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Discussion Starter · #1 ·
I recently built two sets of wheels using the Kinlin XR-200 rims. One set was for me, the other for a friend. We got a good deal from LikinBikin for $35 per rim.

The problem we are both having is brake pulse. I cleaned the rims thoroughly, and set the toe angle on the (new Cool Stop) pads. Initially, I thought it was the rim joint. There was a step at the seam so I sanded it down. The surface is smooth now, but brake pulse still exists. In fact, the brakes seem to catch closer to the valve hole, as opposed to the seam. At high speeds it's not such a problem, but at slower speeds my bike feels like it's jerking forward and back. :mad2:

Any ideas? Or is this simply a quality issue with the rims? I found some older threads with similar problems but didn't want to bring them back from the dead. I'm begining to regret going with these rims... should have stuck with the Aeroheads. :cryin:

I appreciate any help.
 

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Discussion Starter · #3 ·
I was using the stock Ultegra pads but have since changed over to Cool Stop blacks. It's only the rear wheels that have this problem. Braking is fine up front.

If there's no fix I'll probably have to deal with it. I don't want to send the rims back and rebuild....
 

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ohdee said:
At high speeds it's not such a problem, but at slower speeds my bike feels like it's jerking forward and back.
It is most likely caused by a sudden change in brake track width. It is rare, but can afflict any brand of rim... and it's very difficult to spot ahead of time even when measuring with calipers.

Most likely what is happening is that there is a small spot where the track width is narrower. When the pads pass this area they lose force on the rim then "grab" again where the rim is wider. This can be fixed by *gently* spreading the rim in the narrow area, or squeezing in slightly on either side of the narrow area to make the narrow part less abrupt.

One way to find the spot is to use a rubber band around your brake lever to provide light pressure of the pad on the rim, then spin the wheel by hand to determine where the discontinuity is.
 

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I’m guessing you have checked given that you replaced pads, set toe, etc but the only time I had problems with pulsing, I had swapped wheels and the pads were a bit too low on the new rim. The pad grabbed the non braking (non-machined) surface of the rim ever so slightly. might check.

I give this one a yuck! Good luck. Let us know what you learn.
 

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Discussion Starter · #6 ·
rruff said:
It is most likely caused by a sudden change in brake track width. It is rare, but can afflict any brand of rim... and it's very difficult to spot ahead of time even when measuring with calipers.

Most likely what is happening is that there is a small spot where the track width is narrower. When the pads pass this area they lose force on the rim then "grab" again where the rim is wider. This can be fixed by *gently* spreading the rim in the narrow area, or squeezing in slightly on either side of the narrow area to make the narrow part less abrupt.

One way to find the spot is to use a rubber band around your brake lever to provide light pressure of the pad on the rim, then spin the wheel by hand to determine where the discontinuity is.

This is what I suspect is the problem. I'd be willing to 'gently' adjust the width where the problem occurs but I'm a little worried I'd screw things up even more. Any suggestions on how to widen (or narrow) the brake track? I like the idea of using the rubber band to find the problem areas.

GH-Mike said:
I’m guessing you have checked given that you replaced pads, set toe, etc but the only time I had problems with pulsing, I had swapped wheels and the pads were a bit too low on the new rim. The pad grabbed the non braking (non-machined) surface of the rim ever so slightly. might check.
I've adjusted the pad contact area numerous times. They seem to be perfectly set. Don't think this is the problem, but thanks.
 

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This is a known issue with that rim (no all of them). I have a set that will be replaced as well. The distributor will be getting a new shipment of rims in early May (or so) with a different brake surface treatment that should address the issue.

-Eric
 

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Discussion Starter · #8 ·
I put my one of the wheels in the stand and found the spot where the brake track gets wider. I had about 1mm on each side of the rim and the gap suddenly closes (on both sides) right near the valve hole. I might try to nudge it in with some pliers and something over the teeth to protect the braking surface.

Thanks for the help everyone! :thumbsup:
 

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ohdee said:
Any suggestions on how to widen (or narrow) the brake track? I like the idea of using the rubber band to find the problem areas.
Narrowing is easiest... get a couple of flat pieces of metal, put them on either side of the area you want to squeeze (to protect the surface and spread the load a bit) and use some channel locks. To widen you'll need to push outward which is a little trickier. I used some pieces of aluminum rod on either side and a big screw driver to pry them apart.

You don't need to get it perfect... a small change will usually make a big difference.

I haven't had any problems with an XR200... but have had with one XR300, a DT1.1, and a Zipp.
 
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