Help me brake my bike

welkman

I love my bike. It didn’t cost much from ebay and has served me well so far, however the brakes just don’t work. I want to do some touring and the idea of taking a hill at any speed is scaring the hell out of me. The bike is a Kona Jake circa 2007 and is equipped with avid shorty cantis, did I mention that they are crap? I can’t reach the brifters in order to brake so rely on the top bar mounted levers which works fine. What are my options for replacement? Can I just remove the whole break setup and fit some cheap V brakes? Can I fit standard road type breaks to the frame and fork? Will I need to replace the brifters?

Please help me stop myself :P

W

The Rookie

If you have canti's you can fit V-brakes, but they do need the right lever's with the right pull ratio or they will be worse than canti's!

Canti's can be made to work fairly well (they have served cyclocross well enough for a fair few years) so maybe its time for a check over, decent pads, well lubed cables (due to the short cable travel its more of an issue than with V-s) and pivots and making sure they are correctly adjusted all help (bridge form over the tyre is crucial).

My daughter can do a stoppy on her basic Shimano Canti's (alivio arms and STX levers) on her commuter (OK she is sub 8.5 stone which helps).

Simon

welkman

Thanks, I will give stripping them down a go. When setting them up I find it hard to stop them rubbing, they do not seem to recoil as they should which means I need to allow loads of room between the pad and the rim. Any reccomendations on pads?


W

Mr Plum

koolstop pads should sort you out.

cjcp

I have the same bike and the same problem.

I'm using Avid pads, but they're not great. I think the Koolstops for MTBs are compatible, but not tried them yet.

One thing I haven't tried yet is to drop the front brake cable hanger to just above the fork (it's presently just below the stem). They need constant adjustment. I've tried closing my eyes and praying, too, but that doesn't seem to slow the bike either.

Keep them clean and lubed around the area of the bosses.

The Rookie

If they aren't returning properly that could be a sticky cable or arm.

Koolstops are meant to be very good (never tried them myself).

Simon

UndercoverElephant

You could swap the cantis for some mini-Vs, I believe they use the same pull ratio as the cantis and are a lot easier to set up.

dhope

The Beginner wrote:

Koolstops are meant to be very good (never tried them myself).

Simon

Koolstop Salmon, not Koolstop Simon

I'll get my coat

mudcovered

welkman wrote:

The bike is a Kona Jake circa 2007 and is equipped with avid shorty cantis, did I mention that they are crap? I can’t reach the brifters in order to brake so rely on the top bar mounted levers which works fine. What are my options for replacement? Can I just remove the whole break setup and fit some cheap V brakes? Can I fit standard road type breaks to the frame and fork? Will I need to replace the brifters?

Right your options without changing the brifters are:

1.Mini V's

2. A different Canti brake.

I can't really comment on the Mini-V's but I got better results when I switched from the Avid provided pads to Kool stop dual compound. However I didn't get truly good results until I changed the front brake to a Kore Race cantilever brake. It is a a completely different design to the Avid brake with a lot more flexibility in the way it is set up. This brake change also got rid of the serious juddering issues I got with the Avid's. Since this change I've now got enough confidence to go quite fast downhill and be confident in the performance of the brakes. You can get the Kore Race brakes from chainreaction for about £30.

This was all on a 2008 Jake the Snake. I'm now planning on doing the same substitution on the rear brake as the return spring mechanism in the Avid has gotten seriously sticky on the rear brake causing one of the pads to rub occasionally. If you have the Jake with a steel fork it might have disk tabs. If you were willing to replace the front wheel you could switch to a cable pulled disc brake. Just make sure you get one designed for road levers not MTB ones.

Mike

jejv

Canti leverage (mechanical advantage) is most sensitive to the angle of the straddle cable to the horizontal (assuming the brakes are vertical).

Mechanical advantage is (to a good approximation) inversely proportional to the angle to the horizontal of the straddle cable at the biting point. Halve the angle, double the leverage.

So to increase mechanical advantage, make the straddle cable as short (near horizontal) as possible.


Canti leverage is much less sensitive to the angle between the pivot, the point the straddle cable joins the canti arm, and the straddle cable. Call that angle "C". Adjusting pad spacing to make angle "C" close to a right angle will slightly increase leverage. The dependency is on sine(C), and sine(C) ~=1 for C even vaguely close to a right angle, for example sine(60 degrees) ~= 0.866.

Some instructions suggest that this second point is more important than the first, trying to tell you to make angle "C" a right angle, and then stop. This is wrong.

