Not a great start with e-bikes. Chain continually jumps off the front sprocket.

[Deleted member 33385]

What I'd do is first of all, buy a new chain, as the one you have has now been subjected to all kinds of grief and it could well be damaged. They are not expensive to replace and they don't last long anyway.

Then rotate your cranks slowly and see if the front chain ring has been bent. Is it straight and true?

Then check that your derailleur hanger isn't bent. Is the chain line straight, relative to the front chain ring?

Then check the tension of the derailleur adjustment, see if that can be tightened.

Then remove links if the derailleur is already at maximum tension.

Through trial and error, that's what I did with mine (plus change cassette and chain, they were worn, into each other and the chain had stretched). Adjustment was a seemingly endless nightmare, but it all works a treat now! The nylon stay is helpful - you know you've got a lot more adjustment to do if it the chain hops past that, or contacts it too often, wearing it away. I was on the verge of buying a Leckie.

I'll have to adjust all over again when I put the 52T chainwheel back on soon (presently 42T). My legs are a lot stronger than they were when I restarted cyling at end of Dec 2020. I hope to in a few weeks or months, be able to tackle some of the local hills without electrical assistance. The wonderful thing about muscles is that they can become stronger, now matter how old we are.

Remove and replace whatever you must. It's worth being through adjusting the drivechain -your wife would be safer (ignore that last part of the sentence if, like me, you're planning on claiming life insurance millions. The trouble is, I think she's doing the same).

 

[Nealh]

For correct chain length remove it from the derailleur and simply place it on the largest toothed gear front and rear, the chain ends should overlap by 2 links for Shimano gearing and 1 link for Sram gearing.

 

[Deleted member 33385]

For correct chain length remove it from the derailleur and simply place it on the largest toothed gear front and rear, the chain ends should overlap by 2 links for Shimano gearing and 1 link for Sram gearing.

nealh, I hope you don't mind my asking, but this looks like a handy way to work out chain length and one which I haven't come across before - could you expand this? Not sure I understand what you mean. Are you saying unlink the chain, take it out of the rear detailleur and... what? Lost me there.

 

[Nealh]

Yes, unlink the chain and remove from derailleur.
Fit chain around largest rear gear (1st gear) and also the largest toothed front chain ring, the two ends should pass each other by two links for Shimano derailleur or one link for SRAM. These are the recommended ways to measure correct chain length, once done simply refit as per normal.

 

[Deleted member 33385]

Yes, unlink the chain and remove from derailleur.
Fit chain around largest rear gear (1st gear) and also the largest toothed front chain ring, the two ends should pass each other by two links for Shimano derailleur or one link for SRAM. These are the recommended ways to measure correct chain length, once done simply refit as per normal.

Thank you nealh! It's great learning a new way to work out chain length - I'll do that when I change my front chainwheel to 52T for speed.

 

[Vim Fuego]

For correct chain length remove it from the derailleur and simply place it on the largest toothed gear front and rear, the chain ends should overlap by 2 links for Shimano gearing and 1 link for Sram gearing.

Finally got round to measuring this today, and it's WAY out, measured at 4-5 links. (Shimano)

How reliable/trusted is this method of measurement? Does it suit all models of bikes and ebikes across this board?

 

[JPGiant]

There are many youtube vids on this subject for you to understand how to measure the chain.

 

[Deleted member 33385]

Finally got round to measuring this today, and it's WAY out, measured at 4-5 links. (Shimano)

How reliable/trusted is this method of measurement? Does it suit all models of bikes and ebikes across this board?

It's a valid method for some bikes:

I tried it the other day, but my bike is too weird, didn't work for me. I removed two links after twiddling screws and trying gears, then twiddled more screws till all the gears worked. Works perfectly now

 

[Vim Fuego]

Appears like too long a chain, got s government voucher, so it's booked in for a service at the local bikeshop, will mention the issue of the chain jumping, and the apparent lack of chain tension and see why conclusion they come to. Hopefully it's as simple as just removing a link.

If so, still going to be feeding this back to retailer/manufacturer.

 

[Deleted member 33385]

Appears like too long a chain, got s government voucher, so it's booked in for a service at the local bikeshop, will mention the issue of the chain jumping, and the apparent lack of chain tension and see why conclusion they come to. Hopefully it's as simple as just removing a link.

If so, still going to be feeding this back to retailer/manufacturer.

