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Roller brakes: running friction?



 
 
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  #1  
Old June 25th 05, 09:33 PM
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Default Roller brakes: running friction?

Shimano says the following about their roller brakes: "Inter-M brake is
different from conventional brakes in that the inside of the brake drum
is filled with grease. This may cause the turning of the wheel to be
slightly heavier than usual, particularly in cold weather"

1. So they have running friction. Does anybody know anything more about
this?

2. They say that there should be 15 mm of play in the brake lever. That
is a lot of movement. Perhaps the gap between pad and drum needs to be
large to reduce the drag caused by the grease in the gap. Is that the
reason?

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  #4  
Old June 26th 05, 09:38 AM
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Default Roller brakes: running friction?

wrote:
Shimano says the following about their roller brakes: "Inter-M brake is
different from conventional brakes in that the inside of the brake drum
is filled with grease. This may cause the turning of the wheel to be
slightly heavier than usual, particularly in cold weather"


Having ridden on these hubs for over a year, I'm fairly happy that any
effect is minimal and maybe only psychological. If I hadn't read the
Shimano website, I would be blissfully unaware of any theoretical
slowdown in cold weather.

1. So they have running friction. Does anybody know anything more about
this?


I took the front wheel off did some comparative spinning with a
conventionally hubbed wheel. There wasn't a significant difference.

2. They say that there should be 15 mm of play in the brake lever. That
is a lot of movement. Perhaps the gap between pad and drum needs to be
large to reduce the drag caused by the grease in the gap. Is that the
reason?


As another poster observes, you don't get disc brake standard instant
stopping with hub brakes but it is more than perfectly adequate.

My only dislike about the set up is that you can't /see/ anything. I get
these paranoid moments when I become convinced the brakes are dragging
and out of adjustment. With conventional brakes, a quick glance tells me
that no, it's not the brakes, it's me that is dragging and out of
adjustment.
  #5  
Old June 26th 05, 11:00 PM
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Default Roller brakes: running friction?

Thanks for the replies. By 'play' I meant 'lever travel'. More quotes
from Shimano:

"Turn the cable adjusting bolt of the brake unit or brake lever so that
there is about 15 mm of play in the brake lever."

"The amount of movement in the inner cable must be 14.5 mm or more when
the brake lever is depressed. If it is less than 14.5 mm, braking
performance will suffer, and the brakes may fail to work."

Perhaps that last sentence indicates that:
friction - heat - reduced performance


"If you apply the front Inter-M brake strongly while the bicycle is
stopped and then shake the wheel, you will notice that there is a small
amount of play in the brakes. This is normal, and will not cause any
problems at all while riding."


"The front Inter-M brake has a built-in power modulator which controls
the braking force applied to the hub. Noise is generated by the
operation of the power modulator when the brake is applied, but this is
not a sign of a malfunction."

Curiouser and curiouser.

  #7  
Old June 27th 05, 10:47 PM
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Default Roller brakes: running friction?

Alex Rodriguez wrote:
An adequate brake should be able to lock up the wheel.


Shimano says that the power modulator (a clutch) in the brake "prevents
the wheel from locking-up if the brake force is getting too strong."

See their picture at:
http://cycle.shimano-eu.com/publish/...the_power.html

  #9  
Old June 27th 05, 10:59 PM
Clive George
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Default Roller brakes: running friction?

"Alex Rodriguez" wrote in message
...

Adquate for what? I have a Nexus 7 and I can grab the brake till it
touches
the bar and it only slows the bike down a bit. An adequate brake should
be
able to lock up the wheel.


Apply the front brake sufficiently and it will be able to :-)

Seriously, the back brake shouldn't be doing much of the slowing anyway, so
being a bit crap isn't much of a problem. Unless the front brake is also
crap.

(This does not apply to tandems :-) )

cheers,
clive



  #10  
Old June 27th 05, 11:50 PM
Pete Biggs
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Default Roller brakes: running friction?

Clive George wrote:
"Alex Rodriguez" wrote in message
...

Adquate for what? I have a Nexus 7 and I can grab the brake till it
touches
the bar and it only slows the bike down a bit. An adequate brake
should be
able to lock up the wheel.


Apply the front brake sufficiently and it will be able to :-)

Seriously, the back brake shouldn't be doing much of the slowing
anyway, so being a bit crap isn't much of a problem.


Agreed.

Unless the front brake is also crap.


Roller brakes can be used up front as well. It's one way to make you ride
extremely carefully, I suppose ;-)

~PB


 




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