We have two bikes with CR520s with Koolstop MTB pads. They're set up with the front straddle as low as possible, and the rear straddle quite high, so the rear brake has less leverage, is a bit harder to lock, and needs less adjustment.

welkman

Right, first of all thanks for the help.

I think I am going to take the plunge and buy a front kore race brake and some kool stop pads for front and back. Lets see if that stops me from mounting the car in front of me on the way to work.

Cheers

W

mudcovered

jejv wrote:

Canti leverage (mechanical advantage) is most sensitive to the angle of the straddle cable to the horizontal (assuming the brakes are vertical).

We have two bikes with CR520s with Koolstop MTB pads. They're set up with the front straddle as low as possible, and the rear straddle quite high, so the rear brake has less leverage, is a bit harder to lock, and needs less adjustment.

This is part of the problem with the Avid Shorty fitted to older Kona Jakes. They effectively have a fixed straddle cable length making mechanical advantage impossible to tune. I could get them to stop OK but then I couldn't get the straddle cable out of the hook to change the wheel. When adjusted to allow that at the front the stopping power was less than stellar.

Mike

cjcp

mudcovered wrote:

jejv wrote:

Canti leverage (mechanical advantage) is most sensitive to the angle of the straddle cable to the horizontal (assuming the brakes are vertical).

We have two bikes with CR520s with Koolstop MTB pads. They're set up with the front straddle as low as possible, and the rear straddle quite high, so the rear brake has less leverage, is a bit harder to lock, and needs less adjustment.

This is part of the problem with the Avid Shorty fitted to older Kona Jakes. They effectively have a fixed straddle cable length making mechanical advantage impossible to tune. I could get them to stop OK but then I couldn't get the straddle cable out of the hook to change the wheel. When adjusted to allow that at the front the stopping power was less than stellar.

Mike

Yep. Fine-tuning just isn't possible. I thought about cutting the straddle cable length down, but not convinced that will work. May plump for those Kona Races you mentioned. Nice one.

ride_whenever

take them off and fit some hs33/hs11's modifying the lever to work as an interrupter.

Simples

jejv

ride_whenever wrote:

take them off and fit some hs33/hs11's modifying the lever to work as an interrupter.

Err, OK, but this might be cheaper, if you don't mind sticky-out brakes:
http://cgi.ebay.co.uk/tektro-cr-520-fro ... 0447233635

That is a set of Front & Rear CR520s.

Get's a bit more expensive when you add in the Koolstop Simons...

welkman

any thoughts on the ebay bargin, seems too good to be true?

W

snailracer

cjcp wrote:

mudcovered wrote:

jejv wrote:

Canti leverage (mechanical advantage) is most sensitive to the angle of the straddle cable to the horizontal (assuming the brakes are vertical).

We have two bikes with CR520s with Koolstop MTB pads. They're set up with the front straddle as low as possible, and the rear straddle quite high, so the rear brake has less leverage, is a bit harder to lock, and needs less adjustment.

This is part of the problem with the Avid Shorty fitted to older Kona Jakes. They effectively have a fixed straddle cable length making mechanical advantage impossible to tune. I could get them to stop OK but then I couldn't get the straddle cable out of the hook to change the wheel. When adjusted to allow that at the front the stopping power was less than stellar.

Mike

Yep. Fine-tuning just isn't possible. I thought about cutting the straddle cable length down, but not convinced that will work. May plump for those Kona Races you mentioned. Nice one.

You CAN increase mechanical advantage, thereby increasing stopping power, even if your straddle cable length is fixed, by remounting the brake blocks further inboard (i.e. don't push the blocks up against their arms when mounting). You will need to let out some brake cable first, to maintain the normal 2mm or so clearance between brake block and rim. Your straddle cable will end up hanging lower.

You might have noticed that letting your brake blocks wear away and shortening the brake cable to maintain correct clearance is the opposite of the above, and results in decreased mechanical advantage i.e weaker braking.

cjcp

snailracer wrote:

cjcp wrote:

mudcovered wrote:

jejv wrote:

Canti leverage (mechanical advantage) is most sensitive to the angle of the straddle cable to the horizontal (assuming the brakes are vertical).

We have two bikes with CR520s with Koolstop MTB pads. They're set up with the front straddle as low as possible, and the rear straddle quite high, so the rear brake has less leverage, is a bit harder to lock, and needs less adjustment.

This is part of the problem with the Avid Shorty fitted to older Kona Jakes. They effectively have a fixed straddle cable length making mechanical advantage impossible to tune. I could get them to stop OK but then I couldn't get the straddle cable out of the hook to change the wheel. When adjusted to allow that at the front the stopping power was less than stellar.

