Bosch Active Plus Gen.3, rotational play between chainring and cranks

[MichaelM]

This is a new bike, It has taken me 3 months to get and I don't want to send it back. It's a Cube Touring Hybrid One.

It hasn't even been ridden with the battery in yet, that is still charging, but the size came out a bit bigger than I expected so I have had a ride round the block to see if I could live with it. It's actually a very comfortable riding position for me, and I was also pleasantly surprised that it feels pretty normal when ridden without any contribution from the motor.

However my wonky heart (hence the e-bike) sank when I detected a little clunk every time the right crank went over centre. Close inspection reveals that the chain ring can be rotated slightly without the cranks moving. The cranks themselves are solid with respect to each other so the chain ring would appear not to be tightly locked to the crankshaft. This is a Gen 3., not one of the earlier small sprocket motors - it's a 38 tooth chainring on the crankshaft. If I hold the chainring steady there's around 3mm of play measured at the end of the cranks. Whether it will feel any different when I have the motor engaged, I don't know so I might have gone off half-cocked, but I can't for the life of me see why there should be any play at all. I'm assuming they are both on the crankshaft, not on concentric shafts?

Had I bought it from a local dealer, which I would have preferred, I would just tote it round there but the only place I could find stock was Bikester. It's taken 6 weeks to deliver what with all the Brexit paperwork, so I'd really like to know what I should expect (e.g are they all like this?) or if it's a simple fix - it shouldn't be worn out, it's visibly brand new.

I'm loath to return it as it looks like being a joy to ride if I can sort it out but obviously I don't want a bike with a serious problem. Helpful comments will be gratefully received.

 

[soundwave]

this is what happens when they dont bother to do a pdi inspection b4 it is delivered.

sounds like the lock ring that holds the sprocket on is a bit loose as should be rock solid.

 

[Gringo]

This is a new bike, It has taken me 3 months to get and I don't want to send it back. It's a Cube Touring Hybrid One.

It hasn't even been ridden with the battery in yet, that is still charging, but the size came out a bit bigger than I expected so I have had a ride round the block to see if I could live with it. It's actually a very comfortable riding position for me, and I was also pleasantly surprised that it feels pretty normal when ridden without any contribution from the motor.

However my wonky heart (hence the e-bike) sank when I detected a little clunk every time the right crank went over centre. Close inspection reveals that the chain ring can be rotated slightly without the cranks moving. The cranks themselves are solid with respect to each other so the chain ring would appear not to be tightly locked to the crankshaft. This is a Gen 3., not one of the earlier small sprocket motors - it's a 38 tooth chainring on the crankshaft. If I hold the chainring steady there's around 3mm of play measured at the end of the cranks. Whether it will feel any different when I have the motor engaged, I don't know so I might have gone off half-cocked, but I can't for the life of me see why there should be any play at all. I'm assuming they are both on the crankshaft, not on concentric shafts?

Had I bought it from a local dealer, which I would have preferred, I would just tote it round there but the only place I could find stock was Bikester. It's taken 6 weeks to deliver what with all the Brexit paperwork, so I'd really like to know what I should expect (e.g are they all like this?) or if it's a simple fix - it shouldn't be worn out, it's visibly brand new.

I'm loath to return it as it looks like being a joy to ride if I can sort it out but obviously I don't want a bike with a serious problem. Helpful comments will be gratefully received.

There’s a little backlash between the crank and chainring on the gen 3 motor. The chainring is not bolted directly to the crank arm like a conventional bike.
if you rotate the pedals back and forth you can feel a little clunk.
its been on every ALP motor I’ve tried (well into double figures).
like you I was worried about it when I first got the bike but 3500 miles later and I’d forgotten all about it until I saw your post It’s not stopped me buying another bike with the ALP motor for my sister.

 

[MichaelM]

Thank you both. The lock ring is certainly not detectably loose, moves with the chain ring, and both appear to move with and be solidly locked to the bit of shiny metal I can see that the lock ring is threaded on to. As the cranks are solid together, I conclude tentatively that the chain ring is indeed on a different, concentric, shaft to to cranks so the backlash must be in the internals of the motor case - a black box as far as I am concerned.

Gringo, the dealer story that "they all do that sir" is in the original How to Avoid Dealing with Complaints procedure but you aren't the dealer and it must be true some times, so thanks for passing on your invaluable experience!

The battery is charged and fitted now, so if it stays dry I'll take a test ride later this morning when I've readjusted the position of the brake levers, shifter etc.. I'd like to think the backlash isn't going to be detectable when the motor and the cranks are both pulling in the same direction.

Thanks again for the responses. What did we do without the internet?

 

[Amoto65]

Nothing wrong with it as stated above, The ALP motor is a great motor I did over 2500 miles on mine around the Peak District and it never missed a beat. Enjoy.

