[Closed] BMX brake Q

I think its called an elevated U brake i.e the pivots are above the pads?

A mini v won't work as the brake bosses will be in the wrong place - stick with the U brake but just run a straight cable from the existing lever to the brake straddle. You can remove the gyro.

Cheers mamadirt I thought you might reply. Only problem there is that the stradle takes two cables and the cable guides are either side of the seat tube.
I'll have to look at some shop models.

What type of brake caliper is on there already?
You can run a single cable but the norm with a U brake is for it to split prior to the seat tube (think a bit like older cantilever brakes). The brake mounts must be on the u/s of the seat stay for this to work or on top of the chain stay.

Gyros are a pig to set up properly. If you want to remove it completely you may have to remove the top headset cup if the frame doesn't have gyro tabs on the head tube.

You could miss out the gryo and just run a full length cable.

To be honest though is probably just needs a little care and attention. If you haven't experience of them they are a right pain to set up. First strip down the rear brake and clean up everythng, take some wet & dry paper to the pivots and make them smooth as a baby's butt. Clean up the inside of the brake arms where they come into contact with the pivots. Then look in the brake arms where the return springs go, are there little plastic sheaths in there? If so then ditch them, they're supposed to keep dirt out but they just keep it in and cause problems.
Okay, now check the bolts haven't squashed the tops of the pivots, if they have then take a fine file and make them smooth again.
Now, grease up the pivots and reassemble everything. Get a good bit of tension into the return springs - make sure you turn them the corect way, haha!
Now you have that end all back together check the condition of your cables. They might look okay but how good are they? Often these bikes are left outside or in the rain etc so they may look okay but there not great inside, there could be a fair bit of stiction. You can try sending oil down them, it'll certainly help.
Finally, take your time and set up the cables properly, it's well worth doing this as once you get it all balanced properly it'll work really well.
And finally, check the pads. More often than not these bikes are supplied with cheap pads which may as well be plastic for all the good they do. Back in the day I used to use Kool stop pads which were nice and soft. Not sure if you can still get them (they were in the shape of a trainer!) but I'm sure there will be something similar out there.

Hope that help. Bar spins ahoy!

Easy, just get a long straddle wire (or brake wire) run that either side of the seat tube, then you can just hook up a standard cable to that.

Is it a Mongoose per chance?

OK problem is the existing U brake requires two cables pulling it at the same time.
There is'nt a centre mounted stop to run an adapted brake.

Yep, good tips there from Zedsdead but if you're set on ditching the gyro then a long straddle wire (think oldskool cantis) as ziggy says, will do the trick.

These 'U' brakes are generally pretty useless.

If you have 2 cable end stops either side of the seat tube, you are pretty stuck with a 2-cable run, with all it's inefficiencies.

Best bet is to strip the lot down and make sure all the pivots and cable runs are clean. Lube the pivots when you reassemble, and lube the cables. Also lube the top cable, where it initially splits into 2 as well - lots of friction here too.

The only other option is to drill a hole for a direct cable run from the lever. If the brake is mounted down on the chainstays, which makes life awkward, you could drill through the seat tube and fit a threaded cable stop / adjuster on the front side.

Good Luck.........

edit - slow typing - just seen the other comments. 🙂

OldGit - Can you post a picture or 2 of the last stages of the brake cable/brake and I will get a couple from my bike for you to see how most bikes will be set up.

If you have 2 cable end stops either side of the seat tube, you are pretty stuck with a 2-cable run, with all it's inefficiencies.

I thought that when building up a midschool S&M bike earlier this year, but ran my straight cable to just one of the guides- slightly off centre but all that evened up when I set the brake spring tension and it worked fine.

slightly off centre but all that evened up

Good plan - I'd never have thought that would work, but I s'pose once one pad is on the rim, the other has to follow, and if you offset the spring tensions, they'll pretty much move together...

That's worth a try then. Our brakes don't have any spring tension but I'll risk buying one.

If your brake has no tension then that's half your problem.

The spring is hidden within the brake arm around the pivot. You use a spanner to move the flats around the allen bolt.

If you're near Glasgow I can set it up for you. I just set up my 6 year olds sons after a winter of abuse. It works perfectly again now.

Neither brake has any form of tensioning.

They do, there may be no tension in them at the moment but they do. Otherwise they would do nothing. Which they probably are due to having no tension...

See the flats...

[img] [/img]

The spring is contained within that.

To clarify - the green bits around the pivot bolts, the springs are contained within, and to increase spring tension, loosen the allen bolt, add tension with a 13mm(?) spanner and while holding the spanner in place, re-tighten the allen bolt. To add tension turn the spanner clockwise on the left hand side, anti-clockwise on the right (as looking from the rear or the bike)

If you could get a couple of pictures of the cable routing on the frame I may be able to help with setting up a single cable system.

Just get rid of the brake and ride brake less

bmx brakes are easy to dial in.

mine stop on a dime

Cheers.
Got a straddle clamp for a singe cable, a decent linear? BMX cable and have routed off centre and it all works.
Thanks Mamadirt for that and Zedsdead for the heads up on tensioning.
I missed the whole BMX thing as you may have guessed.

i love my mobeous giro with london mod. works better than single cable

Jedi
That sounds to me like you've injected Novocaine into your fingers.
Gibberish man whatever happened? you were a good honest decent roadie once.

heh heh

i am a cyclist!