Rear brake: Pedal travel

chrisf

Over 1,000 Posts
Hi all:

This has been agrivating me since riding my bike. I've tried everything and cannot figure out the proper pedal ratio. On these old bike with rear drum brakes, how much should the brake pedal travel? On mine, I waste 1" just getting the shoes to touch the drums. Then I use another 1/2" just applying the brakes. By this time, my body is twisted into an odd position. So you folks with rearsets, how much travel do you have? Also, how much work does the rear brake actually do? Right now, I baiscally just use my front brake exclusively.

--Thanks, Chris
 
CafeRacerSide.jpg


Chris, looking at your rearset design I can see why you aren't getting enough braking force when applying the lever. There's not enough mechanical advantage in the setup. You've shortened the brake hub lever and used a bent brake rod to the back of the foot lever. The most popular setup is to flip the original brake hub lever upsidedown to point up and the brake rod over the swingarm then attached to a foot lever that has an elbow pointing up to connect the rod.

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There should be very little travel in the brake pedal before making contact. You want to be able to make the rear brake light activate without engaging the brake for signalling people behind you, but just by touching the lever. Beyond that you want the brake engaging.

I agree though that your brake hub lever is WAY too short. Go back to a stock length and run it like DRJ has suggested or run a straight rod to it on your current setup. Adjust the length of the rod/position of the hub lever to get the pedal to the right position for your foot.
 
cheers drj. Since that picture, I've bought a stock lever, and I'm still having problems. I'll try your mounting method and see how it goes. I should have also mentioned that I've since made a tradtional 90 degree rear control for the brake side.

How much pedal travel should I expect?

--Thanks, chris
 
Thanks TinTin. I'll implement those suggestions. One thing thought: on my cb350 hub, I can move the stock brake lever around 3/4" before the shoe touches the drum. I'll work on the leverages, but it seems like it will be a struggle to "take up that slack". The guy that put my tires on claim my shoes looked great, so I don't think it's that.

Should the leverage be progressive or regressive?

DrJ: can you post a pigs of your setup?

--cheers, chris
 
chrisf said:
Thanks TinTin. I'll implement those suggestions. One thing thought: on my cb350 hub, I can move the stock brake lever around 3/4" before the shoe touches the drum. I'll work on the leverages, but it seems like it will be a struggle to "take up that slack". The guy that put my tires on claim my shoes looked great, so I don't think it's that.

Should the leverage be progressive or regressive?

DrJ: can you post a pigs of your setup?

--cheers, chris

Wow, Chris that seems like a lot of travel. I have put new shoes in my CB rear hub, and my stock arm literally moves 1/4" before the shoes hit the hub. I'll go home tonight and confirm this. But did you put new shoes in your hub? Sounds like it may be a situation with the system itself and not the controls...

Steve
 
sclay115 said:
Wow, Chris that seems like a lot of travel. I have put new shoes in my CB rear hub, and my stock arm literally moves 1/4" before the shoes hit the hub. I'll go home tonight and confirm this. But did you put new shoes in your hub? Sounds like it may be a situation with the system itself and not the controls...

Steve

that sucks. I do have a spare hub with a lot of shoe left on it that I could try. I think the first step will be to mount it from above. Step two will be to replace the hub.

Thanks gents. I feel like I'm much closer to sorting...

--Chris
 
Here's my rear brake setup. I bought these from a racer that had them made. A bit unusual design since the footpeg is not part of the foot lever pivot. This is a bit of a flaw because the foot lever is about the same length as the elbow lever, thus not gaining any mechanical advantage. The foot lever should be at least twice as long so I'm going to have a longer foot lever welded on. The lever travel is nice and short but the brake doesn't grab enough for effective braking. I also welded an adjustable stop tab and added a return spring. Now I need to figure out how to install a brake light switch.

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So there's no fear of the swing arm hitting the pull-rod? i suppose I get VERY little travel out of my swing arm and I sit right over the thing.

I'm going to sort this tomorrow, well I need to order new rod ends dues to a mishap :(

--Chris
 
DrJ

Two questions -as the swing arm travels through it's arc does that effect the braking (since swing arm pivot and brake lever are in two different locations?)

