Early 90s Bike Side pull Brakes Not moving Evenly.
 

It's a Medici Road bike. Love the bike but can't get the left side to move the same amount as the right side (Facing the bike as I write this). My hybrid bike had different brakes where I could tighten a screw to adjust spring tension but this one doesn't have that. How do I fix this? The right seems to be contracting more than the left if that makes sense.
https://cimg2.ibsrv.net/gimg/bikefor...d752c7fb38.jpg
I know the pads have moved out of alignment again and I will fix that. I will also center the calipers. Just learned how to do that.

Some were almost impossible to keep centered. If you are going to keep riding it and don't have a overwhelming desire for period components, then you'll find dual pivot brakes much better in all respects. They usually have a adjustment to help you get them centered and they stay centered.

And if the brake pad wasn't dragging enough to slow me down, then I wasn't one to worry much about those that wouldn't stay centered. The pads left and right didn't show much difference in wear.

Sigh... old single pivot brakes. At least these aren't labelled: 'Dia-Compe'.

First order of business is to replace these with some dual-pivot road brakes; cheap Tektro dual pivots feature much better mechanical advantage and they self center. You center them by grasping both arms and rotating the whole caliper, and then they stay put, unlike single-pivot brakes.

If you really insist on staying with these, and I've worked on hundreds of such brakes, here is a checklist of possible solutions:

• Rotate the whole brake around the central bolt. This may require loosening the mounting bolt on the back of the fork, rotating, and then tightening. Or perhaps there is a 13mm flat on one of the bolts that you can get a wrench into to rotate the whole thing.
• Perhaps the arms are gummed up or corroded and sticky. Lubricate the pivots with a drop of Tri-Flow or whatever.
• Perhaps the cable housing is too short or too long, which pulls the brake one way or the other. Size correctly. In any case, replace cables and housings yearly.
• Possibly the central bolt is too tight, and the 2 arms are not free enough to rotate around the central bolt. 10 degrees of rotation could mean the difference between the arms being seized up, or too loose and floppy. Tune them carefully.
• Is the main spring broken or bent?
• At the interface where the spring pushes on both arms: lubricate with a drop of something. Don't get any lube on the rims.

take them completely apart... clean EVERYTHING... reassemble with proper clearances to allow free movement with minimal slop... DON'T GREASE them since the grease will eventually CAUSE sticky operation.,,, Correctly center them to the wheel/frame.

ride your now better functioning bike and smile.... right after you ALIGN THE LEFT PAD TO THE RIM SURFACE.

Great suggestions all. That suggestion that the center bolt might be too tight is especially pertinent. It seems like there was a lot of play when I first got the bike so I tried tightening it. It's possible I overtightened. Sounds like these single pivot brakes are going to be fiddly. If I still have the bike this winter maybe I'll ask for a dual pivot for Christmas. The brake is ok as is I guess. It works but I can't some to a skid stop right now for sure

I'm just glad the brakes don't squeal like my Trek/Giant bikes did

Completely disassembling and cleaning them is the way to go at this point. (I usually apply a little light oil when reassembling.)

When adjusting the brakes so that the pads meet the rim at the same time, you may find that the gaps are slightly different when the brakes are completely open. Try not to let that bug you too much. ;)

Replace the springs and buy a "brake wrench" that allows you to tighten the bolt completely and then make adjustments to orientation of the calipers. The wrench is thin enough to use on the flat rear end of the caliper. Park Tool sells the OBW Offset Brake Wrench - Brake Centering Tool for this purpose.

There's nothing wrong with the brakes. It's important that they're mounted so they're centered in the open position and that's it.

As for closing evenly, they operate on the same principal as your hands.

Try this experiment. Put a glass on the table at hand's reach where you can reach it with your eyes closed. Now, with eyes closed, reach out and pick it up. Do this a few times, and you'll see that as you close your grip, one finger touches first, then the opposite side closes, and the grip tightens until you can lift it.

Same with a brake, one side touches, then when the second touches, Newton's Laws ensure that the rim is squeezed evenly from both sides.

Looking at the cable angle; the cable housing is too short, pulling the brake to one side. Replace cables or lower bars.

Yup, cable is way too short.
https://cimg1.ibsrv.net/gimg/bikefor...c955a122d5.jpg

Ugh...say it ain't so. Maybe I'll just live with it for now. If I still have the bike during the winter maybe I'll take it to a shop.
The cables have been taped down as well maybe when I re-wrap the bars I can free up thevslack

Fixed it for you.

