I waited two weeks for my new chain to arrive, got everything all lined up while on the stand, but when I go to ride it, it skips on the outer sprockets for gears 7-9. Does that mean I need to replace the cassette again? I replaced the chain and sprocket at 5 months. I ride about 55 miles per week with occasional longer rides. That was 18 months ago. Some advice would be great.
Chain issues on Allant 7
- Thread starter Alan Sc
- Start date
fooferdoggie
Well-Known Member
usually its the smaller cogs that wear out. it sounds like it needs a ltitle adjustment. How often do you lube the chain? you should be gettign far more miles then that. I just hit 4200 miles an I wont out the first chain ring but the cassette is fine and I am on my 3rd chain. have you checked your chain wear?
PedalUma
Well-Known Member
- Region
- USA
- City
- Petaluma, CA
Most likely Yes. Chains and cogs wear together. Skipping will become more pronounced if only the chain is replaced. I recommend that you talk to your local Trek dealer about a larger chainring. This will up your gearing so that you can more comfortably ride in the larger gears in the middle of the cassette. The ninth gear has only 11 teeth and all the pressure is distributed on only 5 of them at any given time. But with a 28-t cog 13 or 14 teeth distribute the load at any given time. It is like getting stepped on by a flip flop instead of a stiletto.
Brand new chain. I measured to match the old one. I'm at 4200 miles. This is my second cassette. I have looked at just replacing the outer cogs, but its cheaper to replace the whole unit.
I rarely ride the 9th gear. That gear was skipping within 3 months of getting my bike. I ride eco mode in gears 7 and 8 most of the time. I just didn't think I would need to replace the sprocket again. Maybe I waited too long to replace the chain.
PedalUma
Well-Known Member
- Region
- USA
- City
- Petaluma, CA
Do you have a chain gauge? Look for a CG-3.2. If it fits the small side, replace the chain. If it fits the larger than also replace the cassette. Cleaning and lubricating a chain regularly will make it and the cassette last longer than riding a dirty chain. I wash my new chains to remove all of the shipping gunk. Lots of black comes out of a new chain. I then strip it with solvents, then use dry C3 ceramic lube that does not attract grit. Girt is like sandpaper.
fooferdoggie
Well-Known Member
the smallest cogs i was thinking the largest. yes its wear but its excessive wear. 4200 miles should not be wearing out cogs unless you either let you chain go way too long or you dont shift a lot.
Sparky731
Well-Known Member
- Region
- USA
You are describing cassette sprocket wear. Did you purchase Trek’s ebike chain? It is not standard equipment on the 7. (Should be!) I replaced my 1st chain with the ebike chain & cassette @ 1,200 miles. 2nd cassette at 3,500 miles. 3rd cassette @ 5,600 miles. Now @ 6,700 miles. Chain shows no stretch/wear. Mine is a 7s.
rob feature
Well-Known Member
- Region
- USA
- City
- Greenwood Village, Colorado
~4300 (55 mi/wk x 78 wks) miles on a chain seems excessive. I got just over 1,000 out of my OEM chain before reaching the .5 gap on the static Park Chain Checker. And that's using mostly Eco mode.
fooferdoggie
Well-Known Member
I usually get 2500 but having a worn out cast that fast thats not normal.
I think my last chain was an 9x, I bought a couple of e9 chains for this round. I wonder if my chain is the right length though. Measuring by the last chain I think I'm OK, but I wonder if that would make a difference in the wear of chain and sprocket?
Stefan Mikes
Gravel e-biker
- Region
- Europe
- City
- Mazovia, PL
Do you ride your Allant at higher assistance levels, fast & hard and in top gears often? As others said, the chain wears out, and the worn chain is damaging the small cassette cogs. New chain and worn cassette means chain skipping.
Depending on the price of the cassette, you could replace the entire cassette if it is inexpensive, or just replace the worn cogs in the case of an expensive cluster. It is essential to occasionally measure the chain for wear. When it gets stretched past 0.5%, you need to replace the chain or the cassette cogs will start wearing out. Chain replacement is cheaper than handling the worn cassette later.
1000 miles? With a typical use of an e-bike that is the time to replace the chain. However, in case the e-bike is used hard, the chain might need to be replaced earlier. For instance, I replace the chain on my lightweight e-bike more often than in one year, and it might be every 6 months on my full power e-bike (I ride a lot).
In my experience, it is not worthwhile to invest in expensive "e-bike rated" chains. The cheapest chain matching the number of cassette speeds (9s in your case) and of proper length (number of chain links) would stretch at approximately the same rate as an expensive one. The brand really does not matter. (That's why KMC chains match both Shimano and SRAM drivetrains).
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Sparky731
Well-Known Member
- Region
- USA
Varying the length of the chain seems circumspect. I clean & lube my chain every 300 miles. 5,500 miles on the e-chain — compared to 1,200 miles on the original chain — and it still shows no measurable wear. And I ride hard and fast on my 7s. The 7s‘ Speed motor can produce more torque on the drive chain than the 7‘s Performance motor. I recommend sticking with the manufacture’s specifications for sprocket sizes and chain length.
Stefan Mikes
Gravel e-biker
- Region
- Europe
- City
- Mazovia, PL
I do it before any longer ride, or once a week.
"E-bike specific" Shimano CN-E8000 used for 2,000 miles managed to wear four of my cassette smaller cogs in 10 months.
PedalUma
Well-Known Member
- Region
- USA
- City
- Petaluma, CA
Some derailleurs are better at taking up slack than others. Better long cage MTB ones have a clutch that can allow for an 11-50-t cassette. This is what proper chain length looks like on the largest cog. Chains have rollers. Lube must be present between the roller and its internal guides. That is the only place it matters. It is also the hardest place to reach. I will often immerse a chain in lube after cleaning it. Then suddenly the bike is perky.
Sparky731
Well-Known Member
- Region
- USA
Concur on wear. I replaced the bent stock derailleur with a seemingly more durable Shimano Deore ~1,250 miles and have swapped between SRAM and Shimano cassettes as they wear out. I consider cassettes a relatively low maintenance cost in exchange for the miles I ride.
This picture really helped. Looks like I was running about 5 links too long. Now for the gears. All are smooth except 7 and 8. Any advice there?
PedalUma
Well-Known Member
- Region
- USA
- City
- Petaluma, CA
8 & 7 have the fewest teeth. So they wear out the fastest. Suppose 8 has 11-t. That means all the load is focused on about 5 teeth. For a 28-t cog the load is distributed over about 14 teeth. You may need a new cassette. Is it skipping? Another possibility is a bent derailleur hanger. But that is more remote.
Chain and cassette are both brand new. It is riding up on the cogs in 7 and 8.
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