Everything there is to know about drum brakes

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KneesUp

Guru
After fettling with the brakes on my bike again over the weekend, they're still not that great. I know how to adjust them, I know pads make a difference and I know maintenance makes a difference. But they never seem to work perfectly for long.

They are rim brakes and so have all the inherent disadvantages of that design - braking wears the rim, wet weather makes them less effective, and if the wheel is buckled they rub. Plus it's a pain to get them to centre properly.

My bike frame as is won't take discs - it would need bracing at the back and a new fork, and nice 1" off the shelf forks with disc mounts are a little thin on the ground anyway. Besides which, I don't really like the sound of discs. I've never ridden them, but as far as I can tell from reading here, there can be issues with noisy application, with judder, with pads lasting less time than they take to fit, with discs warping, with hot discs burning people and you still get rain and muck and all sorts on the braking surface, which means that in the wet they still don't brake immediately.

So, I've been looking at drum brakes. Not the Shimano roller brakes, the drum brakes as made by Sturmey Archer. These seem to address many of the issues:

1) the pads basically last forever (I've read of 20,000 miles) and there is enough adjustment in the system to mean you don't need to unbolt the cable during the life of the pads

2) they are sealed units, so even in the wet the pad and braking surface is dry and clean

3) you can fit them to a bike without disc mounts (sturdy fork recommended - mine is)

4) there is no rim wear

5) they look neat

6) I can use 26" rims designed for discs, wich gives me a lot more choice. Many 26" rims now have no brake track.

On the minus side they are a few hundred grams heavier than a normal hub (although some of that is offset by the saved weight of the cantilever arms and possibly being able to get a lighter rim)

That's as far as I've got. I don't know anyone with drum brakes, or anyone who has ridden with them. If you have drum experience, I'd love to hear it.

The bike is my drop-bar MTB conversion with slicks, which gets used for everything really, unless it's really muddy, when I use a normal MTB, or it's a high day or holiday, when the road bike comes out.
 

mjr

Comfy armchair to one person & a plank to the next
Dutchie currently has a SA XL-FDD hub kindly given to me by a rider on here. It's working well so far, after about six months. Braking force is impressive, able to stop a lightly-loaded Dutch bike basically as fast as grip allows. There's a slight squeal in gentle braking so I think I might need to clean the drum, but that'll be the first maintenance so far.

The only thing which I think you need to be warned about is that completely linear braking feels quite strange at first: there's no increase in the braking force like when pads have cleared the water from the rim or started to warm up - if you want more braking, you have to squeeze harder.

Also, while you don't need to unbolt the cable to adjust it, you also don't need to unbolt it to remove the front wheel. There's a nifty way to unhook the brake cable - just remember to hook it back into the arm afterwards!
 
OP
OP
KneesUp

KneesUp

Guru
Any reason you don't fancy the Shimano jobs? Theyre quite good. Geoff Apps has used them on his new design.
I've read that they drag a little, and that with heat from long descents (I live on the edge of the Peak District) they can burn off the grease in them, but happy to be corrected.
 

Drago

Legendary Member
I don't know that the SA ones are better. Apps doesn't think so, having experimented with and modified the SA jobs, and as an experimenter and builder he has more experience than me, hence me suggesting the OP seeks his counsel.
 

classic33

Leg End Member
Contaminate the pads in any way and you can kiss them goodbye.

Replacements are nigh on impossible to get in this country. Ended up with a local company having to reline them.

A pair of them in use, have slowed over a quarter of ton, from over 30 to walking speed. They've also held the same weight on a 40° slope.
 

GeoffApps

Senior Member
Location
Scottish Borders
Dutchie currently has a SA XL-FDD hub kindly given to me by a rider on here. It's working well so far, after about six months. Braking force is impressive, able to stop a lightly-loaded Dutch bike basically as fast as grip allows. There's a slight squeal in gentle braking so I think I might need to clean the drum, but that'll be the first maintenance so far.

The only thing which I think you need to be warned about is that completely linear braking feels quite strange at first: there's no increase in the braking force like when pads have cleared the water from the rim or started to warm up - if you want more braking, you have to squeeze harder.

Also, while you don't need to unbolt the cable to adjust it, you also don't need to unbolt it to remove the front wheel. There's a nifty way to unhook the brake cable - just remember to hook it back into the arm afterwards!

