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Electric trekking bikes: is chain and sprocket wear a problem?

I'm looking at trekking e-bikes which appear to be electric MTBs with mudguards and panniers: same gears, same ranges, same motors.
When I was learning on an MTB and later a road bike, there was a golden rule: with front shifters, never let the chain cross. Inner front chain ring to inner four cassette sprockets, outer chain ring to outer four sprockets, to avoid wear on chain and sprocket teeth.
I went to look at e-trekkers and was horrified to see a single front chain ring leading to a 12 speed cassette, the chain kinking at an awful angle. With my weight plus the motor's torque on it, I can imagine wear is going to be significant.
Am I fussing over nothing or will 1 / 12 speed arrangements on an e-bike chew through components at an alarming rate?


  • webboowebboo Posts: 6,041
    Apparently yes this is the case if you over egg it. You can also go through freehubs without much trouble as well.
  • steve_sordysteve_sordy Posts: 2,438
    edited July 2021
    Don't forget that 12-speed was designed to run from a single ring. If you look closely the chain is different to a 6-speed, and even a 10-speed.

    I have run two mountain bikes that had 1x12 and I actually got much better life than I did with previous 9 and 10 speeds on other bikes. It didn't seem to matter whether they were 3x or 2x. Believe it or not, I was getting 6x the life on the 12-speed, but I suspect (don't know for sure) that this was because the components were at the premium end of the scale.

    I now have a electric mountain bike. It is light for an emtb at 20.4kg and I weigh 92kg in my riding kit. I ride mostly in a sandy environment that is very abrasive. My bike is a 1x11, and the transmission carries most of the design features that made the 12-speed stand out. I am still on my second chain and my second cassette at 3054 miles.

    I changed the first chain at 0.4% length extension at 1706 miles because the SLX cassette was looking worn. My second chain is still less than 0.4% and the XT cassette is also looking fine. I used to get three chains (at about 650mile each) per cassette on my previous MTBs, so the cassette is lasting about as long on my emtb. It is the chains that are doing well!

    Many riders that contribute to the EMTB forum I use complain of short chain life and worn out cassettes and ring, but I suspect that it is either poor cleaning, poor maintenance, or poor shifting technique and possibly all three!

    I have always had mechanical sympathy for my transmission and I believe that I am psychologically incapable of shifting under load. Generally, I keep the bike clean, but it does not get cleaned every ride. But the chain at least gets a wipe and a lube before every ride.

    Edit: I still have the same freehub, motor and battery. New wheel and stem bearings, one set of main pivot bearings. That's it!
  • webboowebboo Posts: 6,041
    According to a mate who sells and repairs ebikes, they are better suited to 8/9 speed cassettes and chains as these are generally more robust. When you starting getting into 11/12 speed lighter and thinner chains this is when problems occur.
  • reaperactualreaperactual Posts: 1,183
    edited July 2021
    I got chatting to a guy on a new Cube emtb at my local park. He's 'only been cruising around the park on it for the last three months' he said.

    Took the bike back for a check up and they've quote him £300 for a new NX Eagle drivetrain.

    I gathered with what he was saying it had nothing to do with the fact it was an ebike but rather he only uses the three smallest cogs.

    Got me wondering if it's down to user error not fully exploiting gearing as a novice rider or possibly does an emtb really need such low gearing with power assist paired with a 50t cassette?
  • errecaldiaerrecaldia Posts: 41

    I am still on my second chain and my second cassette at 3054 miles.But the chain at least gets a wipe and a lube before every ride.

    Do you use oil or dry lube? I'd have thought oiling without cleaning spelt death to sprockets but your longevity figures suggest otherwise!

  • steve_sordysteve_sordy Posts: 2,438
    @errecaldia I use Finish Line Wet to lube the chain. Some say it generates a black chain, but I don't find that at all. Maybe if I never cleaned it and just kept adding lube then it would go black. I only wash the bike when it is becoming obviously mucky. I am not a slovenly owner; I take great pride in my bike, but I am not one of those riders that wash the bike and polish it after every single ride.

    When I do wash it, the chain and gears get a spraying with Hope's censored Sh1fter. Yes that is actually what it is called! They only added the "1" instead of an "i" a few years ago. It is a brake friendly degreaser. Once the transmission is soaked, I agitate it with a special brush for cassettes. I do the ring and the cassette and also the mech. The jockey wheels might need a bit of extra attention. While I'm doing this, the chain is being run through the gears. Then I wash it all off with my watering can (I don't use a hose). Once the bike is finished and dry, I run the chain through an old towel quite a few times until it stops coming up wet. I lube the chain, mech and jockey wheels, then run the chain through the gear range a few times to make the mech move through its range . I then leave it. Before I ride, I wipe the chain through the old towel to remove any surface lube.

    I have a Park Tool chain cleaner and I do use it now and again, but not very often - maybe once or twice per year? (Probably only if the chain looks particularly in need of some TLC). <3

    After washing, I used to spray the chain with TF2 Teflon lube in an attempt to drive out any water from under the chain rollers. It was a tricky job as I had to prevent the spray from drifting onto the brakes. So I stopped doing it and I have not noticed any deterioration in chain life as a consequence. The Finish Line Wet lube seems to have no difficulty displacing the water from under the rollers and between the plates and pins.
  • errecaldiaerrecaldia Posts: 41

    I only wash the bike when it is becoming obviously mucky. I am not a slovenly owner; I take great pride in my bike, but I am not one of those riders that wash the bike and polish it after every single ride.

    Thank you, Steve, for the detail. I also do infrequent but thorough cleans on my road bike and get high mileages from the transmission, although I use a chain cleaner each clean. I use an orange-based degreaser, mainly because I don't want anything which stinks worse in the house, rinse with detergent and water then oil copiously, wiping off excess.

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