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I have ENVE 6.7's and the rear wheel gives a pulsing sensation when braking hard in the rear. The front is totally fine and the rear is fine for any braking on flat ground, but when it gets steeper and I have to press a little harder I get a pulsing sensation. Wheels are true with no visible defects to the brake track. Thoughts?
 

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Ahhh, the all too familiar and frustrating pulsating brake problem.

Try toeing in your brake pads. If that doesn't work, try toeing them out.

Do you see any wear groove in your braking surface? That could be aggravating your problem.
 

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'brifter' is f'ing stupid
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Take the tire off. Put the wheel in a truing stand. The feelers (how you tell how true/round) a wheel is will tell you whether the rim has any bulges or not that would be causing the pulsing.
 

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Take the tire off. Put the wheel in a truing stand. The feelers (how you tell how true/round) a wheel is will tell you whether the rim has any bulges or not that would be causing the pulsing.
^ this.

but if you don't have a truing stand, you can use your upside-down bike frame. i've built 7 or 8 sets of wheels this way.

i've sanded down several little bulges in aluminum rims that caused pulsing using 600 grit paper, a metal file, and/or a small sanding stone. this usally works. i used a hammer once. another time, the bulge was so bad i had to rebuild the wheel on a new rim.

it's far more important for the front rim to be free of this problem for a few reasons. often, you can get by with a little bulge in the rear rim and toe the pads accordingly.
 

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Take the tire off. Put the wheel in a truing stand. The feelers (how you tell how true/round) a wheel is will tell you whether the rim has any bulges or not that would be causing the pulsing.
This is a good idea. If you discover the rim is NOT at fault, then I have another suggestion.

Your seatstay brake bridge or the seatstays themselves are flexing under hard braking. Either reaches a limit, then snaps back, and the process repeats.

To prove which is the cause, try another wheel on the suspect bike, or try the suspect wheel on another bike.
 

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'brifter' is f'ing stupid
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Maybe you overheated the rim when braking for the homeless guy on the bike path.
 

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Thanks for the early morning LOL Cxwrench.

First spin the wheel while on the bike and see if it is true. If it is then move onto checking the brake calipers and making sure they are secure and not loose on their mounts. You didn't say what brakes you have, are the cantilever or single/dual pivot caliper style?

Reason I ask that is I was having a bad pulsing issue on my Giant Propel. Wheel was true, I changed the pads and cleaned the rim track and still bad pulsing. I even toe'd the pads, still no change. Took it to the shop and they couldn't find anything either and Giant was at a loss as well.

Being the engineer type I took the bike home and went over the brakes in detail. Found that even though the pivot mount bolt for the cantilever brake was to spec the cantilever arm was still loose. This was allowing the arm to move back and forth with the wheel under braking causing a skipping motion.

I pulled the arm off and ended up having to sand down the spacer until I got the arm to the point that there was no more slack in it once the bolt was snugged down and that the arm still pivoted as needed with no binding.

Brakes work perfect now, shared my info with the shop and Giant. Neither of them had thought about that, checked a couple other bikes with the same style brake and found others that even though the bolt was tight the cantilever arm was still loose.

Just takes time and a thinking cap to figure it out at times.
 

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Yes I agree. I have just too many bad experiences with clinchers to be ok with them. I am so glad road bikes are starting to adopt more and more disc brakes. I even like cable discs, they just always work great for me.
 

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Yes I agree. I have just too many bad experiences with clinchers to be ok with them. I am so glad road bikes are starting to adopt more and more disc brakes. I even like cable discs, they just always work great for me.

I think you are using the word "clincher" wrong. A clincher is a type of tire as opposed to a tubular. This has nothing to do with brakes.
 

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I think you are using the word "clincher" wrong. A clincher is a type of tire as opposed to a tubular. This has nothing to do with brakes.
He's probably talking about rim problems due to rim brakes getting them hot.
 

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Take the tire off. Put the wheel in a truing stand. The feelers (how you tell how true/round) a wheel is will tell you whether the rim has any bulges or not that would be causing the pulsing.
i'm not a mechanic, but just curious as to how a truing feelers can tell you if the pulsating is from a bulge on the rim vs. a rim that is out of true? I'm trying to visualize this process. I'm guessing for a rim with a bulge, on the side with the bulge touches the feelers? while a out of true rim will have the entire rim move closer to one feeler pad and at the same time farther away from the other feeler pad??
 

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'brifter' is f'ing stupid
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i'm not a mechanic, but just curious as to how a truing feelers can tell you if the pulsating is from a bulge on the rim vs. a rim that is out of true? I'm trying to visualize this process. I'm guessing for a rim with a bulge, on the side with the bulge touches the feelers? while a out of true rim will have the entire rim move closer to one feeler pad and at the same time farther away from the other feeler pad??
Exactly. Just like if you measured the width of the rim w/ calipers but you don't a numerical measurement. You can always confirm w/ calipers if needed.
 

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sucks when you're truing the wheel in the frame, and you don't realize it's a bulge, thinking it's just an out of true rim. you end up chasing the rim one way, then the other, before catching on.
 
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