You're quite right about the braking force; the effective braking surface is considerably larger than any rim brake. Any noise from a drum brake indicates that there is some contamination on the brake shoes; a tiny bit of grease or oil maybe. It will probably eventually disappear after several weeks, or months.

Your second paragraph is, sorry to say, completely wrong. Drum brakes operate 'concentrically' (the best word I can think of to describe it) and thus have a kind-of self-servo effect. This means that the braking force is not relative to the pressure applied to the brake lever, as is the case with rim brakes. The braking effect is relative to the position of the brake lever so that little or no force needs to be applied. Once you have pulled the brake lever to the extent to provide the amount of braking required in any one situation, the self-servo effect will maintain the braking force automatically, until you either pull more on the lever, or release it.

As to Shimano Roller Brakes, I cannot recommend them highly enough, in particular the IM80 series. The internals rely on a dose of grease to work quietly, so no problems with contamination of the brake shoes. They're relatively cheap, require virtually no maintenance and can be completely dismantled with just a small screwdriver in a matter of one or two minutes. Their principal drawback is weight, although this not inherent in the design; they could be made a lot lighter if there were a market for such a product. With a standard set-up you need to undo and remove the anchor bolt to drop the wheel from your frame. However, I have modified mine with quick-release anchor bolts. Read a bit more here

I have never encountered a problem with the brake grease burning off in this country; you need something very steep and very long before problems arise. In the Hartz Mountains once, after about three or four miles of unremitting steep, I began to notice the smell of burning grease. I stopped for a little while to enjoy the view and to let the brakes cool down a bit. This was at the beginning of the ride, and they worked fine for the rest of the day. You can buy a 'single-dose' tube of the special grease, which would be ideal to take on a ride; very easy and quick to administer, but ridiculously expensive. I have considered putting a small syringe full in my toolkit, but since that one occasion, I've not had any cause for concern.
 

mjr

Comfy armchair to one person & a plank to the next
Your second paragraph is, sorry to say, completely wrong. Drum brakes operate 'concentrically' (the best word I can think of to describe it) and thus have a kind-of self-servo effect. This means that the braking force is not relative to the pressure applied to the brake lever, as is the case with rim brakes. The braking effect is relative to the position of the brake lever so that little or no force needs to be applied. Once you have pulled the brake lever to the extent to provide the amount of braking required in any one situation, the self-servo effect will maintain the braking force automatically, until you either pull more on the lever, or release it.
So I'm completely wrong... except that I'm completely right in saying the braking force is maintained, varies only with lever pressure and doesn't increase like rim brakes do as they clear water and heat pads.

If IM80 is so good, why is there still a confusion of others in the Shimano range?

I've actually a Shimano brake in the rear hub of the Dutchie, although not a IM80. It's given me some trouble, which I suspect is the inadequate factory lubrication which Shimano seem to be criticised for on a few websites (but I hadn't noticed until it failed in use).
 
OP
OP
KneesUp

KneesUp

Guru
@GeoffApps I've just spend a very interesting hour or so reading your website. Thank you.

I presume you find the roller brakes out perform the SA drums? I think I am drawn to the SA items because you can get a cassette hub version - obviously with your internal gears this isn't relevant to you, but I tend to avoid the sort of conditions you seem to actively seek :smile: There is probably also a small element of wanting to be contrary by not using Shimano stuff, and also of having half an idea of how drums work, having just about managed to change the shoes on my first car many years ago.

It seems that hub brakes and their derivatives are perfect for most practical cycling, but they could do with better marketing and a bit more refinement. I expect it's a situation with which you are well acquainted.
 
OP
OP
KneesUp

KneesUp

Guru
Contaminate the pads in any way and you can kiss them goodbye.

Replacements are nigh on impossible to get in this country. Ended up with a local company having to reline them.

A pair of them in use, have slowed over a quarter of ton, from over 30 to walking speed. They've also held the same weight on a 40° slope.
I don't intend to open them up unless I need to, so hopefully contamination won't be an issue :smile: Do you have the 90mm or 70mm version?
 

tyred

Legendary Member
Location
Ireland
I don't have any experience of modern drum brakes but think they should be more common than they are. The Sachs ones in my Post Office bike are very effective.
 
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