Brake problem

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Fred Armour
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Brake problem

Postby Fred Armour » 12 Aug 2009, 6:08pm

My bike is a ridgeback panorama world,which I have had for about a year.It is an excellent bike in every way,with the exception of an ineffective back brake.
The levers pull ok and the brake seems to be working ok,but it is absolutely useless,it barely slows the bike down,whereas the front one would lock the wheel.
I have had the bike to the workshop on a few occasions, and had new cable fitted, then new brake blocks with no success. I emailed ridgeback,who replied quickily,but are at a loss to know what the problem would be. Has anyone got a similiar problem,or advice to resolve it? Any help would be appreciated

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CREPELLO
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Re: Brake problem

Postby CREPELLO » 12 Aug 2009, 6:38pm

The straddle wire may be too long for the brake setup. Fixed (length) straddle wires are a bad idea, reducing the scope for adjustment. For example Avid Shorty's are available with 2 differnt length wires. It was only on closly reviewing the instructions a couple of years after I bought them (with only long wires included) that I realised this and bought some shorter wires which gave a great improvement in performance. A shorter straddle wire will give you more leverage, for your particular brake levers. The old variable length wires are best.

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cycleruk
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Location: Lancashire

Re: Brake problem

Postby cycleruk » 12 Aug 2009, 7:01pm

What angle do you have the straddle wire?

You can increase the mechanical advantage by setting the canti' arms further from the wheel.
This requires the straddle wire to be lowered nearer to the tire allowing the arms to move out.
The pads will have to be reset nearer the rims obviously.

This will increase the force of the pads on the rims.
See Sheldon Brown:-
http://www.sheldonbrown.com/cantilever- ... mechanical

A good setup is to have the cable to arm angle at about 90 degrees.
(point "A" on Sheldons diagram) and the straddle wire as close to the tire ( mudguard) as practically possible.
With too long a straddle wire this angle increases and the pad force reduces.
You may find you will have to fit a shorter straddle wire?

Crepello posted as I write this and comes to a similar conclusion
You'll never know if you don't try it.

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quiksilver
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Location: Cornwall & London

Re: Brake problem

Postby quiksilver » 13 Aug 2009, 4:59am

I don't mean to sound rude but if you practice your braking technique you won't hardly use the rear brake. In my experience a rear brake is only good for shaving off a little speed, the front is the one that does the stopping. Or as an emergency if the front brake fails.

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Mick F
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Re: Brake problem

Postby Mick F » 13 Aug 2009, 8:02am

Sorry, Quicksilver, you're wrong.
Sheldon Brown agrees with you, I must add!

He's wrong too.

Do an experiment if you want.

This subject was debated for a few pages a year or two ago, and I did an experiment going down an incline and braking with front only (very good), rear only (not very good) and both brakes (excellent!)

I'll spend a few minutes digging up the thread from the archives .......
Mick F. Cornwall

fatboy
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Location: North Hertfordshire

Re: Brake problem

Postby fatboy » 13 Aug 2009, 8:09am

My tourer has the same brakes Tektro Orynx on the back as you've got. Basically they're rubbish but I hardly use the back brake! Mine need regular re-lubing of cables and need expensive blocks (Koolstop MTB pads) to do anything. I changed the front brake of my bike for a Tektro CR520 (someone was selling one off and I had a brake judder problem to solve) which improved front braking so much that the fact that the back isn't that good doesn't matter so much. Rather than faffing around with the Orynx brakes (which are rubbish in my (and others CJ for example) opinion) you're best off getting CR520/CR720 (the 720 is the chrome version of the same thing) front and back and some decent blocks.

I know that when you've spent so much money on a bike this is galling but it's really your best option.
"Marriage is a wonderful invention; but then again so is the bicycle puncture repair kit." - Billy Connolly

fatboy
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Location: North Hertfordshire

Re: Brake problem

Postby fatboy » 13 Aug 2009, 8:11am

Mick F wrote:Sorry, Quicksilver, you're wrong.
Sheldon Brown agrees with you, I must add!

He's wrong too.

Do an experiment if you want.

This subject was debated for a few pages a year or two ago, and I did an experiment going down an incline and braking with front only (very good), rear only (not very good) and both brakes (excellent!)

I'll spend a few minutes digging up the thread from the archives .......