There's a chain tensioner you should try first - it's on the back of the derailleur on mine. Or it could be a worn or stretched chain and/or worn rear cassette and/or worn or misaligned chainwheel or bent derailleur, or it could even be outer cables not allowing free movement of the gear cable(s) within. Have a good fiddle first...

 

[Vim Fuego]

So I think have closure on this. The chain was indeed too long, Halfords agreed (the missus didnt buy this from Halfords, just using them for a government free service voucher), they took a link out and played with the B tension screw, and now there is ALOT more tension, everything is working as it should, gear changes are smoother and more responsive, and there is less visible chain bounce whilst riding. It's been in daily use for best part of a month, and no hints of any troubles. Confidence restored!

Never assume just because it's a new bike, it's got a correctly sized chain. Not who was responsible for getting it wrong Haibike or Tredz, but someone did...

 

[Steed]

So I think have closure on this. The chain was indeed too long, Halfords agreed (the missus didnt buy this from Halfords, just using them for a government free service voucher), they took a link out and played with the B tension screw, and now there is ALOT more tension, everything is working as it should, gear changes are smoother and more responsive, and there is less visible chain bounce whilst riding. It's been in daily use for best part of a month, and no hints of any troubles. Confidence restored!

Never assume just because it's a new bike, it's got a correctly sized chain. Not who was responsible for getting it wrong Haibike or Tredz, but someone did...

That's a thumbs up for the much maligned (on this forum) Halfords then!

 

[Vim Fuego]

That's a thumbs up for the much maligned (on this forum) Halfords then!

As with everything, it's likely to very hugely from store to store. The one I used they were really thorough, and would definitely recommend them.

 

[Vim Fuego]

Followup on this thread. so the missus bike has had no chain jumps for 8+ months, until yesterday, when it did it again.

So I decided to get a new chain (as mentioned, the original issues, which were very frequent, could have damaged the chain):

Amazon.co.uk

Here is where it gets interesting.

1/ It's an 8 speed rear hub, so uses the wider format chain (3/32 in meaningless old money measurements, 2.38mm for humans), and this is part of the reason this is so troublesome, as due to the width of the chain, when it jumps off, it's a push the bike home problem, as it wedges between the motor casing and the crank. My SDuro 3.0 is a 10 speed and a narrower chain, and guess what, there is ample room if it slips off (not that is has in 1000 miles of riding) to simply refit. So my first point, this is an issue with the lower spec Sduro 1.0 and the wider chain 8sd setup, and I suspect it was never designed for such a combo.

2/ Bearing in mind a pair of links have already been removed, and mostly solved the issue, it's clear the chain was too long. I have since discovered OEMs fit chains from a huge roll, not the preset lengths you buy in stores, so this perhaps accounts why this one was wrong - someone screwed up. Anyway, looking for replacement chains, they usually come in 114 links for this width. Even with 2 removed, the chain that came off was 116 (so originally 118). I took a punt and ordered a 114, and fitted it, and it runs through all the gears just fine still, so I am thinking based on what's in stores, 114 links is actually the appropriate length for this bike to give it the proper tension (with the cheaper rear shifter). Although I'm no expert on this, so have taken another picture of the rear shifter angle.

Does it appear to now be TOO short?
Will adjusting the "B Screw" move the tensioner back a bit?

 

[sjpt]

You can usually use a narrower chain (eg 10 speed) on an 8 speed. It will probably be more expensive and wear quicker, though.

 

[Vim Fuego]

You can usually use a narrower chain (eg 10 speed) on an 8 speed. It will probably be more expensive and wear quicker, though.

Thanks. This is something I am going to consider if the problem stays as it is (rare, but happens on occasion). It would remove the having to drive out to recover the bike aspect of the problem.

 

[matthewslack]

Thanks. This is something I am going to consider if the problem stays as it is (rare, but happens on occasion). It would remove the having to drive out to recover the bike aspect of the problem.

My cage angles in top and bottom gears. 38T chainwheel, 11/34 cassette.

 

[Nealh]

View attachment 45330

Chain in lowest gear, the derailleur should ideally be at a right angle to the horizontal plain. It is clear in this pic the chain is too short and the mech is being stretched/stressed.

 

[jimriley]

I had the chain jump problem, bought a little gubbins that fits where a front changer would, not happened since. I've also read that the old front changer can be left on and the stops adjusted so it keeps the chain in line.

 

[Vim Fuego]

I had the chain jump problem, bought a little gubbins that fits where a front changer would, not happened since. I've also read that the old front changer can be left on and the stops adjusted so it keeps the chain in line.

Bosxh bikes don't have front changers.