Can too much trainer time wear cranks quickly?
02-10-11, 06:50 AM
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Can too much trainer time wear cranks quickly?
Ive been on the trainer a lot lately, as i'm sure most of you are.
No matter how smooth i try to be, i do cause the frame to flex a bit in the BB area.
I noticed that the sides my big ring's teeth are showing signs of wear that look a bit advanced for their age.
So i'm wondering, if the trainer is causing the BB to flex more than it normally would (anchored at the rear hub, so the forces have nowhere to go but to the BB), then the cranks are tilting left and right, causing them to rub on the sides of the chain more than usual?
and if this is true, do people buy a set of "trainer cranks" to match their "trainer wheel" to match their "trainer tire"?
No matter how smooth i try to be, i do cause the frame to flex a bit in the BB area.
I noticed that the sides my big ring's teeth are showing signs of wear that look a bit advanced for their age.
So i'm wondering, if the trainer is causing the BB to flex more than it normally would (anchored at the rear hub, so the forces have nowhere to go but to the BB), then the cranks are tilting left and right, causing them to rub on the sides of the chain more than usual?
and if this is true, do people buy a set of "trainer cranks" to match their "trainer wheel" to match their "trainer tire"?
02-10-11, 07:00 AM
#2
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If your BB area is flexing that much you have other issues at hand.......
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02-10-11, 07:08 AM
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Get rollers? Seriously, I notice what seems to be obvious BB flex on a fixed trainer too. I think it is just that when the bike is attached to the trainer, the pivot points are the front tire contact and the rear axle vs the front and rear tire contact points and it seems to amplify the BB flex. While on the road, your wheel is connected to the frame at the axles, the trainer only eliminates the rear wheel effects on frame loading, so, I wouldn't be too concerned that things other than the rear tire are behaving any differently.
02-10-11, 07:20 AM
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I would be really surprised if any modern frame flexed enough to cause any wear issues. My .02 is just ride it and not worry about it. I have never seen anyone who used trainer cranks.
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02-10-11, 08:01 AM
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Maybe it's just staying clean since it's inside and your noticing the rub / shiny spots more since they're not filled with grime?
02-10-11, 08:11 AM
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What appears to be BB flex is an illusion. It's really the trainer flexing. When you look down and see the BB area moving, it's easy to assume that the trainer is rigid, but it's not. Using a trainer is not going to hurt you crank.
Most trainers have cups that fit over the ends of the skewers and apply pressure at that point. Those cups usually have plenty of play in them.
Most trainers have cups that fit over the ends of the skewers and apply pressure at that point. Those cups usually have plenty of play in them.
02-10-11, 08:27 AM
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Cranks don't wear out. Chainrings on a road bike, if kept clean ( and not run with a stretched chain) take a friggin long time to wear out. I've had bikes with easily 25,000 miles on them plus hundreds of hours on a trainer and still running the original chain rings.
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02-10-11, 09:41 AM
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think about the difference in angle between your big ring and the 11, and your big ring and the 21 (or so). That's a lot more than any amount of lateral flex in the BB/crank area.
If you're concerned with component wear, choose a gear that gives a straight chainline, and adjust trainer resistance from there.
If you're concerned with component wear, choose a gear that gives a straight chainline, and adjust trainer resistance from there.
