Bicycle Mechanics - Fun with tools

I'm sure this is all routine for most of you, but I'm feeling pretty good about my latest bike repairs. I'm trying to reduce my reliance on the local bike shop for repairs and also save some money...

My chain was falling off the front chainring, so I figured I needed a new chain and possibly a new cassette. So I ordered a chain and cassette and used my cheapo bike repair toolset and successfully removed the cassette and cleaned it in Simple Green (now it's all shiny!! :D ). It looked like it was not too worn, so I decided to re-install it with a new chain and see how it worked.

The rear cassette seemed fine, but now the new chain was slipping off the middle chainring. It didn't slip off the small or big chainring, so I figured that I had worn down the middle chainring too much. (My chain was *really* stretched - over an inch longer than it was supposed to be.) I wanted to ride my bike today, so I decided to pay too much at the LBS for an Ultegra middle chainring, the only one they had in stock.

I successfully removed the crank, took apart the chainrings, and put it all back together, and now it doesn't seem to be slipping anymore! (I need to go for a bit of a longer ride to make sure it's all fixed, but it seems good so far.)

Anyway, all that just to say that I'm feeling more confident about performing my own bike repairs. :) Let's just see if my bike doesn't fall apart tomorrow!! (I don't have a torque wrench, so I'm not too sure about the tension on the chainring bolts and cranks...)

Tim

On the subject of chain elongation, I've learned that chains don't "stretch" ... they wear on the bearing surfaces, effectively making the chain longer due to the thinner bearings.

As far as torque is concerned, you should at least get a torque wrench for those fasteners that require a torque value, such as crank bolts, disc rotor bolts, etc. They are expensive, but if you get a nice one (such as a Snap-On 1/4-inch dr), they're guaranteed for life and can be calibrated. You will never need to buy a replacement.

In any case, I suggest going through the Barnett's manuals before you do anything, so you can learn to troubleshoot problems correctly.

Post a pic of your ride! :D

Barnett's manuals were invaluable in helping me take the cranks off. I wouldn't have known how to remove Shimano's spline-fit crank arms without it. Luckily my cheapo tool kit had a tool that's compatible with the Shimano TL-FC15 tool that Barnett's recommends. Those manuals rule!

I went for a longer ride today, and everything is working perfectly now. Must have done it right. :) I'll see about investing in a torque wrench and make sure I got the crank bolt tightened down correctly.

Here's a pic of my bike (before all the work I did, so the cassette's not as shiny in the pic as it is now :D )

Tim

Wow that's a nice bike. I've been thinking about getting an R600 myself. :D

By "slipping off", do you mean that the chain was skipping? Or, do you mean that it was "derailing"?

FWIW, if your chain was elongated by 1" (I'm assuming that this was on the overall length, not over the 1' length usually measured), then most likely, every single cog and ring is toast.

Also, please don't use simple green to clean your chain. If you need to learn more, go here. (http://www.bikeforums.net/showthread.php?s=&threadid=31967)

Originally posted by Dave Stohler
By "slipping off", do you mean that the chain was skipping? Or, do you mean that it was "derailing"?


Skipping. When pedaling hard (e.g. accelerating from a stop or climbing a hill), it would skip over several teeth. Sometimes it would skip so badly that it would derail, but the derailleur's correctly adjusted, so that wasn't the problem.



FWIW, if your chain was elongated by 1" (I'm assuming that this was on the overall length, not over the 1' length usually measured), then most likely, every single cog and ring is toast.


Yeah, about 1" over the whole length. I checked all the cogs pretty well, and they seemed surprisingly unworn. The chainring I replaced was pretty messed up, and the other front rings are a little worn but they're still working just fine. I'll keep 'em clean and try to get as much life as I can from them.



Also, please don't use simple green to clean your chain. If you need to learn more, go here. (http://www.bikeforums.net/showthread.php?s=&threadid=31967)

Cool, thanks for the info. I'll get some citrus degreaser for the future.

Now that I know the consequences of chain wear, I'll be keeping a closer eye on my drivetrain!

Tim

I have always heard that simple green was fine on the cogs and what not, just not for chains. If he is taking the cassette off of the bike, then it os fine to use simple green, just as long as it is rinsed well.

Yeah, about 1" over the whole length. I checked all the cogs pretty well, and they seemed surprisingly unworn. The chainring I replaced was pretty messed up, and the other front rings are a little worn but they're still working just fine. I'll keep 'em clean and try to get as much life as I can from them.

Sorry, but it's really not that easy to tell how cogs are worn from just a glance. When you put the thing together and it still skips, replace your cogs. If you don't, you'll ruin the new chain very quickly, too. A chain that has elongated 1" over the normal approximately 4.75' of a normal chain is then 1/5" elongated over 1'. Most mechanics say that a chain is worn to the point of replacement at 1/16"(about .5% elongation), and worn to the point of causing damage at 1/8" (about 1% elongated). Yours is almost twice this amount. Your chain was 1.6% elongated.

Originally posted by Dave Stohler
When you put the thing together and it still skips, replace your cogs.

Okay. It's not skipping now, so I can assume it's fine, right? Everything seems to be running quite smoothly now.

Tim

Originally posted by Dave Stohler
A chain that has elongated 1" over the normal approximately 4.75' of a normal chain is then 1/5" elongated over 1'. Most mechanics say that a chain is worn to the point of replacement at 1/16"(about .5% elongation), and worn to the point of causing damage at 1/8" (about 1% elongated). Yours is almost twice this amount. Your chain was 1.6% elongated.

I dragged the old chain out to get a more accurate measurement, and it was about 1/8" stretched over 12 links. So it was a little less stretched than my initial 1" estimate, but still pretty bad.

Tim

I would be cautious, what do the teeth on the rear cogs look like? They will become sort of shark tooth shaped. Also if the teeth on the front rings are worn down replace those to. Basicaly what will happen if you use that new chain with worn cogs or rings up front it will ruin the chain and potentioly ruin the new ring up front.. so will cost you quite a bit in the long run.