Chain Jumping
10-08-20, 07:28 PM
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Chain Jumping
Hello all! I don't know if this is "ghost shifting" because the gears don't actually shift. But when riding in the hardest gear, which is my favorite since I ride on flat roads, it feels like the chain is skipping, or jumping sporadically. It doesn't cause anything other than a moment of panic, but the jolt always passes, and all is good.
This started following a ride on a wet, dirty road, where I'm sure grit and sand made its way up into my chain and other parts. I don't see any sand in the chain, I hosed my bike down after the ride. This happened last year without dirt knowingly playing a role. I've only been riding for a few years, but I get a tune up annually.
I typically ride about 100 miles a week during the summer, and I'm approaching 400 miles since my last tune up. I am dumb when it comes to gear adjustments, I rely on the experts. Is there an easy fix for dummies (I have all the bike tools for making adjustments) to remedy the chain jumping or not fully engaging? I've done web searches and can't really find a similar issue, or maybe it's worded differently than how I describe it.
Any tips or thoughts on my issue would be most welcomed! Thank you all!
This started following a ride on a wet, dirty road, where I'm sure grit and sand made its way up into my chain and other parts. I don't see any sand in the chain, I hosed my bike down after the ride. This happened last year without dirt knowingly playing a role. I've only been riding for a few years, but I get a tune up annually.
I typically ride about 100 miles a week during the summer, and I'm approaching 400 miles since my last tune up. I am dumb when it comes to gear adjustments, I rely on the experts. Is there an easy fix for dummies (I have all the bike tools for making adjustments) to remedy the chain jumping or not fully engaging? I've done web searches and can't really find a similar issue, or maybe it's worded differently than how I describe it.
Any tips or thoughts on my issue would be most welcomed! Thank you all!
10-08-20, 08:34 PM
#2
Who is Austin Dunbar?
Put your bike in the smallest cog on the back and pedal it backwards. Watch the chain as it passes over the cog to see if any links are tight.
10-09-20, 07:32 PM
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You may need a new cassette. This happened to me earlier this year. My bike was riding fine. No problems. But my chain was worn according to my chain gauge, so I replaced the chain, and when I put the new chain on, it was skipping on one of the gears. A new cassette fixed the problem, but it was a relatively expansive fix considering that the bike was riding fine with the old worn chain.
10-09-20, 09:24 PM
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Welcome to Bike Forums!
Are you doing all or most of your riding on the smallest cog in back? Doing so is a sure fire way to wear that cog very fast, stretching the chain in the process. That cog has the fewest teeth and hence the highest load per tooth, plus because it is small, it has less torque on the hub so you have to pedal harder, accentuating the issue. This isn't necessarily "wrong" but you will have to accept that the cog and chain will have to be replaced very frequently.
Note that for many of us, riding in far "lower" gears is faster overall as well as allowing the use of many cogs and far longer life of cogs and chain. Just for fun, you might try timing your pedaling cadence. Many here try to keep up a cadence of around 90 RPM (15 revolutions in 10 seconds). Racers regularly ride 100 RPM, going as high as 120 for maximum power. These lower gears are also far more friendly to knees and unlike cogs, replacements are very expensive.
Cog wear is very hard to see. By the time you can see a change, it is usually toast. Chain wear is easy to measure. The pin to pin distance of a pair of links is 1" Get a good steel roller or tape measure. Measure 12 pairs. (Measure front of pin to front of pin. Far easier than trying to judge centers.) A new chain will measure 12" exactly. At 12 1/16" it is time to replace the chain. At 12 3/32" both chain and cog are tired and a new chain will probably not run successfully over the worn cog.
In my racing days 45 years ago I worked in a bike shop. I frequently saw the bikes brought in with dead chains, worn small cogs and complaints about the drivetrain. At the time, I was doing 120 miles on my days off riding in the inner chainring and middle of the freewheel (now a cassette). On race day, I spent most of my time in the large chainring and the same cogs in back. I didn't use the smallest cog a lot on the flat even in fast races. And that was when the small cog was 13 teeth, We didn't have 12 teeth then and never even dreamed of 11.
Ben
Are you doing all or most of your riding on the smallest cog in back? Doing so is a sure fire way to wear that cog very fast, stretching the chain in the process. That cog has the fewest teeth and hence the highest load per tooth, plus because it is small, it has less torque on the hub so you have to pedal harder, accentuating the issue. This isn't necessarily "wrong" but you will have to accept that the cog and chain will have to be replaced very frequently.
Note that for many of us, riding in far "lower" gears is faster overall as well as allowing the use of many cogs and far longer life of cogs and chain. Just for fun, you might try timing your pedaling cadence. Many here try to keep up a cadence of around 90 RPM (15 revolutions in 10 seconds). Racers regularly ride 100 RPM, going as high as 120 for maximum power. These lower gears are also far more friendly to knees and unlike cogs, replacements are very expensive.
Cog wear is very hard to see. By the time you can see a change, it is usually toast. Chain wear is easy to measure. The pin to pin distance of a pair of links is 1" Get a good steel roller or tape measure. Measure 12 pairs. (Measure front of pin to front of pin. Far easier than trying to judge centers.) A new chain will measure 12" exactly. At 12 1/16" it is time to replace the chain. At 12 3/32" both chain and cog are tired and a new chain will probably not run successfully over the worn cog.
In my racing days 45 years ago I worked in a bike shop. I frequently saw the bikes brought in with dead chains, worn small cogs and complaints about the drivetrain. At the time, I was doing 120 miles on my days off riding in the inner chainring and middle of the freewheel (now a cassette). On race day, I spent most of my time in the large chainring and the same cogs in back. I didn't use the smallest cog a lot on the flat even in fast races. And that was when the small cog was 13 teeth, We didn't have 12 teeth then and never even dreamed of 11.
Ben
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10-09-20, 09:35 PM
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In my racing days 45 years ago I worked in a bike shop. I frequently saw the bikes brought in with dead chains, worn small cogs and complaints about the drivetrain. At the time, I was doing 120 miles on my days off riding in the inner chainring and middle of the freewheel (now a cassette). On race day, I spent most of my time in the large chainring and the same cogs in back. I didn't use the smallest cog a lot on the flat even in fast races. And that was when the small cog was 13 teeth, We didn't have 12 teeth then and never even dreamed of 11.
10-09-20, 10:02 PM
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First, pinpoint if skipping is happening in the rear or up front.
- Look for wear on rear cassette like was mentioned as well as the front chainrings
- Maybe you bent the derialleur hanger somewhere?
- Likely sometihng with the chain. is it worn out? check with a wear tool.
- Look for wear on rear cassette like was mentioned as well as the front chainrings
- Maybe you bent the derialleur hanger somewhere?
- Likely sometihng with the chain. is it worn out? check with a wear tool.
10-09-20, 10:34 PM
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Could be cable stretching. Have you tried adjusting your rear derailleur?
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