yeah, so i can't figure what is wrong. i have set up many many many brakes and never had a problem dialing things in. everything is tight (headset, qr skewers, brake pad shoe bolts, etc...) pads are lined up well, toed-in, etc...
took a look at where it pulsed on the rim, no irregularities that i can see...
took a straight edge to it, couldn't tell myself if there was any problems. it looks true on the brake pad test.
i imagine my fork is stiff enough - it is a 2016 supersix evo hi-mod - so i can't imagine that being the problem...
fairwheel's webstore is closed on weekends so i will have to wait until monday to call.
in the meantime, alloy clinchers will go back on.
Brake Pulse on Carbon Rims
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Doesn’t sound like you’re really missing anything. The rims were brand new, right? Oh, and the fork test was for @Alexandrumarian and his Boras. Got him intertwined with you. I’d check with Fairwheel like you’re going to.
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
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Unlinked Builds (searchable): Colnago C59 - 5 Years Later; Trek Emonda SL Campagnolo SR; Special Colnago EPQ
yeah, no worries.
and yep, rims are brand new.
that being said-- they might not be as true as i thought.
the first "true" test i did was a quick eye test of the distance between the rim and the brake pads as the wheel is spinning. i decided to go back through and re-check, this time removing a pad from one side and then adjust in so the pad was almost touching the rim. i spun the rim and listened for friction. once i heard friction i held the wheel and turned it slowly to check if it was, indeed touching... i did this front and rear and the rims rub the pads in many spots. unfortunately i don't have a truing stand so this is all the more technical i can get, but they do appear to be a fraction out of true. though, surprisingly, the rear seems worse than the front.... even though the front pulses more severely.
would a tiny bit of out of true be enough to cause it to pulse? someone said that 0.1mm would be enough.
again, i unfortunately don't have a truing stand, but the rims rub and would appear to be out true...
Last edited by octave on Sat Jul 27, 2019 6:07 pm, edited 1 time in total.
I had pulsing on my Farsports rims when I first got them. They were my first carbon rims so I set up the pads the same way I always have. After resetting the pads with much much less toe-in - like almost zero I had no pulsing and good braking.
So I'd try setting up the pads again, maybe with little to zero toe-in and see how they work. Good luck!
I'm using Campagnolo red pads BTW.
AJS914 wrote:I had pulsing on my Farsports rims when I first got them. They were my first carbon rims so I set up the pads the same way I always have. After resetting the pads with much much less toe-in - like almost zero I had no pulsing and good braking.
So I'd try setting up the pads again, maybe with little to zero toe-in and see how they work. Good luck!
I'm using Campagnolo red pads BTW.
no luck with this, either... still pulses.
i tried the front wheel on my other bike with Ultegra r8000 calipers and the Swisstop Black Prince pads. still no luck. pulsing.
i am going to give up for the weekend and call Fairwheel on monday...
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Alexandrumarian
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- Joined: Mon Mar 28, 2016 6:34 pm
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I don't really believe in the out of true thing. My Boras are really really true. Actually one of my rears is a bit out of whack now after being in an accident. I retrued it some but its nowhere near perfect. It still shows no pulsing or shuderring. Problem is there might be diferent phenomena we lump together in the same pot over the internet. What I experience with my fronts could be more precisely described as a high frequency stutter. Gives me a bit of handlebar trembling when I try to suddently bring the bike to a full stop. Perhaps the rears don't do this since they are more loaded by the rider plus the rear traingle being stiffer than a fork. We should try to do some braking while standing (hopefully without face planting)
Is your headset snug with no play?
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
Unlinked Builds (searchable): Colnago C59 - 5 Years Later; Trek Emonda SL Campagnolo SR; Special Colnago EPQ
Unlinked Builds (searchable): Colnago C59 - 5 Years Later; Trek Emonda SL Campagnolo SR; Special Colnago EPQ
yeah i was thinking that the front might be more severe because it bears less weight.
that being said the sensation i am experiencing is definitely a pulsing. there is strong braking, then the power drops drastically, then it grabs strongly. (almost feels like that sensation when you first grab your brakes in the rain and there is little to no power while the pads clear the water off then a big bite as they get onto drier rim)
whatever the case it is not even close to good.
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that being said the sensation i am experiencing is definitely a pulsing. there is strong braking, then the power drops drastically, then it grabs strongly. (almost feels like that sensation when you first grab your brakes in the rain and there is little to no power while the pads clear the water off then a big bite as they get onto drier rim)
whatever the case it is not even close to good.
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I’ve never used the Black Prince pads. Just the Swisstop Yellows... worst pads ever but maybe the Yellows now are different than when I had them years ago. But if it was pads I’d expect just kind of more of a uniform braking, be it poor to great and everything in between, but uniform. Pulsing is really something to do with certain spots in the rim that are causing the pads to be more grabby there. A sudden out of trueness certainly does that. A bulge in the brake track could cause it. But those are things you can see. Sounds like your issue can’t be detected visually so I’m inclined to think maybe it’s a resin/carbon mix issue which isn’t quite uniform around the entire brake track. I think I’d just get them to give you a new rim if possible and hope it’s not a problem inherent to those wheels in general. Oh and 0.1mm our of true isn’t enough in my opinion to cause the grabbiness.
