Who knows owt about roller brakes?

[mickle]

My bakfiets came with an pair of Shi**no Inter M (IM40/1) hub brake. The rear is poor but the front is truly pathetic. Little power and zero feel. Maximum power comes after about twenty mm of pull of the original (and correct) lever - and then it goes all the way to the bar. I have the option of retro fitting a V brake mounting plate but it adds complexity, cost and weight when all I want is the existing brake to work. I tried a different, used but otherwise identical IM40 front and replaced the cable. There was no discernible change.

I've recently discovered that these brakes have Shi**no's notorious power modulator (it certainly feels like one). Which I understand in this system is a kind of slippingclutch mechanism. An expert in these matters has suggested a more up date IM80. But if the clutch is, as I suspect, within the hub rather than the brake mechanism the most up to date, most powerful brake in the universe wont make any difference.

Others claim that these brakes perform faultlessly on cargo bikes. WtF is going on? I have no desire to replace the hub - which seems to me to be the only option if I want it to work. The V brake plate is a last resort.

Will a new (£40+) IM80 fix the problem? If the power modulator is within the hub is it possible to disable it?

Any ideas - before I crash into something?

I'm tempted to dismantle it....

 

[RecordAceFromNew]

My bakfiets came with an pair of Shi**no Inter M (IM40/1) hub brake. The rear is poor but the front is truly pathetic. Little power and zero feel. Maximum power comes after about twenty mm of pull of the original (and correct) lever - and then it goes all the way to the bar. I have the option of retro fitting a V brake mounting plate but it adds complexity, cost and weight when all I want is the existing brake to work. I tried a different, used but otherwise identical IM40 front and replaced the cable. There was no discernible change.

I've recently discovered that these brakes have Shi**no's notorious power modulator (it certainly feels like one). Which I understand in this system is a kind of slippingclutch mechanism. An expert in these matters has suggested a more up date IM80. But if the clutch is, as I suspect, within the hub rather than the brake mechanism the most up to date, most powerful brake in the universe wont make any difference.

Others claim that these brakes perform faultlessly on cargo bikes. WtF is going on? I have no desire to replace the hub - which seems to me to be the only option if I want it to work. The V brake plate is a last resort.

Will a new (£40+) IM80 fix the problem? If the power modulator is within the hub is it possible to disable it?

Any ideas - before I crash into something?

I'm tempted to dismantle it....

To avoid any premature ending of Mickle's Tip of the Day fwiw my 2 cents are:

Afaik only the front ones can have this clutch mechanism.

It might be worth checking which specific brake model you have (this is an old table).

Finally I presume your levers are not V brake levers, or are set at the V brake setting?

 

[mickle]

Blah blah blah .... this clutch mechanism .... blah blah blah etc

That's the answer right there. The clutch is in the hub.

Bugger.

Which means fitting a spanking new IM80 will have no effect since the clutch in the hub puts a cap on brake torque. So if I want to improve the front braking the options are:

* Retro fit a V brake

* Fit a new hub

* Open up the hub to investigate the possibility of disabling or adjusting the clutch.


What a pain in the harse.

And just when I was starting to waver in my hatred of Shi**no.

 

[4F]

what you need is to give it a twack with a hammer, not one of your cheap hammers from the market mind. Only buy expensive tools

Shitmano, you should have known better.

 

[Rohloff_Brompton_Rider]

if they work on the same principle as industrial drive clutches (actually used as over torque protection), and they do look similar from the very limited drawing, then you should be able to alter the pressure at which the balls slip. in industrial ones i've worked on the past, the shorter the spring the greater the pressure, i.e., turn the lock nut assembly, either cw or ccw depending on thread direction.

again it's just a guesstimate from experience and the limited drawing.

cheers

 

[mickle]

So. The reason that roller brakes have the dirty great cooling fins on them is not to disipate the heat generated by brake friction but to disipate the heat of the power modulator's clutch slipping.

 

[RecordAceFromNew]

So. The reason that roller brakes have the dirty great cooling fins on them is not to disipate the heat generated by brake friction but to disipate the heat of the power modulator's clutch slipping.

Nope you have got it the wrong way round - the slower you stop the lower the rate of energy/heat dissipation due to friction - so to be accurate, the clutch is Sh*mano's devious way not to give you an EVEN BIGGER heat sink!

 

[fossyant]

Stick your feet down, or drag it along the tyre - you'll be fine - seems to work for loads of folk.

 

[mickle]

Nope you have got it the wrong way round - the slower you stop the lower the rate of energy/heat dissipation due to friction - so to be accurate, the clutch is Sh*mano's devious way not to give you an EVEN BIGGER heat sink!

Basterds.

 

[GrumpyGregry]

are we sure the hubs are packed with grease. are the levers set up correctly. I had some a few years back, on a Trek ATB. useless, took 'em to Brixton Bikes and they just filled em with grease and moved the pivot point in the lever. naughty naughty Trek/Evans.

Eyeball popping after that

EDIT But this was on a Nexus dynohub which iirc did not have a power modulator.

 

[Mr_colostomy]

I wouldn't bother with retro-fitting V brakes (although I do have an irrational hatred of them). Best bet is to find a hub without the modulator, or failing that, build up a fresh front wheel using a Sturmey XL-FDD drum dynamo hub. You'll probably be able to get some of the cash back by selling the original wheel/brake set-up.

 

[mickle]

I wouldn't bother with retro-fitting V brakes (although I do have an irrational hatred of them). Best bet is to find a hub without the modulator, or failing that, build up a fresh front wheel using a Sturmey XL-FDD drum dynamo hub. You'll probably be able to get some of the cash back by selling the original wheel/brake set-up.

I was hoping to avoid rebuilding the wheel TBH. Though I do really like the idea of the SA hub....