pulsing front brakes?
#1
Junior Member
Thread Starter
pulsing front brakes?
Hello all.
I just started riding again after a long while. I am pretty good at maintenance and the bike is working great. After a few rides I cleaned up my Zipp 404's that are around 14 years old.
After putting them on the bike i am getting a very pronounced pulsing in just the front brake. The wheels are in great shape, they are true, and never did this before. The only thing I did was wash the bike and the wheels. When I put my other wheels back on I do not have the problem. There are black marks from the brakes on the wheels but no more so then other wheels. When I run my fingers around the rims they are completely smooth.
Any thoughts on what might cause this would be greatly appreciated.
Thanks in advance, Rich
I just started riding again after a long while. I am pretty good at maintenance and the bike is working great. After a few rides I cleaned up my Zipp 404's that are around 14 years old.
After putting them on the bike i am getting a very pronounced pulsing in just the front brake. The wheels are in great shape, they are true, and never did this before. The only thing I did was wash the bike and the wheels. When I put my other wheels back on I do not have the problem. There are black marks from the brakes on the wheels but no more so then other wheels. When I run my fingers around the rims they are completely smooth.
Any thoughts on what might cause this would be greatly appreciated.
Thanks in advance, Rich
#2
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Hit the wheels with some rubbing alcohol and LIGHTLY touch with a scotch bright pad.
The black marks from the pads changes the friction coefficient and makes the brakes pulse. My guess is that the black mark is hiding an "unsmooth" spot.
If that's not the case, make sure the brakes are toed in correctly.
The black marks from the pads changes the friction coefficient and makes the brakes pulse. My guess is that the black mark is hiding an "unsmooth" spot.
If that's not the case, make sure the brakes are toed in correctly.
#5
Senior Member
Works for me:
SandFlex Flexible Abrasive Block, Fine Grit, 3" x 2" x 3/4" followed by Alcohol wipe on braking surface. Abrasive block keeps rim surface flat. Use coarse file to knock "shine" off brake pads.
SandFlex Flexible Abrasive Blocks - Rockler Woodworking Tools
SandFlex Flexible Abrasive Block, Fine Grit, 3" x 2" x 3/4" followed by Alcohol wipe on braking surface. Abrasive block keeps rim surface flat. Use coarse file to knock "shine" off brake pads.
SandFlex Flexible Abrasive Blocks - Rockler Woodworking Tools
#6
Banned
start by replacing the brake pads..
FWIW , I fitted very abrasive pads* and did a few steepish down hill rainy stops , and wore thru a Mavic Hard anodized Brake track ,
to the base aluminum, Then replaced the pads with a more rim friendly compound .. Kool Stop .. the braking has been fine ever since.
* In my specific case it was Magura's rim brakes .. They have Kool Stop Molding their pads , then shipped them to Germany ,
now KS has the complete product.. as does the MFG..
I assume you have a road brake.. there are rather abrasive pad inserts made.. to do similar..
FWIW , I fitted very abrasive pads* and did a few steepish down hill rainy stops , and wore thru a Mavic Hard anodized Brake track ,
to the base aluminum, Then replaced the pads with a more rim friendly compound .. Kool Stop .. the braking has been fine ever since.
* In my specific case it was Magura's rim brakes .. They have Kool Stop Molding their pads , then shipped them to Germany ,
now KS has the complete product.. as does the MFG..
I assume you have a road brake.. there are rather abrasive pad inserts made.. to do similar..
Last edited by fietsbob; 10-08-15 at 10:48 AM.
#7
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I would start with cleaning the rims like mentioned above and maybe a light sanding on your brake pads. It is less likely but an extremely worn out rim can cause pulsing if the brake track has worn so thin it is causing the rim to bulge in spots. That would also mean your rim is beyond the point where you should have replaced it. Usually with lighter weight rims, after you have worn .5mm or so off the brake track they are due for replacement. You would also notice the brake track feels very concave.
#8
Junior Member
Thread Starter
Thanks for all the quick replies.
