Roller brake vs long drop dual caliper

[breakwellmz]

Apart from weight saving, will i gain braking power by replacing a Shimano Rollerbrake IM70 with a long drop (75mm) dual caliper?

Cheers.

[Brucey]

not necessarily; it depends on whether each brake is 'at the top of it's game' as it were...

cheers

[breakwellmz]

Assuming both at their best so like is being compared to like.

[Brucey]

thinking about it, in terms of stopping power I would put the roller brake ahead of the long-reach DP (although they are not all the same by any means) if it is in good shape.

You won't chuck yourself over the handlebar with it though; they have a slip clutch in the front hub which is intended prevent that.

cheers

[le.voyageur]

the roller brake will also improve your braking in the rain

[foxyrider]

From my experience the bigger breaking moment of the rim brake will at the very least make it feel better.
The Shimano long drop DP's on my 'audax' bike stop very efficiently, I have no issues with them at all.

None of the Roller brakes i've used have instilled any degree of confidence, you tend to stop somewhere within the same week! And that's on the flat.

To be fair if you ride @ 10mph on the flat they are okay but beyond that I wouldn't be happy at all. There again what i'm prepared to accept may well be different to others, if your expectations are low just stopping might be enough!

[le.voyageur]

I used a roller brake on a heavy commuter for years and never had any worries about it stopping me. As Brucey also points out they have an inbuilt mechanism to stop you going over the handlebars, I don't know if this because these brakes are aimed at casual riders (and therefore inexperienced cyclists) or if they're "so powerful" Shimano had to limit their abilities. The Shimano roller brakes need grease in the rollers and without it they become much less effective.

[breakwellmz]

Thank you all.
I`ve had experience of the earlier Nexus roller brake which if nothing else was consistent in all weathers.....always c..p!
I`m a regular modern motorcycle rider so i suppose i have pretty high standards when it comes to braking on two wheels, it`s hilly around here as well!

Cheers

[Brucey]

The Shimano long drop DP's on my 'audax' bike stop very efficiently,...

'long drop' in name only cf the ones in the OP; they are ~20mm longer than yours, I would expect....

cheers

[RJC]

Is this for a front or rear brake?

The IM70 is one of the better examples compared to roller brakes further down the scale.
The IM80 series are even bigger but not heard anyone say they are usefully improved.
My limited experience is that roller brakes are OK but it can be tricky to modulate for strong braking, hence the reason for roller brake compatible front hubs to have an anti lock mechanism.

Robin

[breakwellmz]

Both.
They seem a very complicated, expensive and heavy solution to the alternatives without a clear advantage as i see it, and a shame they came with the bike i bought! (Which was primarily for the Nexus 8 hub)

[Brucey]

...They seem a very complicated, expensive and heavy solution to the alternatives without a clear advantage as i see it....

I don't disagree. They also drag slightly, IME.

Imagine the brief that shimano's engineers were given; you have to make a brake that works (for utility purposes) as well as an integrated SA or Sachs (SRAM) hub brake, and ideally is as trouble-free as a coaster brake, but that

a) can be replaced (as a lump) in a few minutes
b) is largely maintenance free (a bit of special grease from time to time)
c) does not obstruct access to the spokes too badly
d) can be bolted onto a wide range of hubs
e) that will allow hubs to be used with either rim brakes or hub brakes
f) that (ideally) can be manufactured inexpensively using shimano's core competencies in metal-bashing
g) of a novel design that can be secured/protected by copyrights and patents

Well they did most of those things; and for someone who just wants to ride their bike a few miles each day with minimal aggro they are OK I suppose. When they wear out just bolt another one on. Quicker and cheaper than having a wheel rebuilt with a new rim (worn out with rim brakes) when it wears out, far less hassle in (typical neglectful) ownership than a disc brake.

Shame they ended up overweight, shame they ended up a bit draggy, shame it turned out that they needed to fit a slip clutch in all the front hubs (they might seize up entirely if they overheat or are run bone dry).

With a similar brief SRAM came up with the short-lived 'I-brake'; for a short while SRAM hubs were available with a four-bolt fixing on the LH side, to which the 'I-brake' could be bolted. It looked like a roller brake in appearance, but it was actually a conventional (dry) drum brake with a large-diameter drum and a narrow friction surface.



It was available in front and rear fitments. It could have been OK, but it wasn't. They could have even made it fit to a six-bolt disc brake hub, but they didn't. They even tried to make it look like a disc brake

-check out the drillings in the aluminium 'disc'....

The thing even looked half-way convincing; the reality was that the brake shoes were large and flexible, and the friction linings were very thin. The result was a brake with limited wear life, and a brake that was prone to squealing like a stuck pig, with no cure available other than brake replacement. Presumably they got a lot of returns and/or they didn't make any money out of selling them; either way they were outroduced not long after they were introduced, and anyone with a bike fitted with I-brakes effectively has a white elephant on their hands; when the brakes fail (through wear or unstoppable squealing) replacements are not available. Nothing else fits the hubs.

I guess someone clever could adapt a disc brake to fit the SRAM hubs. There are (were) also adaptors that convert the shimano roller-brake spline to a disc brake fitting; before the introduction of the Alfine series of hubs, folk wanted to use a red-band nexus 8 with a disc brake and so these were made by a few suppliers. The adaptor needs to have a cartridge bearing in it, because a disc can't be mounted well enough, directly to the roller brake spline only. Last time I checked (about eighteen months ago) there was one place where you could still buy one.

cheers

[breakwellmz]

Interesting.

[Abradable Chin]

None of the Roller brakes i've used have instilled any degree of confidence, you tend to stop somewhere within the same week!

Even worse, I find mine erratic, and I upgraded to bigger ones to try to improve it. I once sailed right through a crossroads!
In the thread about the fixie rider in court, people are saying his stopping ability was knowingly not as good as it could have been, and I wondered where this left people with chrome rims on a damp day, or people with roller brakes...

[[XAP]Bob]

I wonder where it leaves anyone with part worn tyres, or not driving something like a VX220 with ceramic brakes...