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Shimano front roller brake performing poorly (BR-IM45-F) - causes?

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Shimano front roller brake performing poorly (BR-IM45-F) - causes?

Old 11-06-20, 10:34 PM
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cudak888 
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Shimano front roller brake performing poorly (BR-IM45-F) - causes?

I'm currently working with a pair of high-mileage Shimano BR-IM45-F front roller brakes. They're exceptionally spongy and feel like a pair of Wal-Mart stamped steel sidepulls (without the slop) - even at easy 10-12mph neighborhood cruising speeds. I know the Shimano roller - especially in front - is a fairly crappy design in comparison to discs, but they're what the bikes have, I don't want to change them (I have my reasons for keeping these bikes as they are - my sig should be a clue) - and that'd be the easy way out anyway .

This said, I've experimented with the cable sensibly adjusted and ultra tight - no difference. Despite their use, they appear well-kept and don't have any externally visible wear (as expected), and are both connected to identical, unremarkable Tektro CL530-AC levers. They seemed to be properly greased when I first got them, but I went ahead and gave one of them a bit of the factory Shimano grease that they use. No difference.

By comparison, I have one bike with the slightly larger (Larger in heatsink only? Not sure) BR-6000-F, and the braking action is nothing like these BR-IM45's. Granted, the brake feel is typical for a Shimano roller - non-linear and a bit mushy - but I can confidently apply the brakes whenever I wish, knowing I'll come to a stop where I want to, and not an inch further. The BR-IM45? Better be ready in advance.

Before I fart around with them any more, should I bother? Or should I get the current BR-C3000-F (which appears to be nothing more than the BR-IM45-F with Nexus branding on it) and put the IM45's in the dead pile?



-Kurt
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Old 11-07-20, 05:34 AM
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I have a few high milage rollerbrakes of similar models. In my experience there isn't much you can do once they turns spongy. I have tried completely cleaning them, and greasing them with new rollerbrake grease, but it didn't help. However, they will still stop you, but not as confidently as they once would.

When getting higher end rollerbrakes it isnt only the heatsink that changes size. The higher end models like the 6000 have V shaped braketracks and V shaped brake shoes, which gives them better performance than the lower-end models with flat tracks and shoes.

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Old 11-07-20, 06:51 PM
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Arenít CL530 levers long pull and you want short pull for roller brakes? Iím not exactly sure of either of those statements but thatís what I Ďm remembering
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Old 11-08-20, 09:18 AM
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Originally Posted by Pyramiden View Post
I have a few high milage rollerbrakes of similar models. In my experience there isn't much you can do once they turns spongy. I have tried completely cleaning them, and greasing them with new rollerbrake grease, but it didn't help. However, they will still stop you, but not as confidently as they once would.

When getting higher end rollerbrakes it isnt only the heatsink that changes size. The higher end models like the 6000 have V shaped braketracks and V shaped brake shoes, which gives them better performance than the lower-end models with flat tracks and shoes.
That adds up. There's very little confidence to be had in the ones I have here, so replacement time it is.

It is tempting to shove in a 6000, as there's a seller with these for $40 right now - they're usually in the $60 range. It's also just $5 more than the comparable 3000 series. Seems like a win-win.

Originally Posted by AeroGut View Post
Aren’t CL530 levers long pull and you want short pull for roller brakes? I’m not exactly sure of either of those statements but that’s what I ‘m remembering
Mine are the CL530-RS AC and the CL535C-RT, respectively. Roller-brake/canti compatible: https://www.tektro.com/products.php?p=81

The casting mark for linear pull is there, but not drilled. The pivot for the cable end is in the proper location.

-Kurt
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Old 11-08-20, 12:19 PM
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It did a test ride with those on a Simcoe I really liked. They stopped well, but the crunchy grinding sound and feel is grotesque. IMO.
Imagine doing that at 40 mph on a hill. NO thanks.
OTOH... My SA XL-FDD has done 26,000 miles, including 8,100 on tour, and will likely do that again. One bearing change, otherwise all I do is have a look once a year and rough up the glaze a bit. They are basically self cleaning. The dirt just gets grinded up and falls out. Plus it's silent with NO drag.

