cantilevers).

thirdin77

My Tricross Sport came with Tiagra road bike levers and V-brakes.

The Problem Solvers might be the way to go if I can leave the cable tension a bit more slack.

jonestr

everyone I know uses these on their brakes. I have never seen one fail. Even if it did fail i doubt it would break the brake cable itself as it would most likely fail along its length and not perpendicular to its length which would do nothing to the cable. Also, there is not really any compression on your housing as you are pulling cable to brake and not pushing housing. You may have some problem if you were using these with inline levers, but that would be redundant.

Other solutions are to run barrel adjusters on the housing stops at the headset and rear brake.

svtmike

I don't know the reason for it either -- but I've seen both statements that they should only be used with derailleurs and statements that mention application to derailleurs specifically, but don't address brakes. Could be the lawyers think that adjusting brakes while moving is a bad idea.

I dropped a note to Jagwire tech support to see if they can elaborate.

Leyczo

Yes, there is compression on the housing. If you dont believe me, try removing the cable housing and using your brakes. Pulling on the brake levers put the cables in tension, and the cable housing in compression, in equal magnitudes.

Honestly, though, I get the feeling the jagwires adjusters work just fine with the brakes. There is actually a fair amount of tension on the shifter cables, especially when shifting into the top gear, where the deraileur is being pushed up against the hard stops, and they are able to hold up to that. If they were to be used on brakes, and did fail, it would most likely be the threads in the adjuster that failed, and I would guess that it would just result in a slow creep of the adjustment, rather than a catastrophic loss of brakes.

jonestr

If your cable was pulling on your housing your brakes would not work so well. The only compression you get in the housing is from friction between the cable housing interface. Hopefully that is minimal. You need housing to direct your cable so that it doesent get kinked, but if I made a lever where I could run a straight line from the lever to the brake actuation. You can approximate this by just pulling on your brake cable after the housing has stopped.

flargle

I don't know why they'd sell a bike with linear pull brakes and short-pull levers. Be that as it may...I'd try the travel agents. Or, Tektro CR720 cantilevers, which are compatible with short-pull levers and work great.

dirtyphotons

^yep, sorry thirdin77 for leading this discussion down the inline barrel adjuster path. flargle's right, the problem solvers pulley should improve your braking and leave enough slack in the system for you to be able to undo the v brake easily for wheel removal.

svtmike

Those are probably the mini-V's (BMX) brakes. They are compatible with road levers. Specialized started using them on the TriCross in 2009.

Leyczo

My roomate's tricross sport came with tiagra levers and v-brakes, but it came with a set of travel agents already installed. I wonder if the shop that assembled your bike just forgot to install them.

Anyway, as you can see in the picture, the travel agents even have an adjuster built in, so they should solve all your problems in one step.


Ugh, frustrating. If you dont think your housings are in compression, cut a gap in the housing and try to use your brakes. You will notice that the gap closes up before the brakes start to move. This is because the housing is being put in compression. If you try to hold this gap open, you will notice that you are putting as much force into keeping the gap open as is being applied to the brakes.

dirtyphotons

^for cantilever brakes with a fixed cable stop the gap would close before you even apply the brake.

on a cantilever brake the housing goes from the lever (fixed relative to the bike) to a fixed cable stop. the only forces on it when you apply the brake would be friction from the cable and deformation from the cable wanting to go in a straight line, there would be no force of compression.

for caliper and v brakes, however, the housing does experience compression equal to the force of the cable pull.

so it could be argued that these inline barrel adjusters are much safer for traditional cantilevers than for v or caliper brakes.

flargle

The arms of the mini-V are slightly shorter than those of normal V-brakes. But not half as long.

The instructions that came with my Tektro mini-Vs said to use them with long-pull levers. It is possible to use them with short-pull levers, just as it is possible to use normal V-brakes with short-pull levers, but atmho the result is far from optimal, because you just can't move the brake pads far enough with a short pull lever.

And yes, brake housing works because it is under compression. That's why the ends of the housing get wedged into the cable stops and/or ferrules.

flargle

Actually, the cable "wanting to go in a straight line" is what places it under compression. That is why the ends of the cable housing get wedged into the stops.

flargle

Just to add, the fact that the housing isn't straight doesn't mean it's not under compression. Think bricks in an arch.

dirtyphotons

ok, it's enough to wedge the ends into the stops but you agree that it's nowhere near the force placed on the housing of a cable that goes into a caliper right?

flargle

No, I disagree. I don't know why it would be any different.

dirtyphotons

the difference is that with a caliper, the housing is pushing up against one of the arms of the brake. the force at the rim is transferred up through the brake arm and back to the housing, all the way back to the lever (or to the frame if there's a cable stop).

with a traditional cantilever and no inline levers, the housing stops at a fixed point and does not actually push against any part of the brake. its position is fixed at both ends. it does experience some force, but the force of the pads on the rim does not go through it directly.

it would be possible (although an awkward setup for sure) to have a cantilever brake with no housing at all. a caliper pretty much requires housing.

this is an interesting distinction to me, and worthy of a more complete mechanical explanation than i can give right now. i'll work on something more complete and see what you/others think.