V-brakes a bit disappointing - advice?

[swee'pea99]

Put the next-to-final touches to my frankenstein bike over the weekend, and I have to say it's a wonderful ride. The only slight fly in the ointment is that the brakes don't have anything like the stopping power I'd anticipated. I mean, they're not that bad - they do stop the bike, and reasonably quickly at that. But nothing like as good as the (caliper) ones I have on my (racer) #1 bike.

Am I expecting too much? I've set the cross wires to sit at rest about three fingers above the tyres, based on something I read somewhere. Can I/should I increase the braking force by decreasing/increasing that distance? Or any other suggestions/advice very much appreciated.

 

[HLaB]

I'll see if I can find the link but I've seen a small wheel thing attached to a Tandems front brake and the rider says its really effective; I've got one too but I've not fittted it yet. Basically the cable goes through a small wheel and that pull is magnified by a large wheel.

Edit, this is the thing unfortunately it a US site

Edit2: sjscycles link, travel agents

 

[bonj2]

get disk brakes

 

[fossyant]

Not if your frame won't take them !!!

 

[NickM]

Which brake levers are you using?

V-brakes don't really lend themselves to tuning as cantis do (unless you have Avid Speed Dial levers, anyway). They work best when mounted on bosses 80mm apart and 25mm below the brake track. If yours are set up like that, the only thing you can do is change the brake blocks. Koolstop salmon are generally accepted to be the best.

 

[swee'pea99]

Thanks for responses. I was getting a bit down...seemed to be suggesting that the things can't be expected to work properly - or not without adding £18 bits to them. (And no, I won't be lashing out on disc brakes - this is very much a *budget* frankenstein.)

To answer your question, NickM, these ones. And the brakes themselves are these. I put new Jagwire blocks in them - are they no good? Will Kool-Stops make a significant difference?

 

[MartinC]

Swee'pea. Unfortunately Shimano BR-550's aren't V Brakes - they're cantilever brakes. They're compatible with STI/Ergo levers but their performance is nowhere near as good as V Brakes. They haven't even got a good reputation for performance amongst canti brakes. The double pivot short reach caliper brakes on your othe bike will certainly perform much better.

 

[swee'pea99]

 

[NickM]

You have a mismatch between brake levers and brakes - too much cable pull at the lever, not enough mechanical advantage, resulting in feeble braking (and I expect you have to squeeze the levers really hard?).

Do not despair; to fix it, all you need do is fit some V-brakes like these.

I would try them with the original blocks first. They will certainly be an improvement over the set-up you have now.

 

[RedBike]

I've set the cross wires to sit at rest about three fingers above the tyres, based on something I read somewhere

Errrm, V-brakes don't have cross wires?

..............

I've just read the rest of the thread. You have cantilever brakes; and to make matters even worse they're optimised for use with drop bar road levers. They will sort of work with your current levers but they'll never be great. Try maing the straddle wire as long as possible to compensate for the fact that your levers are pulling too much cable.

The Acena brakes linked to above are alight. But if you want stopping power go for the LX brakes (or better) like these http://www.merlincycles.co.uk/?fn=product&productId=652&categoryId=90
They have a second pivot in there which keeps the pads correctly aligned with the rims as the pads wear out. These should be an improvement on your road bikes calipers!

 

[NickM]

...The Acena brakes linked to above are alight. But if you want stopping power go for the LX brakes (or better) like these http://www.merlincycles.co.uk/?fn=product&productId=652&categoryId=90
They have a second pivot in there which keeps the pads correctly aligned with the rims as the pads wear out...

...and are known for their tendency to squeal, especially when the pivots get worn. I'd save the money, if I were you.

 

[swee'pea99]

Thanks all. Jimboalee has been telling me how to get the best possible performance out of them, so I'll be trying that first. If that doesn't work, I guess I'll have to get some real V brakes like the ones NickM kindly highlights. They seem like the bidniss, and very good value. Not nearly as pretty as the ones I have now tho'....*sniff*

 

[02GF74]

as you now know, you don't have v-brakes.

the brake levers almost certainly are for use with v-brakes and due to the different cable pull for cantis (which you have) aren't going to be as effective.

properly set up v-brake system will have you over the bars and picking your teeth off the tarmac, so get a feel of them first before squeezing those levers.

 

[jimboalee]

From what I remember, there are two types of brake lever. Levers to fit drops and levers to fit straight handlebars.
Nowadays they incorperate the gear selecting mechanism.

The amount of cable movement is dependent upon the mechanical advantage of the brake itself. Sweepea's cantis have 2:1. V brakes have 3 or maybe 4:1.

Here is a Weinmann 570 with a 1:1 mechanical advantage, which would pitch the rider over with a sharpish pull.

The greater the MA, the greater the cable travel to take up the blocks' movement.
Sweepea's cable will travel approx 5 - 6mm, so any lever to fit a straight handle bar will work fine.

 

[swee'pea99]

Had a go at adjusting the brakes as per Jimboalee's v helpful directions and bingo! Transformation! Still not as good as the 105 setup on my regular road bike, but given a good hard squeeze, they now stop both wheels dead...which is good enough for me. Didn cost me nuffink neeva. Thanks Jimboalee!