Planning drivetrain abuse
Nov. 25th, 2009 03:13 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
johnridleyI went through the 10 old chains hanging on the wall in the garage. Sorted them by how worn they were. The absolute worst was about 5/64th of an inch out at 1 foot, which is barely over the 1/16" that general wisdom says is "definitely time to change the chain" but not "you just wrecked your drivetrain" wear levels. I'm pretty sure that's the one I left on for 3500 miles last time. Almost all of the chains show about 3/64" wear @ 1'. It seems to me that general wisdom is not conservative enough; clearly I've wrecked cogs even while changing chains before they were 1/16" worn.
I've decided to just run this drivetrain into the ground. I found a chain that for some reason got changed out but is only about 1/64" out; it's barely worn. The rollers in it are pretty loose but even with the Park tool, which measures roller slop as well, it's not even very near the 0.75% worn indicator. Given that it didn't have a master link (a link was pressed out with a chain tool) and how sloppy the rollers are, I'm betting this is the chain that the bike shipped with. Given that it's noticeably cheaper than the $6 chains I usually buy, it must really be a piece of junk, but I'm sure it'll move power around just fine.
I used the chain tool to take out another link; I'm only running 28T in the back instead of the 34T the bike shipped with. Then I just pressed the chain together rather than using a master link. That means I'll either have to break the chain apart and press it back together again on every cleaning. I've been looking at on-bike chain cleaners, and I think they'd be fine for most situations, but my chain gets so incredibly dirty that sometimes I need to wash it in hot, soapy water 5 or 6 times before it's even ready to go into degreaser for an hour.
I identified the next two least-worn-out chains in the group, and bagged them. I'm going to change the chain every 1000 miles or so to the next-least-worn-out chain. I'll replace the whole drivetrain when it starts misbehaving. I bet I get 5000 or more miles out of this pile of old junk before buying a new cassette.
Nashbar has cheap SRAM 7 speed cassettes for $15. I just need to wait for a free shipping weekend.
Odometer: 19562 miles
I've decided to just run this drivetrain into the ground. I found a chain that for some reason got changed out but is only about 1/64" out; it's barely worn. The rollers in it are pretty loose but even with the Park tool, which measures roller slop as well, it's not even very near the 0.75% worn indicator. Given that it didn't have a master link (a link was pressed out with a chain tool) and how sloppy the rollers are, I'm betting this is the chain that the bike shipped with. Given that it's noticeably cheaper than the $6 chains I usually buy, it must really be a piece of junk, but I'm sure it'll move power around just fine.
I used the chain tool to take out another link; I'm only running 28T in the back instead of the 34T the bike shipped with. Then I just pressed the chain together rather than using a master link. That means I'll either have to break the chain apart and press it back together again on every cleaning. I've been looking at on-bike chain cleaners, and I think they'd be fine for most situations, but my chain gets so incredibly dirty that sometimes I need to wash it in hot, soapy water 5 or 6 times before it's even ready to go into degreaser for an hour.
I identified the next two least-worn-out chains in the group, and bagged them. I'm going to change the chain every 1000 miles or so to the next-least-worn-out chain. I'll replace the whole drivetrain when it starts misbehaving. I bet I get 5000 or more miles out of this pile of old junk before buying a new cassette.
Nashbar has cheap SRAM 7 speed cassettes for $15. I just need to wait for a free shipping weekend.
Odometer: 19562 miles
