I have a Sub-9 disc (tubular) and I’m using Zipp’s carbon brake pads. I’m getting ready for my first race on the wheel and in my first couple of test rides I’ve been really bothered by terrible pulsing or modulation or whatever you want to call it when braking. The wheel seems to be perfectly true. I’ve checked for any glue on the brake track and haven’t found any, but I’ve cleaned and re-cleaned it (acetone) just to make sure. I’ve swapped the brake pads from front to rear to see if maybe there was some wierd pad issue. Nothing has eliminated the problem.
Anyone have any ideas or suggestions? It’s bad enough that it’s almost caused me to lose control of the bike a couple of times when trying to shed speed going into turns.
Thanks,
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Check your brake pad toe-in. A perfectly flat brake pad against the wheel usually results in a pulsation.
– Boris
I am rainc this weekend on a Sub-9 as well at SuperSEAL. I notice only the slightest pulsation of the brake through the rim. This is due to the (normal) variations in rim shape at the outer, hollow circumference of the disk. Remember, there is only structural foam inside the Sub 9 down on the flat portion, there is no foam inside the bulged, lenticular secition. This is one of the things that gives the wheel nice ride characteristics.
Waddya need brakes for? It’s a triathlon! Leave those things to the roadies…
My Zipp disc does the same thing, for what it’s worth.
I have a set of Hed3C’s that do it too
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have you tried roughing up the brake pads?
Waddya need brakes for? It’s a triathlon! Leave those things to the roadies…
I find that most officials frown on it when you come flying across the timing mat and into the transition area at 28 mph and yelling for people to get out of the d#@! way.
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I notice only the slightest pulsation of the brake through the rim. This is due to the (normal) variations in rim shape at the outer, hollow circumference of the disk.
About an hour ago I had the bike in the stand and was slowly spinning the rear wheel with very light brake pressure to see if I could figure out what was going on. This is exactly the conclusion I came to. Bummer. It’s not insignificant with my wheel. On a more technical course, this will be a problem when I need to shed a little speed for a turn. The thing grabs quite hard.
Maybe I’ll get used to it when I’ve got a few more miles on it (though I’ve got about 100 now and it’s still bugging me.)
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