42. How to Check For Chain Wear
Demonstrates how to measure a worn out chain using Sheldon Brown’s ruler technique.
One of the most common problems I hear about is chain skip, which is when your pedal slips forward while pedaling under pressure. This is usually either caused by a stiff chain link, worn freehub body, or by a worn chain and freewheel. In this tutorial, we'll learn how to diagnose a worn drivetrain.
Watch the stiff link tutorial first to make sure that isn't your problem. Once you've ruled out a stiff link it's time to check if your chain is actually worn. Chains will 'stretch' over time, because the pins and bushings start to wear, which causes them to start skipping. There are many tools available that measure chain wear (listed to the right of the video), but the easiest and most accurate way to check is by simply using a ruler.
With your chain still on the bike, place the ruler's '0' inch mark directly above the center of one of your chain pins. Now count 12 complete links. A complete link equals 1 inner and 1 outer. A rivet on a new chain should line up exactly with the 12 inch mark using this method.
According to Sheldon Brown, if the rivet is less than 1/16" past the mark, your chain is ok. If it's between 1/16" and 1/8" past the mark you'll likely need a new chain, but your sprockets should be ok. If it's more than 1/8" past the mark, you'll have to replace both the chain and rear sprockets.
The reason you'd have to replace the rear sprockets is because they generally wear with the chain. While the chain is 'stretching', the gap between the teeth on your sprockets also gets wider and wider. This causes the chain to ride up over the teeth and slip while pedaling under pressure. If you install a new chain on an old sprocket, you'll probably be able to see gaps of light through the teeth as shown. Here's how to replace a cassette or a freewheel.
Your front chainrings generally won't need replacing. Because of the larger diameter, the front chainrings usually take twice as long to wear. If worn they are very easy to spot, as they'll start looking like shark teeth. Here's how to replace your chainrings.
Hey, i hope this is the correct subforum
The bike gear cables broke and Im trying to replace them. BUt it's my first time, and I've run into some trouble. I can't seem to get the correct tension in the cable, or there's something wrong with the thing thats supposed to shift gears. I took a video of it. The same tension works for two different positions in the gear shifter thing. How do I fix this?
... Read more >>
I have a problem on my Front bicycle derailleur. I'm new to bike repair so I'm not sure of using the right terms. The chain is on the largest chainring in the front and when I use the small pusher on my shifter, I can hear a click but the chain doesn't move to a smaller chainring. I read online some advices... Read more >>
Hi - my bike won't shift into the big chain ring up front when in the 4 or 5 biggest cogs in the back. In the smaller cogs in back, it shifts ok up front. Any thoughts or suggestions as to what's going on, and how to fix, would be greatly appreciated.
Thanks!... Read more >>
I just finished a complete overhaul if the bike. Everything was cleaned, bearings washed and packed in fresh grease.
When I went to live the chain, I noticed that back pedalling causes the chain to stick:
Any ideas?... Read more >>
Hi, first post, very noobie to bike stuff sorry
(Sorry, it's a little long, tried to keep it concise, sry).
Basically, when the bike is on a stand or even just picking the bike to rear tire is hovering, when pedaling and shifting through the front gears 1,2,3 it shits perfectly. Very smooth and fluid. However, when I'm riding the bike the bike gears will not shift at all!
(Quick necessary back story). Original issue was that the chain was rubbi... Read more >>
My front derailleur is a "Falcon" ---never heard of them! My problem is that I can shift to my large chainring or sprocket but as soon as I let go of the shift lever the derailleur pops the chain right back onto the small ring. W Thanks for your assistance.hen I move the shift lever it "clicks" several times---could there be some type of ratchet that is broken?... Read more >>
I have recently been trying to teach myself more about bike maintenance by doing the work myself (I know horrible idea ). Recently I noticed that my chain was rubbing on my front derailleur so I went and altered the high/low screws on the derailleur. Initially it wasn't moving when I was fiddling with the screws, and in an instructional video they suggested loosening the nut(bolt?) that holds down the shifting cable to allow the derailleur to reset to it's natural positio... Read more >>
So I'm having a very strange problem. I have an old 10 speed Chimo with friction shifters on the stem. A few months back I noticed that when I downshift to the inner chainring, my front derailleur can't shift it back up to the outer chainring. I put it off and only used 5 gears till I tried to fix it today. I flipped the bike upside down and played around with it and it shifted perfectly back and forth. I then righted the bike and had someone hold up the back tire. It also shifted just fine. But when I rode it, once again it refused to shift back up to the outer chainring. Any ideas what this... Read more >>
Hi guys -- I'm new to the forum. Thanks for reading.
I'm fixing up a bike I've had for ~15 years that, sadly, I wasn't able to maintain. The bike is an 18-speed Royce Union mountain bike. Aside from new tubes/tires and a new chain, everything else is original (thumb shifters, both derailleurs are Shimano).
The original chain was just too rusted, so I replaced it, and it runs nicely now. Almost. It's fine on the granny chainring, and it's fine on the big ring, but when it's on the middle ring (the one that I tend to use the most), the chain drags across the inside... Read more >>
Hello I recently got my hands on a 99 trek 6000 and I have been working on it in my free time. When I try to ride it the back chain keeps going down in the gears until it pops off the gear on my wheel help!!... Read more >>
My rear derailleur is horizontal to the bike frame as opposed to vertical.
I can see no obvious reason for this and am unsure of how to fix it.
The bike was shifting just fine until I literally put it down, picked it back up and went to take off and the rear derailleur had the before mentioned issue.
Any help would be much appreciated.... Read more >>
So I picked up a newer Schwinn Jaguar off of craigslist for my son.
This is the first bike I've had around in probably 30 years.
The guy I bought it from pointed out that he had replaced the broken stock 7-speed shifter handle with a 5-speed shifter handle. It rides fine and everything else seems to work. The kid wanted it so we brought it home.
I notice that first gear on the shifter is on the third largest sprocket.
Effectively the bike is set up for gears 3-7 at the moment. If I wanted to gear it down is there a way to set it to go from 2-... Read more >>
I am very new to bicycle mechanics, trying to get an old mountain bike running better. As I was scrubbing off years of gunk from the chain and derailleur, a piece popped off. I have included pics.
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I got a Shimano tourney front derailleur on my bike. Need to replace it. How to get the chain out?. I hope, I do not have to break a link on the chain. I see a rivet in one end of the metal. I do not see screw or bolt tightening the two ends.... Read more >>
I followed the instructions in this video
but I still have the same problem on a Shimano Sora race bike.
With the front derailleur, when I want to switch down from a larger clog to a smaller one, I always have to press the shifter twice: the first time moves the derailleur just a little bit and the second time does the job.
Any hint?... Read more >>