If you could add some close ups of your set up. My 350 ice bike uses the rear pegs as rearsets and the brake is still in the same spot - yes this means foot right off the peg to dab the brakes.

I'm especially interested in how I can have a brake lever pivot on the same axis as the ridgidly mounted peg. (Chris maybe you can chime here?? Pics are always good)

But let's face it brakes just slow you down - Who needs that?
 
zixxerboy said:
DrJ

Two questions -as the swing arm travels through it's arc does that effect the braking (since swing arm pivot and brake lever are in two different locations?)

If you could add some close ups of your set up. My 350 ice bike uses the rear pegs as rearsets and the brake is still in the same spot - yes this means foot right off the peg to dab the brakes.

I'm especially interested in how I can have a brake lever pivot on the same axis as the ridgidly mounted peg. (Chris maybe you can chime here?? Pics are always good)

But let's face it brakes just slow you down - Who needs that?

The swingarm movement doesn't affect braking. The action is the same as stock only it's above the swingarm. Most vintage racers use a similar setup so I assume they know what they're doing. And their pivots are usually where the footpeg is. Mine was custom made but I find the design flawed because I don't have enough leverage with the foot lever. Rearsets are always finicky on vintage bikes, they rarely bolt on and work perfectly.
 
Dr J

So it would appear that the hub lever works a two sided cam and can work in either direction. Your moves the lever clockwise, while Chris moves Counter CW. That's makes it way easier to sort out.
 
zixxerboy said:
Dr J

So it would appear that the hub lever works a two sided cam and can work in either direction. Your moves the lever clockwise, while Chris moves Counter CW. That's makes it way easier to sort out.

That is correct, the brake shoe cam rotates in either direction. But moving the brake hub lever to the up side requires a bit of spline grinding.
 
DrJ said:
That is correct, the brake shoe cam rotates in either direction. But moving the brake hub lever to the up side requires a bit of spline grinding.

Couldn't you effectively flip the cam inside the hub? I did this once on assembly by mistake, fixed it, and then have come to find out it needs to come back apart for me to flip it again.

Steve
 
sclay115 said:
Couldn't you effectively flip the cam inside the hub? I did this once on assembly by mistake, fixed it, and then have come to find out it needs to come back apart for me to flip it again.

Steve

The Honda rear brake cam is symmetrical and works in either direction. Flipping it upside down does move the flat spot on the splines to the other side so the brake hub lever can mount upside down. But you may still need to file down a couple of splines to get the best alignment. Anyway I'm growing weary of this topic. If you want rearsets you have to make them work yourself.
 
DrJ said:

The brake hub lever and the foot pedal lever should have the lever ends where the brake pull rod mounts close to parallel to each other. This is where you would get your mechanical leverage back. Right now, the foot lever has more of an up pull than a foward pull and gives very little travel in the hub lever when the brake pedal is depressed. The present brake pedal probably has to be depressed to close to vertical before it starts to have a substantial foward pull that is needed to activate the rear brake.
DG
 
At the risk of pissing off the good Doc ( :) ), this is what I came up with. It isn't perfect--as you can see from the pictures. It still has about 1 1/4" of travel just to take up the slack. When I replace the sprocket, I'll swap hubs with another I have.

Static:
BrakeControlsStatic.jpg


Depressed (slack taken out):
BrakeControlsEngaged.jpg


--Chris
 
chrisf said:
At the risk of pissing off the good Doc ( :) ), this is what I came up with. It isn't perfect--as you can see from the pictures. It still has about 1 1/4" of travel just to take up the slack. When I replace the sprocket, I'll swap hubs with another I have.

It wasn't you that was getting to me, it's just that the topic went in several directions and I got sidetracked from the initial problem. Chris, your new setup looks much better than befor and should work. That much travel sounds to me like the shoes are worn or worse the steel brake liner in the hub is worn past the minimum diameter spec. Shoe lining should be min. .1"/2.5 mm and the max. inside brake drum diameter should be 6.38"/162 mm. Stock lever travel is 1". Ideally your brake hub lever and foot lever elbow should be parallel but your setup should still work. It would also help if your brake hub lever was longer than the elbow. Nice parts you've made, very sano.
 
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