Generally Sheldon Brown was right but on this one he was just plain wrong. It's certainly true that the front does the majority but having an effective rear is necessary.
"Marriage is a wonderful invention; but then again so is the bicycle puncture repair kit." - Billy Connolly

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Mick F
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Re: Brake problem

Postby Mick F » 13 Aug 2009, 8:11am

Found them:

viewtopic.php?f=5&t=4869
viewtopic.php?f=5&t=4827

Funny how no-one else carried out their own experiments.
Perhaps everyone knows I'm right?
Mick F. Cornwall

fatboy
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Location: North Hertfordshire

Re: Brake problem

Postby fatboy » 13 Aug 2009, 8:19am

When I were a lad there was a big thing about "going over the handlebars" if you used the front brake only. Given that generally the brakes were rubber on steel with "suicide levers" and didn't really stop there was no way you could go over the handlebars under braking alone but yet wisened old men would tell of the badness of using the front brake too much! Makes me smile now. Mind you I shiver in terror at the two months that I rode a bike with no brakes at all, unless you count shoe rubber and "blakies" as brakes (good sparks though :D )!
Last edited by fatboy on 13 Aug 2009, 2:03pm, edited 1 time in total.
"Marriage is a wonderful invention; but then again so is the bicycle puncture repair kit." - Billy Connolly

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quiksilver
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Location: Cornwall & London

Re: Brake problem

Postby quiksilver » 13 Aug 2009, 1:42pm

Mick F wrote:Sorry, Quicksilver, you're wrong.
Sheldon Brown agrees with you, I must add!

He's wrong too.

Do an experiment if you want.

This subject was debated for a few pages a year or two ago, and I did an experiment going down an incline and braking with front only (very good), rear only (not very good) and both brakes (excellent!)

I'll spend a few minutes digging up the thread from the archives .......


Hmm I did say the rear shaves off speed not that it is pointless. If you get good with the front brake you won't need the rear except in an emergency. But of course using the two together will be better than just the front.

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cycleruk
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Re: Brake problem

Postby cycleruk » 13 Aug 2009, 2:13pm

Well the OP has a tourer which could be fully loaded.
I would think he would like both brakes to function properly. :roll:
We all know the front brakes have more of a stopping effect, but there are situations where it's more prudent to use the back one only.
You'll never know if you don't try it.

fatboy
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Location: North Hertfordshire

Re: Brake problem

Postby fatboy » 13 Aug 2009, 2:27pm

A link to CR720s At £18 it's probably not worth doing anything else.
"Marriage is a wonderful invention; but then again so is the bicycle puncture repair kit." - Billy Connolly

Fred Armour
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Re: Brake problem

Postby Fred Armour » 13 Aug 2009, 8:43pm

Thank you all for some very useful information and links. I now have a better understanding of the braking system,and hopefully be able to sort the problem out, or at least improve it

Russell160
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Re: Brake problem

Postby Russell160 » 15 Aug 2009, 3:22pm

There are two critical factors in brake performance: the brake pad and the wheel rim.

It seems like you've tried various permutations on the first, but not the second. It could be grease or polish on the rims or oil - GT 85 is particularly good at achieving the 'oooh no brakes' effect. Logically, if the kit is the same front and rear, this may account for the difference in performance.

Solutions:
Take wheel off and give good scrub in soap and water.
Rub down rims with methylated spirits.
(You can also get disc brake cleaner which might help if desperate, but I have always found meths does job fine. )

Be sure to not reuse the old brake blocks because if the problem is contamination then the blocks will also be contaminated. You could swap the good blocks from the front as an experiment.

I have heard it suggested to rub the rim down lightly with abrasive paper. Personally, this never seems quite right to me, and the brakes should function well enough without this extreme measure. I suspect its efficacy is because it achieves the decontamination, albeit crudely.
.

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Mick F
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Re: Brake problem

Postby Mick F » 15 Aug 2009, 3:43pm

Sorry, Quicksilver, it's one of my hobby horses!

I don't think it's a matter of being good with the front brake, I think it's a matter of being good with BOTH brakes.

I was giving all this a little thought yesterday, I think it might depend on the bike's geometry and riding position. I think some bikes will lock up the rear very very easily. Mine doesn't, it will lock up, but before that, it works very well indeed and compliments the whole braking system.

Consequently, I invariably use both brakes.
Mick F. Cornwall