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Discussion Starter · #1 ·
Anyone know how common it is for the rims to be hitting the brake pads as the wheel flex during sprints and out of the saddle efforts? Anyone know how big of a problem this is? I have no idea whether my rims do it or not, but I'd imagine you'd need some really big clearance to prevent this.
 

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Wheel flex or frame/fork flex. Not completely uncommon during a big sprint. A little unusual for regular out of the saddle climbing.
 

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Discussion Starter · #4 ·
It depends on a lot of factors.

Is the frame cracked? Are the spokes tight enough? Are the hub bearings adjusted correctly? Do you run your brake pads very close to the rim?
I run the pads as far from the rims as possible while maintaining stopping power. I'm 200lbs+ and I'm a sprinter so I assume I get some significant flex. I'm using 50mm carbon wheels. I'd be curious if any tests were ever done to try and quantify power losses from brake pad contact.
 

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Occasionally you see top pro racers flipping the QR on their rear wheel just before a sprint or short, sharp hill.
 

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Yeah. I run about 2mm clearance between pads and rim and bias with more clearance on the NDS where flex is exacerbated by DS chain tension. You can use allen wrenches as a feeler gauges to set/measure clearance if you want to be anal about it.
 

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It depends on a lot of factors.

Is the frame cracked? Are the spokes tight enough? Are the hub bearings adjusted correctly? Do you run your brake pads very close to the rim?
One more: Do you throw the bike dramatically from side to side for that "pro sprinter look?"
 

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I think that is more appropriate for those 15% pitchups!
Not sure if you're serious, but the last I thing I want to do on those 15% grades is "dramatic rocking." Huge waste of energy. Now if you're seriously overgeared (broken rear derailleur cable, for example), you may not have a choice.
 

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Discussion Starter · #11 ·
Yeah. I run about 2mm clearance between pads and rim and bias with more clearance on the NDS where flex is exacerbated by DS chain tension. You can use allen wrenches as a feeler gauges to set/measure clearance if you want to be anal about it.
I probably run 4-5mm of clearance. But I also like to be able to feather the brakes on descents without them touching.
 

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I probably run 4-5mm of clearance.
My levers would bottom with that amount of clearance on both sides. As it is, 2mm on each side provides about 30% free travel at the levers. This will depend on levers and calipers, of course.
 

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Discussion Starter · #13 ·
My levers would bottom with that amount of clearance on both sides. As it is, 2mm on each side provides about 30% free travel at the levers. This will depend on levers and calipers, of course.
Looking at it again, it's more like 3mm on each side
 

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Use Dura-Ace skewers.
Are they functionally different than Ultegra ones? I need skewers to replace my Easton front skewer that's starting to rattle and like internally cammed skewers.
 
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