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Old 09-15-12, 06:29 PM   #1
soymateofeo
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Very Weak Side Pull Brakes

I scored an old univega road bike and have overhauled the whole thing. I have, however, hit a roadblock with the brakes. This is as informative as I can be.
1. The brakes are Shimano BR-Z57 Like these. (http://i.ebayimg.com/t/Used-Shimano-Non-Series-Front-Brake-Caliper-Single-Pivot-Model-BR-Z57-/00/s/NDgwWDY0MA==/$(KGrHqJ,!noE8YJtNFO0BPPbpjM+yg~~60_3.JPG)
2. the handles are similar to these. http://robertobicicletas.com/ebay/sh...8918-30390.jpg

*sorry I don't have pics.

This is the story. The brakes were very weak. They engaged the rim but barely slowed the bike. After they engaged the rim (about 1/4 way), I could continue to pull the lever all the way until they are touching the handlebars and this had little effect on the stopping power. There was about 3 mm of clearance on both sides of the rim.

This is what I have done.
1. changed cable
2. changed housing.
3. changed pads.
4. cleaned the rim with steel wool.
5. I lit a candle and prayed to Jobu.

It changed absolutely nothing. What else can I possibly look for, adjust, etc? It seems that maybe....just maybe....I can see the brake assembly moving a bit after the pad hits the rim. But very little.

thanks!
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Old 09-15-12, 07:35 PM   #2
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Are your rims steel or aluminum? If steel, there is very little you can do to improve brake performance other than new rims.

Also if you are using the "suicide levers" (the side levers) on those brake levers you can never get enough force to operate the brakes well as they are too flexible.
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Old 09-15-12, 08:09 PM   #3
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I agree with Hillrider if your using the extension lever you won't stop just slow down.

Jobu doesn't ride you need to pray to Coppi, Giomondi, or Kelly.

Try a different brake lever like a Shimano 600 non aero and learn to ride 'on the hoods' that should stop you.
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Old 09-16-12, 05:04 PM   #4
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If the rims are alloy, I think the Scott Matthauser( http://www.bikepro.com/products/brak...cono_u_pad.jpg ) brake pads are usually an upgrade in stopping power. I concur that the levers aren't going to work if you are pulling the "safety" levers (and the ones in the photo are about as bad as they get). When setting up your new cables route them as short as reasonably possible to eliminate unnecessary flex and stretch.
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Old 09-17-12, 11:04 AM   #5
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If you really want that top of the bars braking.. Modernize..
Aero, cables under the tape, lever , + interrupter in the housing brake levers,
a separate, additional, lever set.

they are made so the brake cable runs straight thru them,
they tighten the brakes by spreading the housing.. which they interrupt..
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Old 09-17-12, 11:21 AM   #6
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Quote:
Originally Posted by soymateofeo View Post
I scored an old univega road bike and have overhauled the whole thing. I have, however, hit a roadblock with the brakes. This is as informative as I can be.
The brake levers are hopeless. Low mechanical advantage, uncomfortable, flexy and abandon all hope of stopping using the 'suicide levers', as shops call them.

The brake calipers are only slightly less hopeless due to low mechanical advantage and flexy arms.

So turf the levers and calipers. Don't waste your time or risk your safety. A $50 set of Tektro dual pivots with aero levers will stop far better than this old junk ever will.

If your rims are steel, then throw out the wheels too.
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Old 09-17-12, 01:02 PM   #7
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Quote:
Originally Posted by fietsbob View Post
If you really want that top of the bars braking.. Modernize..
Or use guidonnet levers:

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Old 09-17-12, 01:50 PM   #8
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No matter what the brake setup make sure you do not have excessive housing length, as that will reduce the efficiency of transmitting lever movement to the calipers.
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Old 09-18-12, 10:06 PM   #9
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Originally Posted by Dave Mayer View Post
So turf the levers and calipers. Don't waste your time or risk your safety. A $50 set of Tektro dual pivots with aero levers will stop far better than this old junk ever will... If your rims are steel, then throw out the wheels too.
^ Listen to this dude. I modified a bicycle over the summer with the same problems as yours with success. Cheapo single-pivots can be pretty hopeless. Switched to dual pivots and the difference was like night and day.
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Old 09-19-12, 10:02 AM   #10
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Leave the single-pivot on the back. That Shimano brake you tried to link (always leave a space on each side of the link) is easily good enough to lock up the rear.

If you throw a dual-pivot on the back you have to use too fine a touch to avoid skids; it's worse than pointless extra metal.

Definitely prescribe one for the front though. It's how you do stoppies on a road bike.

Also, +1 lose the turkey wings. If you want bartop braking, use interrupters. But bear in mind they require extra skill to set up properly. Those guidonnets look cool (never seen em before!) but I think an aero lever plus interrupter is a better idea overall...

Last edited by Kimmo; 09-19-12 at 10:09 AM.
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Old 09-20-12, 12:19 AM   #11
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Part of the problem is incompatible parts. Those brake-calipers were designed for use with more modern aero levers than what you posted. Aero levers have more leverage to give a stronger yank on the cable when you squeeze them.

Also verify that the brake-calipers aren't binding with too much friction. Disconnect the cable and squeeze the calipers by hand and see how much force it takes. Do the arms pivot smoothly with no crunchiness? Do the arms swing open easily by themselves?

What kind of cables did you get? You'll want teflon-lined cable-housing and inner-cable with a smooth rolled outer surface. Really a HUGE improvement over unlined housing with rough inner wire. This statement shows you have a problem:
Quote:
The brakes were very weak. They engaged the rim but barely slowed the bike. After they engaged the rim (about 1/4 way), I could continue to pull the lever all the way until they are touching the handlebars and this had little effect on the stopping power.
You should NOT be able to pull the lever an additional 3/4 travel after the pads have contacted the rims. This shows a stretched out cable-housing that needs to be compresssed in order to pull the inner wire. Did you pull the new cable-housing through the frame guide? That stretched out the cable-housing. Replace it with new teflon-lined cables and PUSH the housing through. Never pull and stretch it. Always PUSH the cable-housing through the frame-guides when installing.
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Old 09-20-12, 02:09 PM   #12
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I've never found rolled cable necessary for brakes; plain SS cable and lined housing of the right length has always been enough to reduce friction to acceptable levels IME.

But now I've gone to 9spd, I'm wondering if I can get rolled shift cable...
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Old 09-20-12, 02:22 PM   #13
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Rolled? now-a-days, to lower the drag , cables are pulled thru a hard steel die,
it causes the outside to be flattened.. so less friction for the return springs
on the other end, to pull back against..

Click shifting needs, make it common stuff .. Jagwire, and Etc..

Last edited by fietsbob; 09-20-12 at 02:26 PM.
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