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Roller brake - loose "cooling disc"?

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Roller brake - loose "cooling disc"?

Old 02-18-10, 05:14 PM
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richardmasoner
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Roller brake - loose "cooling disc"?

I'm looking at a bicycle equipped with Shimano's Nexave roller brake. I know very little about drum brakes and have no hands on experience with these.

This brake has a "cooling disc" -- a circular heat sink.


On this bike, the cooling disc seems loose and rattle around a little. This doesn't seem normal, but it's not obvious how to tighten this disc.

Thoughts? TIA.
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Old 02-18-10, 07:11 PM
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There is no adjustment to tighten that. It's normal to have some play when you grasp it and shake it.
I've solved rattling problems with them just by greasing the rollers.
That little rubber plug you see directly behind the dropout is a grease port. Shimano says use only Nexus roller brake grease.
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Old 02-18-10, 11:23 PM
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Thanks so much, Dan. I kinda figured it's supposed to be that way but wanted to make sure.
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Old 02-19-10, 06:15 AM
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Originally Posted by Dan Burkhart View Post
There is no adjustment to tighten that. It's normal to have some play when you grasp it and shake it.
That doesn't speak too well about Shimano engineering. The ability to transfer heat will suffer significantly if it isn't a solid interface.
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Old 02-19-10, 09:38 AM
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Originally Posted by dabac View Post
That doesn't speak too well about Shimano engineering. The ability to transfer heat will suffer significantly if it isn't a solid interface.
Yeah, a heatsink that isn't in good contact is basically useless. Heatsinks are usually attached quite tightly in order to maximize the conduction. If it's so loose that it's shaking around, it's probably barely doing anything.
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Old 02-19-10, 12:05 PM
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Try rotating it. Maybe it screws on. (I've never had one apart.)
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Old 02-20-10, 04:06 AM
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yes I had to build up new bikes with those heat sinks on. Never understood why they were loose straight out of the box.
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Old 02-20-10, 04:53 AM
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perhaps the grease used for mounting motorcycle regulator/rectifiers would be better for heat transfer in just the cooling disk contact area, but applying that type of grease may not be feasible.
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