Strange friction in front wheel
02-20-12, 01:19 PM
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Strange friction in front wheel
My everyday front wheel is a Tiagra hub laced to a Bontrager rim. I Recently put on a different set of wheels for a while. While the wheel was off, I took undid one side of the bearing house on the hub just to see what was was going on in there (had never looked inside my hubs/bearings before. I followed instructions from Zinn's book for accessing the hub.
Fast forward to a few weeks later and I stick the wheel back into my front fork, give it a spin and...major friction! It spins maybe 1 revolution then sticks into place. I tried clamping the QR at a few different tensions but it didn't fix the problem. Also spun the wheel as I was holding the axle ends in my hand and it spun fine.
I checked to make sure there was no brake rub and my other wheel spins fine. I'm guessing it has something to do with the bearings. Any idea how I could have messed them up?
Fast forward to a few weeks later and I stick the wheel back into my front fork, give it a spin and...major friction! It spins maybe 1 revolution then sticks into place. I tried clamping the QR at a few different tensions but it didn't fix the problem. Also spun the wheel as I was holding the axle ends in my hand and it spun fine.
I checked to make sure there was no brake rub and my other wheel spins fine. I'm guessing it has something to do with the bearings. Any idea how I could have messed them up?
02-20-12, 01:34 PM
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Two things change the bearing adjustment (preload) when wheels are installed.
1- the QR slightly compresses the axle when it's tightened. Most correct adjustments are slightly loose until the QR is tightened.
2- non parallel dropouts can bow the axle (flex it into an arc) which will tighten the bearing. The effects of bowing are greater than the QR compression and I suspect that's the problem. Watch both fork tips as you close the QR and if you see any movement, or change in angle, that's your problem.
Bowing not only tightens the bearing, but can cause a tight fitting seal to drag, either way it has to be attended to and making sure the tips are perfectly parallel.
In your shoes, I'd readjust the cones using stacked washers on both ends so I could adjust with the QR closed. This is also a good diagnostic (before re-adjusting) since if closing the QR on washers off the bike causes the drag you know that's the problem.
1- the QR slightly compresses the axle when it's tightened. Most correct adjustments are slightly loose until the QR is tightened.
2- non parallel dropouts can bow the axle (flex it into an arc) which will tighten the bearing. The effects of bowing are greater than the QR compression and I suspect that's the problem. Watch both fork tips as you close the QR and if you see any movement, or change in angle, that's your problem.
Bowing not only tightens the bearing, but can cause a tight fitting seal to drag, either way it has to be attended to and making sure the tips are perfectly parallel.
In your shoes, I'd readjust the cones using stacked washers on both ends so I could adjust with the QR closed. This is also a good diagnostic (before re-adjusting) since if closing the QR on washers off the bike causes the drag you know that's the problem.
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FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
02-20-12, 01:36 PM
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It spins fine in your hand, and the axle feels smooth by hand ?
Are they cup & cones with loose ball bearings, or sealed bearings in a cartridge ?
If loose balls, and you took apart the axle, then you possibly have the cones too tight. They may feel ok when off the bike, but the qr lever makes them tighter when installing. When adjusting the cones, the axle needs to have a bit of wiggle, that will go away when tightening the qr lever. I have loose dropouts that I use to tighten the qr onto to check.
Edit: FB mentions stacked washers. That serves the same purpose and allows you to feel the axle while under qr pressure.
Are they cup & cones with loose ball bearings, or sealed bearings in a cartridge ?
If loose balls, and you took apart the axle, then you possibly have the cones too tight. They may feel ok when off the bike, but the qr lever makes them tighter when installing. When adjusting the cones, the axle needs to have a bit of wiggle, that will go away when tightening the qr lever. I have loose dropouts that I use to tighten the qr onto to check.
Edit: FB mentions stacked washers. That serves the same purpose and allows you to feel the axle while under qr pressure.
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