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 guys, I'm a total novice when it comes to working on bicycles and I read through a lot of posts and I watched some youtube videos but I am really confused on how to get my derailleur back on. I was trying to get my back tire off to change the tube and some how the derailleur inadvertently "fell off". Also, a small metal piece fell off with(I did not see any screws land anywhere), which I have no idea where it goes or what it is for.
I don't know hardly any of the biking terminology so it has made it even more difficult for me to understand what I need to do to get it back... Read more >>
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It's presently 0 Degrees F, with a -16 wind chill in Chicagoland...
It's been ~3 months since the overhaul of the 2 bikes, and I've been alternating them from the repair stand (Bunji Straps hanging from ceiling joist in basement)..
When I started I figured a squirt of oil was all that was needed. I had no idea what nice bikes I had!
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I learned about parts & "Alternate Parts" procurement from LBS, Here, & Internet.
I learned about loose bearings from the first dis-assembly.. and found b... Read more >>
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Which one is a better derailleur or is there a better one?? Any differences between the two other than the model number?? Both have the SGS long cage.
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Thanks... Read more >>
I have a Boarman Hybrid Pro (2010 Model - White http://road.cc/content/review/4160-boardman-urban-pro-ltd) and the I have had a lot of repairs on it recently.
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Hi, I need to replace and old broken RD-TZ30 drlr 7 speed.
Does anyone know if the Shimano Acera M360 7-8 Speed would be an ok replacement?
It is for an old (but much loved) Schwinn Jaguar beach cruiser.
Thanks!... Read more >>
I took off my rear derailleur to clean my bike and i need help putting it back on. Its a shimano derailleur with the hook. And i have a diamondback mountian bike. If anyone can help it would be appreciated!! I dont remember exactly how it was attached to the frame
Jay... Read more >>
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I would like to know why has this happened and at the same time what can be done inorder to fix this problem.. Kindly reply.. ... Read more >>
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I don't exactly know how it happened. I've been trying to fix it for days but nothing works.
So let's say you had a 1-9spd derailleur:
If we would want to shift to the biggest cog we would go to the 1st gear, and if we would want to shift to the smallest cog we would go the the 9th gear. BUT that's not the case in my rear derailleur. I could only go to the 2nd smallest cog, and if I would want to shift to the biggest could I would only have to shift 8 times, this means that I would have 1 more shif... Read more >>
i dont know whats really going on but when i was riding my $300 swiss mountain bike i took a brake then got on and tried to peddle. it spawn around w/o catching the back tire. i checked to see if the chain was on, it was. i was having very slow reaction with the front gears with alot of noise before this. i have not used this bike no more then 4-6 times.
if anyone can help thanks. if i can repair it my self i would rather do that since i dont have cash for a repair person..
(but i did notice it started to catch when i go down the drive way (going somewhat speed... Read more >>
I'm a real novice at this so please make allowances! I was having trouble (front derailleur) shifting up from first to second. When I flicked the shift lever into 2nd, the cage would move across seemingly correctly, but the chain would struggle, make a lot of noise and refuse to shift up. If I pushed the shift lever over a little more - towards 3rd - and held it for a couple of seconds, the chain would move up on to 2nd position and stay there OK. I tried to correct this by increasing the tension a little on the shift wire. The result of that was that it shifts up to 2nd correctly, but wo... Read more >>