Shimano Roller Brakes

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Mark Berry
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Re: Shimano Roller Brakes -- Grease

Post by Mark Berry »

Whenever I have my wheels off I shove a small dab of high melting point grease directly onto the brake rollers (which are partially visible by the hub splines). The brakes work extremely well, and have done so over a couple of years of commuting. I've never had such low maintenance brakes - wonderful! I deliberately gave the rear a severe test in descending Box Hill a couple of weeks ago, and got the cooling fin too hot to touch. There was some fade, but no grease escape or smoke. Once cool, braking returned to normal. I expect my £3.00 tin of grease to last for many years!
donse
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Re: Shimano Roller Brakes

Post by donse »

Mick F wrote:I fitter roller brakes to Barbarella some years ago and as the frame didn't have any fittings for roller brakes, I made a couple of brackets from brass strip and clamped them onto the frame. I used short lengths of inner tube to stabilise the arms and protect the paintwork.


Hi Mick, Most interesting as i am considering a similar solution for my front fork/wheel (cargo-bike, classic danish Long John).
What is your experience - does it hold out OK?
Can you possibly (please) post a couple of closeup's of your solution?
That will be greatly appreciated :)

Best regards
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Mick F
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Re: Shimano Roller Brakes

Post by Mick F »

Hi and good evening!
Welcome to the forum.

I'll see what I can do with a photograph tomorrow morning. I had some brass strip and bent it in a vice and used pliers to get it to the right shape. Took a bit of fiddling, but it works just fine.
Mick F. Cornwall
Brucey
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Re: Shimano Roller Brakes

Post by Brucey »

you can buy clips that are made for a similar purpose from Sturmey Archer for (their hub brakes). These might work and may save you a job.

[edit. e.g. http://www.sjscycles.co.uk/sturmey-archer-brake-arm-clip-5-8-inch-hcb101-prod19075/ there are other sizes too BTW ]

cheers
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Mick F
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Re: Shimano Roller Brakes

Post by Mick F »

As promised, here's my efforts on clamps. They work fine!
Front1.jpg
Front2.jpg
Rear1.jpg
Rear2.jpg
Mick F. Cornwall
fatboy
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Re: Shimano Roller Brakes

Post by fatboy »

How do these things work? I can't see from pictures etc what's inside and how they work? Anyone care to explain!
"Marriage is a wonderful invention; but then again so is the bicycle puncture repair kit." - Billy Connolly
Brucey
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Re: Shimano Roller Brakes

Post by Brucey »

There are 'brake pixies' inside it... no, really...it is basically a drum -type brake with lubricated metal on metal shoes, and roller/cam actuation;

Image

from

http://www.rideyourbike.com/shimanoIGH.shtml

there is also an official service 'manual' here

http://balisages.btwin.com/pdf/notices/elops/frein_shimano_roller_brake_elops.pdf

but really for all the explanation within it, it might as well just say 'add grease if the brake pixies scream too loudly'....

cheers
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fatboy
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Re: Shimano Roller Brakes

Post by fatboy »

Brucey wrote:There are 'brake pixies' inside it...


Thought as much! Now I see that the three metal arc pieces are brake shoes that you grease to make them work............All seems wrong!
"Marriage is a wonderful invention; but then again so is the bicycle puncture repair kit." - Billy Connolly
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Mick F
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Re: Shimano Roller Brakes

Post by Mick F »

Yes, seems wrong!

Barbarella never had her roller brakes greased in maintenance, but then she doesn't do many miles.

However, saying that, the front hub and roller brake was borrowed for use with my Raleigh Chopper. Now here's a big difference .................

Barbarella has 27" wheels and the brakes are ok but not great. I wouldn't like to use them fully loaded at speed, though she has towed my trailer full of coinage to the PO to pay in from the Poppy Appeal. Goodness knows what it weighed, but the brakes held - but only just - on our steep drive.

The performance on the Chopper's 12" front wheel was completely different. It was so good, I reckon I could have done a header - on a Chopper! - wheelies, yes, but a header??? I kept the roller brake well greased - every hundred miles or so - and that helped to take the fierceness off the braking.

I couldn't really understand the differences between 12" and 27" but it must be something to do with leverage. Basically, roller brakes work better on smaller wheels than on bigger wheels.
Mick F. Cornwall
Brucey
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Re: Shimano Roller Brakes

Post by Brucey »

a half-size wheel with the same hub brake is like having a disc brake upgrade to a disc twice the size.

Standard discs are 160mm. Seen many 320mm discs?

Imagine how powerful they would be.... :shock:

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Edwards
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Re: Shimano Roller Brakes

Post by Edwards »

Mick F wrote:I couldn't really understand the differences between 12" and 27" but it must be something to do with leverage.


I feel sure we could pry something from you although I do not think that you would pivot on your position no matter how much force was applied.
Keith Edwards
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Mick F
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Re: Shimano Roller Brakes

Post by Mick F »

Brucey wrote:a half-size wheel with the same hub brake is like having a disc brake upgrade to a disc twice the size.
Yes, I understand that, but the difference was MASSIVE - almost locking up when at high speed - 40mph or so. Quite frightening, so that's probably what the Power Modulator is for - for idiots like me putting a roller brake on a 12" wheel.

Perhaps the braking difference is exponential?
Also, a 12'' wheel spins faster, so that may make a difference.
Mick F. Cornwall
Brucey
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Re: Shimano Roller Brakes

Post by Brucey »

Mick F wrote: Perhaps the braking difference is exponential?
Also, a 12'' wheel spins faster, so that may make a difference.


-exponential? Only if the brake force is a strong variable of something else during braking, like time of application, or brake temperature. This could easily be the case, since the metal brake shoes will get very hot indeed and are not effectively cooled on long descents. Metal-on-metal friction couples very often get more 'grabby' as the temperature increases (up to a point); this property is exploited in friction welding processes.

-the small wheel size, (about half) means that not only is the brake force retarding the bike double (for any given lever pull), the work done inside the brake (force x distance x time) or (force x speed inside brake) is also doubled. If the brake is going to change with temperature, that will happen more easily with the smaller wheel.

So if you start braking harder (i.e. slowing down faster) with the smaller wheeled bike it might well feel like it is coming on stronger all by itself, because it is. This is again more likely if there there isn't enough grease inside the hub.

Shimano's torque limiting hub clutch is (I believe) to mitigate against what happens if someone uses an unmaintained brake that has no grease in it. In extremis the brake could conceivably seize up, leading to the kind of lawsuit that gives manufacturers the absolute willies.

cheers
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donse
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Re: Shimano Roller Brakes

Post by donse »

Mick F wrote:As promised, here's my efforts on clamps. They work fine!

Hi Mick, Great work - looks perfect!
Thx a lot for sharing and showing me :)

And to Brucey: Thx for pointing at the clips available from Sturmey Archer. However they are too small (even the 7/8 version) for the classic Long John-cargobike fork ends :(

So i'm off to the workshop :idea:

Best regards
Brucey
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Re: Shimano Roller Brakes

Post by Brucey »

fwiw I'd probably make my own too but if a 1" one would do then you can just buy it;

http://www.sjscycles.co.uk/sturmey-archer-brake-arm-clip-1-inch-hcb103-prod19076/

cheers
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