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Old 11-09-20, 03:02 AM
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Did you grease them well? Pop that dust cover and see what the pressure band is like. Put about that much grease in them.

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Old 11-09-20, 03:30 AM
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Originally Posted by Pyramiden View Post
I have a few high milage rollerbrakes of similar models. In my experience there isn't much you can do once they turns spongy. I have tried completely cleaning them, and greasing them with new rollerbrake grease, but it didn't help. However, they will still stop you, but not as confidently as they once would.

When getting higher end rollerbrakes it isnt only the heatsink that changes size. The higher end models like the 6000 have V shaped braketracks and V shaped brake shoes, which gives them better performance than the lower-end models with flat tracks and shoes.
Yup, once they have too many miles on them there's very little you can do. Even the higher end 6000's turn mushy after enough miles. I have a bike that I did well over 40,000 km (25,000 miles) on and where I swapped the brakes out for the higher end model after a few years. By the end even those started to turn mushy and would barely stop the bike anymore. When I tried cleaning them the brakes fell apart and I just didn't bother cleaning them up anymore and tossed them.

Originally Posted by GamblerGORD53 View Post
It did a test ride with those on a Simcoe I really liked. They stopped well, but the crunchy grinding sound and feel is grotesque. IMO.
Imagine doing that at 40 mph on a hill. NO thanks.
OTOH... My SA XL-FDD has done 26,000 miles, including 8,100 on tour, and will likely do that again. One bearing change, otherwise all I do is have a look once a year and rough up the glaze a bit. They are basically self cleaning. The dirt just gets grinded up and falls out. Plus it's silent with NO drag.
I think I have done those kinds of speeds on a hill once in the Belgian Ardennes, when they were new. It was lots of fun.

But like you said, seeing how much bite the 90mm Sturmey Archer drum brakes have I'm not sure I ever want to go back anymore.
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Old 11-10-20, 09:27 PM
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Originally Posted by GamblerGORD53 View Post
It did a test ride with those on a Simcoe I really liked. They stopped well, but the crunchy grinding sound and feel is grotesque. IMO.
Imagine doing that at 40 mph on a hill. NO thanks.

OTOH... My SA XL-FDD has done 26,000 miles, including 8,100 on tour, and will likely do that again. One bearing change, otherwise all I do is have a look once a year and rough up the glaze a bit. They are basically self cleaning. The dirt just gets grinded up and falls out. Plus it's silent with NO drag.
It doesn't sound as crunchy as it sounds metal-on-metal, even when greased. Makes you think of one wheel of a freight train going through a curve.

I've run the smaller Sturmey drum front hub. It's pretty nice - not as linear as a good set of dual pivots, but improved over the original drums from the '30s through the '80s. I've also used the RXL-RD3 in the rear - no complaints there, even though they're a bit spongier, and downright strange when paired with the 6000-series roller in front.

Originally Posted by bwilli88 View Post
Did you grease them well? Pop that dust cover and see what the pressure band is like. Put about that much grease in them.
I haven't looked under the dust cover, but I can guarantee that I overgreased one of the two.

Originally Posted by JaccoW View Post
Yup, once they have too many miles on them there's very little you can do. Even the higher end 6000's turn mushy after enough miles. I have a bike that I did well over 40,000 km (25,000 miles) on and where I swapped the brakes out for the higher end model after a few years. By the end even those started to turn mushy and would barely stop the bike anymore. When I tried cleaning them the brakes fell apart and I just didn't bother cleaning them up anymore and tossed them.

I think I have done those kinds of speeds on a hill once in the Belgian Ardennes, when they were new. It was lots of fun.

But like you said, seeing how much bite the 90mm Sturmey Archer drum brakes have I'm not sure I ever want to go back anymore.
Well, there's nobody I'd figure to know best than someone who's basically surrounded by roller brakes. Had I known you ran some sets into the ground as you describe, I would have gone straight to you with my question

I'm on flat land, so 40mph downhill on a Social Bicycles 3.0 isn't happening. Not that I wouldn't try it though; they're very stable in the handling department.

-Kurt
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