I'm impressed that the OP needed anyone to point it out.

Everyone, including you, missed it. Why would a relative neophyte realize?

Sorry, it's so.

However, you shouldn't need to live with it. I see that you raised the bars by a half inch or so. Likely that was as far as the front hrake cable b allowed.

Dropping them back may be all that's needed. Certainly worth a try if you don't want to re-cable.

I missed it because I didn't see the photo, and the OP asked a very common question, thereby getting the very common answer. And of course, we're not psychic, and can't know the OP's skill level or the bike's service history. Had the OP included, "......until I raised the bars.....", we might have factored that.

Also, he might have noticed since he apparently raised the bars as far as the cable allowed, thereby creating the problem. I would hope, though maybe not expect, that if someone raises bars until he's tugging on a cable, he'd know that he's tugging on a cable.

I diagnosed it with the photo that is in the beginning of the thread. The cable is pulled tight at an angle. Everyone saw that photo.

Oh my God!!

You're a fu#$%ing genius. So much smarter than everyone here.

Now are you happy?

BTW I won't point out that you missed that the bars had been raised. Oops, I just did.

I guess you missed that I was the one that explained to the OP how to raise his bars.

I get a little tired of the amount of half-assed advice given in this subforum by people that like to tout their experience. Threads just fill up with irrelevant rabbit holes instead of basic troubleshooting, seemingly because people are more interested in sharing their personal bicycle philosophies and judging the OP instead of just asking basic questions and looking at the clues. You actually told the OP that there is nothing wrong. Redic. Other suggestions were taking everything apart, rotating the caliper or just giving up.

The OP isn't the expert you are I guess

I missed it because it wasn't on this thread, and as I pointed out, I'm not psychic.

OTOH, knowing, as you apparently did, you might have pointed out WHY his cable was now to short, and suggested he put the bars back where they originally were, thereby solving his problem.

[QUOTE=Kontact;22997346I get a little tired of the amount of half-assed advice given in this subforum by people that like to tout their experience.....[/QUOTE]

There's an irony here that you seem to miss. My original "nothing wrong with the brake...." post was specifically intended to counter all the preceeding posts of the type you hate. Essentially we agreed.

Likewise, with my post intended to reinforce yours about the short cable. However, despite two posts of basic agreement, you chose to start an argument, instead of helping the OP solve his problem.

There's the difference. I try to focus and help OPs solve their mechanical problems without causing them to do unnecessary or counterproductive work. You do so also, but cloud that with pointless argument.

By example, I could (but normally wouldn't) point out that having told the OP how to raise the bars, and knowing that the bars had been raised, you COULD have helped the OP by telling him to put them back down, but didn't (as I did 2 posts later)

I'm sorry I offended you, that wasn't the intent.

It's not about ego or bragging rights. It's about learning to think about things and connect dots.

You knew you'd raised the bars. That wasn't mentioned, and no one would have known that on their own. So yes, I do expect one who raises bars to where they were pulling on the cable might consider that as a possible cause of their problem.

Please understand, that I'm a fan of the Tao proverb about teaching fishing vs. giving fish. When here I try to offer help in a way that might help people step back, see the big picture, and hopefully get more than an immediate solution.

Also a reminder to anyone patient enough to have read this far.

Just as doctors are trained to get the whole medical history, it's helpful to give some history and context when describing a problem.

This is a perfect example. The way the problem was described, put the focus on the caliper itself, whereas more info would have helped lead to the right solution.

I think the picture makes the cable look tighter than it is and I'm not sure I even raised the bars but the tight cable may be the right answer. Again I'm hoping that when I free up the cable from the handlebars it may put less tension on the cable. The handlebar tape needs to go anyway.. Thanks for your input.

A few points.

Untaping the bar may not help, unless you retape with the cable escaping sooner. Also, while you may not have raised the bars, somebody did, as evidenced by the discolored band on the stem.

So, you might save yourself a trip down the rabbit hole by lowering the stem half an inch or so, and see if it solves the problem. If so, you can either leave it there, or go back up and do what's needed about the cable.

If dropping the bar, and slackening the cable doesn't help, you can then focus on the brake as you seek the answer.