Bent a chainring on a fixed gear?
01-20-09, 11:08 PM
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Bent a chainring on a fixed gear?
I had a big ride last Sunday. Before hand, I noticed that my chain was not as tight as I'd like, but figured I'd get through it and deal later. But, after the ride (some big declines that required lots of skids) I noticed that my chain was REAL tight. So I went to my LBS today to see what's up with that. I thought the force on my slowing was pulling my rear wheel back on the drop outs that resulted in tightening the chain, but my boy at the shop said I may have bent my chain ring making it slightly oval, and not round anymore. Is that possible? I run brake-less, and only stop via skip/skids. I'm 6'1 190lbs. Just wondering.....now I need a new chain ring cause it's totally noticeable. All good tho, cause I found a sick anodized Pake 46t 170mm for $60 on ebay, but do I need a better/stronger chain ring?
01-21-09, 10:21 AM
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I doubt that your chainring actually is bent... probably shifted a bit.
https://sheldonbrown.com/fixed.html#tension
Try Sheldon's method out before buying a 60 dollar ring.
https://sheldonbrown.com/fixed.html#tension
Try Sheldon's method out before buying a 60 dollar ring.
01-21-09, 11:02 AM
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I had a big ride last Sunday. Before hand, I noticed that my chain was not as tight as I'd like, but figured I'd get through it and deal later. But, after the ride (some big declines that required lots of skids) I noticed that my chain was REAL tight. So I went to my LBS today to see what's up with that. I thought the force on my slowing was pulling my rear wheel back on the drop outs that resulted in tightening the chain, but my boy at the shop said I may have bent my chain ring making it slightly oval, and not round anymore. Is that possible? I run brake-less, and only stop via skip/skids. I'm 6'1 190lbs. Just wondering.....now I need a new chain ring cause it's totally noticeable. All good tho, cause I found a sick anodized Pake 46t 170mm for $60 on ebay, but do I need a better/stronger chain ring?
01-21-09, 04:50 PM
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I doubt that your chainring actually is bent... probably shifted a bit.
shifted? I'm sorry, but what do you mean shifted? Like the bolts weren't tight enough and they moved on the bolts?
shifted? I'm sorry, but what do you mean shifted? Like the bolts weren't tight enough and they moved on the bolts?
01-21-09, 04:58 PM
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Right, but I was actually in the market for a whole new crankset anyways, so we'll see.
01-21-09, 05:09 PM
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when you pedal, does the chain kind of have a "heartbeat" where it bounces at even intervals? If so, you might have a bent chainring.
01-21-09, 05:43 PM
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A heartbeat is almost not enough to explain it. Say I run the cranks real quick to get the wheel going, it slows down fast and when it stops, it almost comes to a hault. It's like if I had a brake pad that wasn't centered on the wall and it would rub on only one part of the wheel. Once it slowed down enough, it would finally come to a hault. Previously, when I would run the cranks the same way, the wheel would run smoothly until finally it came to a slow stop.
01-21-09, 05:45 PM
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A heartbeat is almost not enough to explain it. Say I run the cranks real quick to get the wheel going, it slows down fast and when it stops, it almost comes to a hault. It's like if I had a brake pad that wasn't centered on the wall and it would rub on only one part of the wheel. Once it slowed down enough, it would finally come to a hault. Previously, when I would run the cranks the same way, the wheel would run smoothly until finally it came to a slow stop.
01-21-09, 07:25 PM
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so did the LBS guy see your chainring, and tell you it was bent? It could be the BB as well, slowing you up like that. Is the chain now correctly tensioned, or still super tight? If it's tight, loosen and see if this still occurs.
01-21-09, 07:30 PM
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01-21-09, 08:07 PM
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A heartbeat is almost not enough to explain it. Say I run the cranks real quick to get the wheel going, it slows down fast and when it stops, it almost comes to a hault. It's like if I had a brake pad that wasn't centered on the wall and it would rub on only one part of the wheel. Once it slowed down enough, it would finally come to a hault. Previously, when I would run the cranks the same way, the wheel would run smoothly until finally it came to a slow stop.
01-22-09, 02:18 AM
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Allright, so basically adjust the chain ring bolts to get it centered, which, according to sheldon and ya'll, it should give me some answers. I just think it's weird that they (whomever makes the chain rings and cranks) would make their product with this possibility. Maybe I'm wrong, but if I'm making these products, I would make the bold diameters and the chain ring bolt cavity diameters match, so "shifting" would be impossible. Then again, if I'm running a typical 5 star system, and a certain amount or pressure is put on a given section of the star, then that could actually bend. You know what?, fk it, I'll go get that sick pake crank set I've wanted anyways and go for a ride.
01-22-09, 02:23 AM
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He just offered an opinion and I took it as he's supposed to be the expert. I just ride. Do you really think there could be a BB prob? If that's the case, then I'm really starting to realize the reason some equip costs 200% more than others. Typically, I ride hard with a pretty cheap bike. I"ve been upgrading as I go, but honestly, I've been ignoring the BB.
01-22-09, 02:25 AM
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I doubt that your chainring actually is bent... probably shifted a bit.
https://sheldonbrown.com/fixed.html#tension
Try Sheldon's method out before buying a 60 dollar ring.
https://sheldonbrown.com/fixed.html#tension
Try Sheldon's method out before buying a 60 dollar ring.
01-22-09, 03:37 PM
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He just offered an opinion and I took it as he's supposed to be the expert. I just ride. Do you really think there could be a BB prob? If that's the case, then I'm really starting to realize the reason some equip costs 200% more than others. Typically, I ride hard with a pretty cheap bike. I"ve been upgrading as I go, but honestly, I've been ignoring the BB.
01-22-09, 06:23 PM
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I'd take the bolts off, rotate the chainring one bolt hole, then retighten the bolts back on. Be sure to do the bolt #1, then bolt #3, then #5, then #2, etc. Just get them snug at first, then tighten a bit as you go, to get an even tension on all the bolts. Just like tightening a drum head.
