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One of our bikes is an electric bike. It's an older iZip HG 1000, and although we got it through the American "manufacturer" (Currie Technologies), like most of the low-end ebikes it's made in China of heavy steel and uses cheap, cheap, cheap components.

The rear brake is called a belt brake or band brake. When I was researching this a bit, I came across a discussion that said this type of brake is something like 20 cents cheaper than V-Brakes to manufacture in bulk, which is why it shows up on this type of bike.

Here's a couple pics: just the brake and then one mounted on a bike (not our bike):

belt brake belt brake on bike

Actually, now that I look closely at the pictures, I can see part of why it's cheap - no special frame fittings needed. The donut-shaped "drum" mounts to the hub, the other piece just fits over that drum and is clamped to the seat stay.

My problem is that the thing squeals like a banshee. There's no pad adjustment as there would be for cantilevers, the only adjustment is how tight the belt starts. If I loosen it enough to stop the squealing, there's not enough pull to actually stop the bike.

Is there any adjustment I could do to get rid of the squealing?

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They might have used a drum for a reason. Where is the electric motor? If it's powering the rear axle then you probably want a drum vs rim brake to avoid overstressing the spokes when braking against the motor. –  Daniel R Hicks Mar 9 '12 at 23:30
    
It's a hub brake, but like most ebikes, there are switches in the brake levers that cut power when you apply any brakes. –  Ward Mar 10 '12 at 7:07
    
Where is the motor? Chain drive on the rear or front hub? (While there may be a switch to cut power, safety would require that the brake be able to stop the bike if the switch failed.) –  Daniel R Hicks Mar 10 '12 at 12:29
    
And keep in mind that it's not unusual for bike brakes (of any design) to squeal while braking. Only if the brake makes noise when not applied is there a real problem. –  Daniel R Hicks Mar 10 '12 at 12:34
    
Note that there is that screw adjustment on the top of the brake. Not clear exactly what it adjusts -- likely how far the brake retracts when released. –  Daniel R Hicks Mar 10 '12 at 12:43

4 Answers 4

up vote 4 down vote accepted

That style of drum brake relies on friction between steel and leather. If it is setup to stop reasonably well, they will always make some noise. Quite often, when new, they do indeed howl like Baoine Sidhe.

This will get better with use. From the photos, it appears your brakes are fairly new? Assuming that they are actual photos of your bike...

Rubbing talcum powder into the leather strap will help quiet the brake, but it may also have an adverse effect on your braking performance. Best to let it work out naturally, with time and use.

I hope that helps.

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No, that's not a picture of my bike, mine is not nearly so clean. I'm working on another question (how can I retrofit some other type of brake) that will have a pic or two. –  Ward Mar 9 '12 at 21:14
    
@Ward -- Looking at the picture in your link, the only brake you could likely retrofit would be a disk brake. (And that's probably 50-50 at best, and expensive.) There's maybe a vague chance you'd be able to fit some sort of rim brake near the chain stays (after considerable disassembly), but the other members radiating from the real axle are too flimsy to support the brakes. –  Daniel R Hicks Mar 10 '12 at 12:42
    
Disc brakes aren't a practical option either, mostly due to cost factors. You'd need to replace wheels, and get a frame mount for the brake somehow, which isn't likely, and won't be cheap even if you find someone to weld it up. Honestly, ride it a while, and see if it gets better. Maybe sand the polish off the leather strap to see if it quiets down. But mostly, look for a higher quality bike, if it bothers you enough to warrant that... –  zenbike Mar 10 '12 at 14:36

The type of band-brake you have is manufactured in China. Hundreds of millions are manufactured and used effectively worldwide on numerous bicycles.

Your model of band-brake has 3 common causes for noise.

1)The spacing of brake-drum and belt-housing is too close. This can be caused by the wrong thickness of spacing washer being installed on the axle causing the outer edge of the drum rubbing on the inside of the band-housing. This situation can be easily detected by wear marks on the inside of the band-housing when disassembled. 2)The chain stay mounting or brake cable mounting is out of alignment and causing the the same effect between the drum and and band-housing.
3)The band itself is off centre when in the released position. This sounds like your problem, as you indicate that when you loosen the brake adjustment, the noise stops. The two screws on the outer edge of the band-housing adjusts this. You need to loosen the lock nuts on each adjusting-screw and adjust each screw inward or outward to provide a uniform gap between band and drum. Happy biking.

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If there are no V-brake stanchions it is possible to retrofit V-brakes if you use an adapter (you can search for these on Google).

The adapters are normally intended for BMX bikes but I have successfully used on on the rear for a bamboo bike I built.

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I have no experience with this drum set up but with similar industrial applications centering the brake band is critical.I would measure from the inner brake surface to the inside of the housing.Do this at several points.If it is off center one side makes contact and the otherside vibrates causeing the noise.Cleaning of the drum surface is important,try alcohol.If the brake material is leather Idont know what to clean it with.If it an organic material sand lightly with medium sand paper.

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This brake uses a leather strap, which is fixed on one end, and which is tensioned from the opposite end with a lever to apply braking force. It will necessarily be inconsistently spaced from the brake housing. –  zenbike Mar 10 '12 at 4:56

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