 

[sjpt]

There’s a little backlash between the crank and chainring on the gen 3 motor. The chainring is not bolted directly to the crank arm like a conventional bike.
if you rotate the pedals back and forth you can feel a little clunk.
its been on every ALP motor I’ve tried (well into double figures).
like you I was worried about it when I first got the bike but 3500 miles later and I’d forgotten all about it until I saw your post It’s not stopped me buying another bike with the ALP motor for my sister.

Yes, I feel something similar on my older Active Line motor. It happens if I pedal very lazily as I move between almost zero pressure and just a small amount of pressure. I always assumed it was related to the torque sensor engaging and disengaging. I've never felt it while actually riding 'properly'.

 

[Steed]

Yes, I feel something similar on my older Active Line motor. It happens if I pedal very lazily as I move between almost zero pressure and just a small amount of pressure. I always assumed it was related to the torque sensor engaging and disengaging. I've never felt it while actually riding 'properly'.

I can second that, exactly the same sensation on my 2020 Cube hybrid 1 touring with the latest ALP motor. Not a problem in the slightest. So "they all do that sir" is for once quite correct!

 

[MichaelM]

Thanks for all the comments. They were helpful. A bit of feedback -

I've been for an 8 mile test run in rolling country with a couple of short hills and some headwinds, mainly in ECO, and I am very impressed. Firstly there's no trace whatsoever of the click with the assistance on, as several have found.

I can't compare with anything else having never owned an e-bike before, but I honestly can't feel the assistance as such, it really is like having stronger legs. At one point I was climbing in ECO, in 4th/9, and found that TOUR would let me use 5th and SPORT 6th. At no time did I feel any sense of an invisible hand pushing the bike. Whatever weaknesses the Bosch system might have, there's some seriously good programming gone into it. It's also almost silent.

It has 625 Wh battery, and is now showing a remaining range of 90/50/39/34 for the four assistance levels. This bike is pretty low geared, I must work out the gear table. It won't bother me, just being able to keep in double figures up gradients or in a moderate headwind without struggling is good enough at my current level of fitness.

The Cubes seem to be BIG. I'm comfortable enough on the move, but I'm 5'10" and a 54cm/medium size feels large and I've only got about 2" of saddle post showing. Any bigger and I'd need a mounting block.

 

[soundwave]

 

[Gringo]

I have a Cube Acid One and like the ALP motor, I’m not aware of any faults with this motor, unlike the CX ! I like it so much so that I’ve just picked up a used ladies Crossfuse for my sister.
The thing I don’t like with the Crossfuse is the skinny tires
I’ll be swapping them out for something fatter ASAP my sister like comfort I can’t blame her

 

[MikeS]

I agree with the above comments on the strange backlash you feel with the ALP but you soon get used to it. However since you have taken a squint down there, keep an eye on the 3 (or is it 4) flat head bolts that hold the chainring to whatever it's bolted to. On my Crossfuse two of them backed themselves out - only realised when one got so far out it was catching on something and making a noise. Halfords threadlocked them back in place for me and they have been fine since.
Mike

 

[GLJoe]

The Cubes seem to be BIG. I'm comfortable enough on the move, but I'm 5'10" and a 54cm/medium size feels large and I've only got about 2" of saddle post showing. Any bigger and I'd need a mounting block.

Is your seat height adjusted correctly though?
i.e. as a rough guide, when you're sitting on the saddle (prop yourself up against a wall or something), with the crank all the way down and your HEEL on the pedal (not the ball of your foot as normal), then your leg should be pretty much dead straight, with no bend.

Many people ride with the seat far too low. When they do put the seat to the correct height, it usually feels far too high. Almost as if they need a 'mounting block' to get on the thing ....
;-)

 

[MichaelM]

Is your seat height adjusted correctly though?

Good question. Experience tells me that when I get on a new/strange bike, I tend to be raising the saddle once I get used to it. And indeed I've just checked BB to bum height and it's 700mm on the Cube, and my old Falcon-era Claud Butler hybrid is set at 730mm! And the BB height is similar...so I was actually riding a bit higher on my old bike. I've just checked my riding position on my Brompton, which I have used more recently, and that is 730mm too although the BB is slightly lower on that. That's not low, it's about 5-10mm off full height on the standard Brommie seat post and I'm not a 6 footer.

Measurements prove I'm actually sitting a bit lower on the Cube than on the Claud Butler, and no higher from the ground than I do on the Brommie, so there's obviously an illusion going on...possibly caused by the higher and very wide handlebar of the Cube.

I won't do it yet, but if by mid-summer when I will have done a lot more miles I still feel as if I am riding a highland cow, I might shorten the handlebar a bit - it is 700mm wide, vs. 580mm for the Claud Butler and 500mm for the Brommie (which I have decided to keep, and have ordered a Swytch kit for). I'll keep the height, my dodgy neck needs a sit-up riding position, and there's scope for a slightly shorter stem if I need it.

I digress. I'm actually very pleased that my 'problem' isn't a problem, and that the basic riding position seems OK and is tunable from here. I think this new-fangled electric could get me moving again.

Thanks for all the comments.