Bicycle Mechanics - HELP! broke the V Brake boss off my frame

ok so while i was doing some winter tune ups, i was tightening my v brakes down after replacing the brake line and lubing the joints, i tightened down the brake and it just snapped, ive had issues with this brake since i aquired the frame, hence why i was tuning it up thinking it was something else, after further review it looks like a bad weld job and it got rusted, ive never inspected the boss that closely until now.

i guess thats life tax for ya,

so now i have no back brakes, i love my combo shifter brake set on this current frame, and i would hate to have to ditch my current brake lever set for something mismatched, is there a good replacement brake that mounts through the fork mount for caliper brakes that will work effectively with v brake levers ?

ive tried caliper brakes with v brake levers in the past, its not a safe thing i would do with back brakes...

also im trying to avoid welding the part back on, this was a curbside special that i have fallen in love with and have alot of sweat equity in... i hope there is an option out there im missing

thanks in advance!

What sort of bike is this? If it's a mountain bike with large knobby tyres, you may have trouble finding a caliper brake that clears the tyre, even if the seatstay bridge is drilled for one. The only thing you can buy that allows V-brake compatible rim brakes without brake bosses is a BMX brake plate, which is effectively an adaptor which bolts to the seatstay bridge like a sidepull brake would and has a set of brake bosses on it. They tend to also have clamps to attach them to the frame, to stop them flexing too much under heavy braking. I haven't seen one for a while, but they do exist.

Other than that, welding/brazing the brake boss back on is the only way.

From the way you're talking, you may be under the impression that the rear brake is the main brake, which it's not. Details here. (http://sheldonbrown.com/brakturn.html)

Without a pic I am sot certain of the amount of the stud left attached.

There is a "problem solver" kit that will work if it is only the barrel part of the boss that broke off.
At one time, I believe Wheels Mfg had a stock kit like this.

The problem solver is basically a bolt and proper diameter sleeve (for the brake to pivot on). The bold threads into what remains of the boss, which is threaded.


A frame builder can likely do the repair and will also have or know how to source a replacement boss as well. Your LBS should be able to point you in the correct direction.

its a trek 700 hybrid\

i use my back brake for general stopping and my front for emergency/quick stopping,

ive looked for those bmx plates.. can't find em anywhere, anybody know a source for these things?

Without a pic I am sot certain of the amount of the stud left attached.

There is a "problem solver" kit that will work if it is only the barrel part of the boss that broke off.
At one time, I believe Wheels Mfg had a stock kit like this.

The problem solver is basically a bolt and proper diameter sleeve (for the brake to pivot on). The bold threads into what remains of the boss, which is threaded.


A frame builder can likely do the repair and will also have or know how to source a replacement boss as well. Your LBS should be able to point you in the correct direction.

i have a little peice left on the frame to work with, i may just have to have it welded... but i don't want to screw around with painting and cobbing it up

+1 ive looked for those bmx plates.. can't find em anywhere, anybody know a source for these things?

something like this might work
http://www.bikeman.com/FS1180.html

take that back

this is probably my best bet
http://www.bikeman.com/FS1067.html

Probably better to fix the broken part then to buy an adapter that mightn't work properly.


Different v-brake adapters

http://www.danscomp.com/489051.php (http://www.danscomp.com/489051.php)

http://billys.co.uk/english/group.php?prod=bsdnvps
http://billys.co.uk/english/group.php?prod=fmit-brakeplate

http://pacecycles.easyspaceshops.com/PACE-RC31-V-BRAKE-MOUNTING-KIT

http://www.winstanleysbikes.co.uk/product/37851/Identiti_Rebate_Forks_Brake_VBrake_Adaptors

http://www.chainreactioncycles.com/Models.aspx?ModelID=33699
http://www.petracycles.co.uk/trailblade-fork-clamp-brake-boss-pair-p-27396.html

…and it just snapped…

Yup! Sound familiar? :rolleyes:

Well, rear-brakes aren't as important as those on the front, so I wouldn't agonize too much! :(
…but seriously, how much torque were you using to snap off the bloody thing? Have you thought about warranty or anything?
- Wil

You should be using your front brake as the primary brake - it is much more effective. I ride with one hand often (holding a dog leash in my right hand) and I cannot imagine trying to stop effectively at all if I only had the rear brake. Except for low-traction situtaions, like riding in snow and ice or cornering on a loose surface, I seldom use my rear brake at all.

All that being said, you do need to get the rear brake fixed. I would guess that getting a new boss welded or brazed on is likely the best solution, or an adapter plate it you can find one.

this bike is old, ive only owned for 10 months or so but i love it, so no chance of a warranty, i think the v brake post was either faulty or there was a crack that i never noticed, im not the original owner, and ive never taken the v brakes off till now,

Probably better to fix the broken part then to buy an adapter that mightn't work properly.


Different v-brake adapters

http://www.danscomp.com/489051.php (http://www.danscomp.com/489051.php)

http://billys.co.uk/english/group.php?prod=bsdnvps
http://billys.co.uk/english/group.php?prod=bsdnvps

http://pacecycles.easyspaceshops.com/PACE-RC31-V-BRAKE-MOUNTING-KIT

http://www.winstanleysbikes.co.uk/product/37851/Identiti_Rebate_Forks_Brake_VBrake_Adaptors

http://www.chainreactioncycles.com/Models.aspx?ModelID=33699
http://www.petracycles.co.uk/trailblade-fork-clamp-brake-boss-pair-p-27396.html

THANKS im sure one of those will work!!

One of those links was a double up, it's been edited and fixed.

I don't think that a v-brake plate would work if you have an existing v-brake boss on one side, you'd have to remove the boss that's still on the fork for it to work.

If I was going to use one the Pace/DMR/Identity adapters or even a v-brake plate I'd probably also want to use a v-brake booster with them to make the brake a bit firmer.

A few examples.
http://www.paulcomp.com/brakebooster.html
http://www.chainreactioncycles.com/Models.aspx?ModelID=8215
http://www.nycbikes.com/item.php?item_id=345
http://www.fahrrad.de/fahrradteile/felgenbremsen-zubehoer/brake-booster-alu/8438.html

Do you have any pics? Unless you live out in the middle of nowhere take this a shop. It is very possible someone with more experience can easily get the remains of the old stud out or if it isn't a screw in stud will have the knowledge and aptitude to thread and tap it for a stud.

I don't think that a v-brake plate would work if you have an existing v-brake boss on one side, you'd have to remove the boss that's still on the fork for it to work.


It wouldn't be hard to mount the brake plate on the underside of the seatstay bridge to avoid the remaining boss getting in the way.

Yeah that'd work.

If ..it's an Aluminum frame, the boss is steel and threaded into the frame,
and so ( given the cause of the problem in the first place,. take it to the Trek Dealer )
To unscrew the remaining boss from the frame, and replace it..

I work at Full Moon Vista on South Ave. bring the bike in and have us look at it. We can give you far more info and advise after looking at it. I have some frame repair capicity if it's steel. Andy.