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
Unlinked Builds (searchable): Colnago C59 - 5 Years Later; Trek Emonda SL Campagnolo SR; Special Colnago EPQ
Unlinked Builds (searchable): Colnago C59 - 5 Years Later; Trek Emonda SL Campagnolo SR; Special Colnago EPQ
Calnago wrote:I’ve never used the Black Prince pads. Just the Swisstop Yellows... worst pads ever but maybe the Yellows now are different than when I had them years ago. But if it was pads I’d expect just kind of more of a uniform braking, be it poor to great and everything in between, but uniform. Pulsing is really something to do with certain spots in the rim that are causing the pads to be more grabby there. A sudden out of trueness certainly does that. A bulge in the brake track could cause it. But those are things you can see. Sounds like your issue can’t be detected visually so I’m inclined to think maybe it’s a resin/carbon mix issue which isn’t quite uniform around the entire brake track. I think I’d just get them to give you a new rim if possible and hope it’s not a problem inherent to those wheels in general. Oh and 0.1mm our of true isn’t enough in my opinion to cause the grabbiness.
thanks for all the insight! it is very helpful.
i am going to let it sit for the evening then give it another go tomorrow. going to take the front brake off and clean it up, reinstall it, just be as meticulous as possible with set up and with pad alignment... i have definitely noticed the eeBrakes are more sensitive to proper set-up than shimano or even sram. that being said, i have now uninstalled and reinstalled my alloy-rimmed front wheel and corresponding brake pads twice today and had no issues on the brief brake test afterwards. i want to narrow the problem down as best as i can before talking to fairwheel monday (or maybe i will get it sorted!).
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You can true the wheel without the truing stand. It's less comfortable and requires some patience but it can be done.
The already mentioned experiment with brakes (testing where the rim touches the pads) is a good direction.
Have the right spoke wrench (and if you use bladed spoke then the spoke holder/key is essential) and some patience and you can do that with great success.
Of course clean things before starting the whole process - especially clean all braking tracks using some alcohol or so. Then put the bike on a stand where you can freely rotate the wheel to be adjusted.
Slowly rotate the wheel and slowly squeeze the brake levers until you hear first noises indicating rim touching the pads, focus on where on the rim that happens and which side it is and adjust the spoke tension (tighten/loose the nipples in small steps - start with something like 1/8 of a turn) around that place to pull the rim the opposite direction a little, repeat again and first check the same part of the rim to see you achieved the desired effect, then focus on other places.. repeat in several steps also with pulling the brake pads closer and closer to the tim until yoy get to the point it the rim consistently either doesn't touch the pads at all, or after pulling the brakes just a tiny bit more it starts to drag almost everywhere. Then you're pretty much done.
To speed things up you don't have to focus on just one place in each iteration but you can easily adjust several places at once - with a little practice. It's still quite slow and requires patience, but it works. If you notice the rim doesn't seem to be nearly perfectly round and thus needs some radial truing as well you can do that as well - and it's easier to do the radial truing first. In this case you can use some stucky tape as a helper for getting better idea where exactly the rim is closer to the hub and where it's the opposite way.
Ideally you should use the spoke tension meter to ensure that you're withing the spec, but in the case of just small adjustments that isn't really needed.
You can also check this guide for example - and adjust it for your improvised conditions.
https://www.parktool.com/blog/repair-he ... rim-truing
Not sure if it's going to help your case, but might be worth trying.
The rim may have some serious imperfections like too much variance width along the braking track area, out of balance (too uneven weight distribution), problem with the hub, slightly bent axle, or the pulsing may be due to the interaction with the fork or who knows what. But you'll need to start somewhere.
It's also a good idea (and that has already been suggested earlier in this thread) to test the wheels on another bike.
The already mentioned experiment with brakes (testing where the rim touches the pads) is a good direction.
Have the right spoke wrench (and if you use bladed spoke then the spoke holder/key is essential) and some patience and you can do that with great success.
Of course clean things before starting the whole process - especially clean all braking tracks using some alcohol or so. Then put the bike on a stand where you can freely rotate the wheel to be adjusted.
Slowly rotate the wheel and slowly squeeze the brake levers until you hear first noises indicating rim touching the pads, focus on where on the rim that happens and which side it is and adjust the spoke tension (tighten/loose the nipples in small steps - start with something like 1/8 of a turn) around that place to pull the rim the opposite direction a little, repeat again and first check the same part of the rim to see you achieved the desired effect, then focus on other places.. repeat in several steps also with pulling the brake pads closer and closer to the tim until yoy get to the point it the rim consistently either doesn't touch the pads at all, or after pulling the brakes just a tiny bit more it starts to drag almost everywhere. Then you're pretty much done.
To speed things up you don't have to focus on just one place in each iteration but you can easily adjust several places at once - with a little practice. It's still quite slow and requires patience, but it works. If you notice the rim doesn't seem to be nearly perfectly round and thus needs some radial truing as well you can do that as well - and it's easier to do the radial truing first. In this case you can use some stucky tape as a helper for getting better idea where exactly the rim is closer to the hub and where it's the opposite way.
Ideally you should use the spoke tension meter to ensure that you're withing the spec, but in the case of just small adjustments that isn't really needed.
You can also check this guide for example - and adjust it for your improvised conditions.
https://www.parktool.com/blog/repair-he ... rim-truing
Not sure if it's going to help your case, but might be worth trying.
The rim may have some serious imperfections like too much variance width along the braking track area, out of balance (too uneven weight distribution), problem with the hub, slightly bent axle, or the pulsing may be due to the interaction with the fork or who knows what. But you'll need to start somewhere.
It's also a good idea (and that has already been suggested earlier in this thread) to test the wheels on another bike.
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