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Background

Because I just cannot ask a question without a textwall of unnecessary context. This is my old bike. It's somewhere between 20 and 25 years old; the last 15 of which were spent on my balcony (dry, but outside temperature). It's seen all my teenage years, but not a professional mechanic. Lately we've started cycling in our family, so I've resurrected it. I changed the tires and the tubes (since the old ones were a lost cause), and the next part that is now giving me trouble are the brakes.

The front brakes are kinda OK-ish. When I say "cycling" I mean "slowly cruising between 10 and 20 km/h, because we have a 6 year old kid with us", so for that purpose they are fine. Although I wouldn't expect them to perform any emergency stops. Still, I guess that's just a matter of tuning so I'll just keep on twiddling them until I get them right.

The rear brakes however are so weak as to be basically negligible. And I haven't been able to do anything about it.

The actually relevant stuff

There are several things which have me stumped. Here's an overview. I've marked two points:

Full picture

At point A the wheel is pretty close to the center between the two metal frame parts, but at point B it's significantly closer to the right side (that is, closer to the camera). Since it's not centered, the left brake pad has to travel much farther than the right. This in turn means that the total distance both pads have to travel together is larger than what my brake lever can do. Hence: not enough pressure to the pads.

Unfortunately, I cannot see how to aligh the wheel along that axis. The only available adjustment is in a direction perpendicular to that which I need.

Left screw Right screw

Then we come to the brake pads themselves. The left brake pad is fine, but the right one is at a significant angle to the rim:

Brake pads

These are new brake pads, by the way, I bought those too since the old ones were really worn out and one was even bent for some reason. But how do I adjust THAT angle? There is nothing there that I can see:

Brake

I'm starting to wonder if maybe my frame is subtly bent and all this is a lost cause? Does anyone know how/if it is possible to make my rear brakes work?

P.S. I've been told this is an older type of brake system and I haven't been able to find a video/tutorial that shows how to properly adjust it. If anyone has a link, please share!

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    They look like early v-brakes to me, using cantilever pads, but I can't see all that well in these pictures. I've got a set like that on an old bike so would be able to answer that part, but you need to fix the wheel issue first. If you spin the wheel, is there any side to side wobble? Are both ends of the axle pushed into the dropouts all the way, and if you do so, is it still centred at A? (I'm wondering if the dish is wrong and someone has stopped the wheel rubbing by clamping it down on an angle)
    – Chris H
    May 31, 2020 at 16:43
  • @ChrisH - those are V-brakes, yes, logo and all. I thought it would be understandable from the pictures, sorry if it wasn't. But unlike all the videos I've seen, they have smooth studs. I also realized that the concave spacer which is visible in the last picure is on backwards for some reason... I guess I must have taken them apart years ago and put them back wrongly. With that out of the way I also realized that I can actually adjust the pad angle, and armed with that knowledge I think I made some progress. Haven't tested on the road yet though.
    – Vilx-
    May 31, 2020 at 17:16
  • @ChrisH - the wheel is a bit wobbly, yes, but not extremely so. Maybe some 1-3mm between both extremes. I do intend to try and adjust the spokes sometime later, but it doesn't seem a priority right now. As for the axle - both ends are definitely not at the end of dropouts. You can see that clearly in the second picture. This is my own doing to center it at A. I suppose I might be able to push them in further, but is there a point? Also, what's "the dish"? Also, the last person to remove the wheel was me when changing the tire recently. All alignment issues are my own fault.
    – Vilx-
    May 31, 2020 at 17:21
  • I was looking at a phone screen in the sun, so details were hard to make out. The "dish" off a wheel is its asymmetry. It's not immediately obvious but (essentially) all bikes with derailleur gears, like this one have asymmetric rear wheels, to make room for the gears. If this asymmetry is wrong, the wheel will sit to one side, or rather the rim and tyre will while the hub is correct. You could pull it back to centre at the chainstays (A) and not at the seatstays (B) by misaligning the wheels in the dropouts, but then the axle wouldn't be perpendicular to the direction of travel.
    – Chris H
    May 31, 2020 at 19:27
  • ... It's not impossible for the dropouts to be wrong, just unlikely. A bike shop could check the wheel is true and correctly dished. Buying the tools to do so is expensive for a one-off but they can be made in DIY versions, or borrowed at a bike co-op. All this is speculation though; figuring out the cause isn't as easy as it would be with the bike here
    – Chris H
    May 31, 2020 at 19:36

2 Answers 2

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It sounds like you've really done some good work! The pad material shouldn't be too soft. Soft enough that it creates good friction when pressed against the rim, but still rigid enough that it holds its shape while doing so. Keep in mind they will break in after using them for a few days or a week or too. The pads you have look like they should be just fine, although it's hard to tell from pics, but Kool Stop pads are my favorites and I know they work great, if you chose to try something different.

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  • Mine were some generic brand at a LBS. I don't even remember what they were called. I don't think they had much of a selection of these either. It does hold its shape but also... compresses a bit? I think I'll have to make a video. Like, the brake arms can still move forwards by a few mm after making contact.
    – Vilx-
    Jun 2, 2020 at 7:34
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Specific to the rear brakes being generally not as good as the front brakes, that's par for the course on any bike. The nature of brakes acting on wheels, and that you have most of your mass above the wheels, means that the rear brake unweights the tyre and it gets much easier to skid, or loose traction with the road. At the same time the front wheel gains weight so presses harder into the road.

The commonly held belief is that your front brake does 80-90% of the braking work, and the rear is there for three-ish situations.

  1. Braking on icy surface. The rear-brake here helps maintain a straight line.
  2. Braking while towing - if you have a moderately loaded trailer, then front wheel braking can induce jack-knifing.
  3. The front brake fails outright, so the rear brake is all you have left. Its better than nothing!
  4. If you're doing a lot of braking on a descent, you can alternate between the front and rear brakes to help manage the heat peaks. (really 3b
  5. Bonus reason, many jurisdictions mandate two independent brakes on bikes when used on the road.
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  • No, if I could get the rear tire to skid by just holding the rear brake I'd call it a success and my work would be done. That's as much braking power from it that I can expect. Instead the pads skid on the rim.
    – Vilx-
    Jun 2, 2020 at 11:52
  • Check that when you pull the brake lever, both pads touch down on the rim with out hanging over the edge or down below the flat part of the side of the rim. If so, Give the pads some time to break in.
    – bradly
    Jun 2, 2020 at 15:10

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