Mike

Yep. Fine-tuning just isn't possible. I thought about cutting the straddle cable length down, but not convinced that will work. May plump for those Kona Races you mentioned. Nice one.

You CAN increase mechanical advantage, thereby increasing stopping power, even if your straddle cable length is fixed, by remounting the brake blocks further inboard (i.e. don't push the blocks up against their arms when mounting). You will need to let out some brake cable first, to maintain the normal 2mm or so clearance between brake block and rim. Your straddle cable will end up hanging lower.

You might have noticed that letting your brake blocks wear away and shortening the brake cable to maintain correct clearance is the opposite of the above, and results in decreased mechanical advantage i.e weaker braking.

Do you need to swap the washers over to the wheel side of the brakes?

japsy

welkman wrote:

....I can’t reach the brifters in order to brake so rely on the top bar mounted levers which works fine.....

You sound happy with the responses but when I read your original post, I read it that you physically can't reach the brake levers. If that is the case, then I'm not sure how changing from canti's to v's can help.

jejv

japsy wrote:

welkman wrote:

....I can’t reach the brifters in order to brake so rely on the top bar mounted levers which works fine.....

You sound happy with the responses but when I read your original post, I read it that you physically can't reach the brake levers. If that is the case, then I'm not sure how changing from canti's to v's can help.

Yeah. If they're shimano brifters, you need to try the 4 degree spacers, then the bigger spacers.
These spacers should have come with the brifters, but I believe they can be got afternarket. ?sjs?

Otherwise, moving the levers down round the bends a bit might help, and tilting the bars up to match.

Why don't drop-bar levers just have reach adjustment screws like flat-bar levers ???

jejv

welkman wrote:

any thoughts on the ebay bargin, seems too good to be true?

That's exactly what we've got.

Not spotting the different branding, I was a bit suprised when they turned up.
But after close examination, it seems that they are CR520s, but with "Colorado" printed on the arms instead of "Tektro". The pads say Tektro - but I don't plan on using them.

snailracer

cjcp wrote:

snailracer wrote:

You CAN increase mechanical advantage, thereby increasing stopping power, even if your straddle cable length is fixed, by remounting the brake blocks further inboard (i.e. don't push the blocks up against their arms when mounting). You will need to let out some brake cable first, to maintain the normal 2mm or so clearance between brake block and rim. Your straddle cable will end up hanging lower.

You might have noticed that letting your brake blocks wear away and shortening the brake cable to maintain correct clearance is the opposite of the above, and results in decreased mechanical advantage i.e weaker braking.

Do you need to swap the washers over to the wheel side of the brakes?

No, keep the washers in their original order. The washers are not there for spacing, they are "spherical" washers designed to magically grip the block posts anywhere along their length and at any angle. They are quite ingenious, really. Make sure you tighten them up fully, though, a brake block coming loose and jamming in the spokes will really spoil your day.

Canti brake blocks usually come with a long and very solid post so you can mount them anywhere along that post. This is not really to allow riders to tune the braking force (although it does), it's more to accommodate different wheel rim widths so it is safe to do, you are not doing anything beyond their design. Some block posts even have gradations stencilled into them, so you can more easily mount both posts with the same amount of spacing from the brake arms.

cjcp

snailracer wrote:

cjcp wrote:

snailracer wrote:

You CAN increase mechanical advantage, thereby increasing stopping power, even if your straddle cable length is fixed, by remounting the brake blocks further inboard (i.e. don't push the blocks up against their arms when mounting). You will need to let out some brake cable first, to maintain the normal 2mm or so clearance between brake block and rim. Your straddle cable will end up hanging lower.

You might have noticed that letting your brake blocks wear away and shortening the brake cable to maintain correct clearance is the opposite of the above, and results in decreased mechanical advantage i.e weaker braking.

Do you need to swap the washers over to the wheel side of the brakes?

No, keep the washers in their original order. The washers are not there for spacing, they are "spherical" washers designed to magically grip the block posts anywhere along their length and at any angle. They are quite ingenious, really. Make sure you tighten them up fully, though, a brake block coming loose and jamming in the spokes will really spoil your day.

Canti brake blocks usually come with a long and very solid post so you can mount them anywhere along that post. This is not really to allow riders to tune the braking force (although it does), it's more to accommodate different wheel rim widths so it is safe to do.

I was looking at the spherical nature of the washer on the outside of the block and couldn't see how that would fit on the wheel side. Haven't checked the post, though, so will do that at lunchtime. Cheers.

Failing that, I'll buy some new brakes. Do the Kona Races or the Tektros squeal as much as the Avids? It's enough to startle wildlife.