Chris, I never really used those wheels that much so I don't think they are worn.
I just tried rubbing alcohol and scotch bright. It is better but there is still some pulsing. The pads work well with the other wheels but I will try that next.
One other question specific to those wheels if I may.
I am having a very hard time mounting tires to these wheels. As careful as I am I just damaged a new tube. It almost seems like I am on the verge of ripping the tire, that is how hard it is to mount them. The tires are Vittoria Tecno pro, if that makes a difference. I have never had a problem mounting other tires and wheels.
Any tips or info would be greatly appreciated.
Thanks again, Rich
Chris, I never really used those wheels that much so I don't think they are worn.
I just tried rubbing alcohol and scotch bright. It is better but there is still some pulsing. The pads work well with the other wheels but I will try that next.
One other question specific to those wheels if I may.
I am having a very hard time mounting tires to these wheels. As careful as I am I just damaged a new tube. It almost seems like I am on the verge of ripping the tire, that is how hard it is to mount them. The tires are Vittoria Tecno pro, if that makes a difference. I have never had a problem mounting other tires and wheels.
Any tips or info would be greatly appreciated.
Thanks again, Rich
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Thanks for all the quick replies.
Chris, I never really used those wheels that much so I don't think they are worn.
I just tried rubbing alcohol and scotch bright. It is better but there is still some pulsing. The pads work well with the other wheels but I will try that next.
One other question specific to those wheels if I may.
I am having a very hard time mounting tires to these wheels. As careful as I am I just damaged a new tube. It almost seems like I am on the verge of ripping the tire, that is how hard it is to mount them. The tires are Vittoria Tecno pro, if that makes a difference. I have never had a problem mounting other tires and wheels.
Any tips or info would be greatly appreciated.
Thanks again, Rich
Chris, I never really used those wheels that much so I don't think they are worn.
I just tried rubbing alcohol and scotch bright. It is better but there is still some pulsing. The pads work well with the other wheels but I will try that next.
One other question specific to those wheels if I may.
I am having a very hard time mounting tires to these wheels. As careful as I am I just damaged a new tube. It almost seems like I am on the verge of ripping the tire, that is how hard it is to mount them. The tires are Vittoria Tecno pro, if that makes a difference. I have never had a problem mounting other tires and wheels.
Any tips or info would be greatly appreciated.
Thanks again, Rich
It does indeed make a difference for the tires. Your specific tires have a kevlar bead which is VERY tough. It makes the tires very hard to mount. There are lots of videos on how to mount those types of tires more easily on youtube.
This one shows a MTN tire but the procedure is the same regardless.
https://www.youtube.com/watch?v=zkIr...annel=MadeGood
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If you resort to using a tire bead jack you will need to have it with you when you ride, or risk getting stuck with an un-mountable tire if you should get a flat.
#11
Junior Member
Thread Starter
So the problem is caused more by the tires then the wheels. That is good to know.
I understand about getting the bead to the center of the rim, I do have the thicker rim tape as I was concerned about getting flats caused by the wheels. For whatever reason I do get more flats when riding these wheels and tires.
I just looked at the bead jack and ordered one. I only ride these wheels when my wife is available to pick me up. I could never fix a flat with this wheel/tire combo on the side of the road anyway so at least it will help me at home.
Thanks again to all that replied, I have learned a lot.
Rich
I understand about getting the bead to the center of the rim, I do have the thicker rim tape as I was concerned about getting flats caused by the wheels. For whatever reason I do get more flats when riding these wheels and tires.
I just looked at the bead jack and ordered one. I only ride these wheels when my wife is available to pick me up. I could never fix a flat with this wheel/tire combo on the side of the road anyway so at least it will help me at home.
Thanks again to all that replied, I have learned a lot.
Rich
#12
Junior Member
Thread Starter
dsbrantjr, thanks for the bead jack info.
I just used it and mounted the tire without any issues.
Rich
I just used it and mounted the tire without any issues.
Rich