Cantilever brake headaches...

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In article ,
Mark Hickey wrote:

I will toss on a set of upgraded Kool-Stop pads once the Tektro units
wear down or start to harden - and will probably get even better
performance.


_ I would do that sooner rather than later based on my own
experience with Tektro road brakes, the pads chewed up a rim
to the point of needing replacement before they wore out.

_ Booker C. Bense

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Booker C. Bense wrote:

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If you signed a speeding ticket like that, they'd give you a field sobriety
test.

:-D

Bill "time for Version 2.6./3/?" S.

"Dave" wrote:

Mark Hickey wrote:

What I did was to install a set of (cheap!) Tektro 926AL Mini-V brakes
(obstensibly designed for BMX bikes). Even with the not-too-exotic
pads, they work better than any of the cantis, and don't squeal a bit.
The mechanical advantage seems to be on par with the low-profile
cantis, and the setup is a breeze. I believe that the real
improvement came from eliminating the cable hanger, which was probably
flexing under hard braking. I'm running 35mm tires, and have
clearance to spare, too.

I will toss on a set of upgraded Kool-Stop pads once the Tektro units
wear down or start to harden - and will probably get even better
performance.

Certainly one of the better el cheapo mods I've made on my own bike
lately.

Hey that sounds like a promising solution. Do you think it'd be
possible to run those brakes with 42mm tires?

It depends on the height of the brake bosses, but it's kinda doubtful.
I'm running 35mm Panaracer T-Servs on my 'cross bike, and they measure
36-37mm (imagine that - a tire that's BIGGER than the spec!). There
appears to be about 4mm of clearance to the little "lip" on the quick
release mechanism.

So... since most tires tend to be smaller than the spec, it's possible
- depending on the brake bosses on your fork/frame - that you could
run a particular set of 42mm tires. Or not...

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

Mark Hickey wrote:
"Dave" wrote:

Mark Hickey wrote:

What I did was to install a set of (cheap!) Tektro 926AL Mini-V brakes
(obstensibly designed for BMX bikes). Even with the not-too-exotic
pads, they work better than any of the cantis, and don't squeal a bit.
The mechanical advantage seems to be on par with the low-profile
cantis, and the setup is a breeze... I'm running 35mm tires, and have
clearance to spare, too.

I will toss on a set of upgraded Kool-Stop pads once the Tektro units
wear down or start to harden - and will probably get even better
performance.

Certainly one of the better el cheapo mods I've made on my own bike
lately.

Hey that sounds like a promising solution. Do you think it'd be
possible to run those brakes with 42mm tires?

It depends on the height of the brake bosses, but it's kinda doubtful.
I'm running 35mm Panaracer T-Servs on my 'cross bike, and they measure
36-37mm (imagine that - a tire that's BIGGER than the spec!). There
appears to be about 4mm of clearance to the little "lip" on the quick
release mechanism.

Mark - Are you using standard road levers, then?

Also, you said:

I believe that the real
improvement came from eliminating the cable hanger, which was probably
flexing under hard braking.

It's also good to check how straight your cables are.

I've found most people set up their brakes leaving bends in the cables,
especially the cantilever straddle cables. For example, contrast the
bottom picture with the top picture in
http://sheldonbrown.com/cantilever-geometry.html. The bends in the
bottom straddle cable are slight, but they still need to be
straightened before any braking force is applied. Often the bend is
more pronounced, leading to more wasted motion.

And with cantilevers, straightening that bend means the yoke angle (top
picture) is larger than necessary at the time the shoes contact the
rim. That reduces your mechanical advantage a bit.

I use pliers to bend straddle cables so they run in a straight line, as
in the top sketch. Likewise, I make sure the main cable is straight.
Then, in the usual compromise between mechanical advantage and travel,
I'm starting from the best position I can.

It occurs to me that a flexing cable hanger has sort of the same
effect. A good rigid one would indeed help.

- Frank Krygowski

wrote:

Mark Hickey wrote:
"Dave" wrote:

Hey that sounds like a promising solution. Do you think it'd be
possible to run those brakes with 42mm tires?

It depends on the height of the brake bosses, but it's kinda doubtful.
I'm running 35mm Panaracer T-Servs on my 'cross bike, and they measure
36-37mm (imagine that - a tire that's BIGGER than the spec!). There
appears to be about 4mm of clearance to the little "lip" on the quick
release mechanism.

Mark - Are you using standard road levers, then?

Yes I am - Campy road levers. They are a good match for the Tektro
mini-Vs.

Also, you said:

I believe that the real
improvement came from eliminating the cable hanger, which was probably
flexing under hard braking.

It's also good to check how straight your cables are.

True...

I've found most people set up their brakes leaving bends in the cables,
especially the cantilever straddle cables. For example, contrast the
bottom picture with the top picture in
http://sheldonbrown.com/cantilever-geometry.html. The bends in the
bottom straddle cable are slight, but they still need to be
straightened before any braking force is applied. Often the bend is
more pronounced, leading to more wasted motion.

I found that replacing the straddle cables on my old tandem with solid
Odyssey straddles made more difference than anything else I did.

And with cantilevers, straightening that bend means the yoke angle (top
picture) is larger than necessary at the time the shoes contact the
rim. That reduces your mechanical advantage a bit.

I use pliers to bend straddle cables so they run in a straight line, as
in the top sketch. Likewise, I make sure the main cable is straight.
Then, in the usual compromise between mechanical advantage and travel,
I'm starting from the best position I can.

I set mine up the same way. On the 'cross bike in question, my
braking "power" was fine - it was the squeal that led me to try
something else.

It occurs to me that a flexing cable hanger has sort of the same
effect. A good rigid one would indeed help.

I think this was one of the main problems with the squeal. But mainly
I just wanted to try a pair of the mini-V's...

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame