Bosch ebike motor reliability

[RobF]

I have to disagree. The logic in my head says that for a road cyclist, pulling away from stationary will put the same load into the pedal as I do. However, the road cyclist is doing that on a 50ish tooth sproket and I'm doing it on 18. Surely this puts more strain on my chain = faster stretching of chain = faster degradation on cassette and sproket.
When I got my bike, I went for the hard nine so that it was good for commuting but also good off-road. The other option was the trekking version....similar price but ultimately I chose the hardnine. Since getting the bike, I have slimmed down the tyres a little but would buying the trekking version meant my components lasted longer? I can't see how it would.
Genuinely interested in others views. It's been a big learning curve over the last 3yrs and I'm still learning!


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My Rose/Bosch Alfine 11 hub gear bike did more than 5,000 miles on the original chain, which might be still going now for all I know because I sold the bike.

A hub gear bike would all but eliminate chain and sprocket wear, and of course, entirely eliminate cassette wear because there isn't one.

As regards accelerating, I don't generally accelerate any faster than a fit road cyclist.

Flecc has a point about the lightweight roadie bike needing less grunt to propel it at the same speed, although I wonder how much difference that makes.

A good quality chain and cassette ought to handle the tiny bit of extra load easily - hub gears do.

 

[RobF]

The maximum torque multiplication from your average crank drive bike is four times what the rider inputs. That's added to what the ride does, so the end result is 500% of what the drive components would normally get. Wear isn't linear with force, it's exponential, so 500% more force could make 1000% more wear.

Yes, if you turn the power right down, so that the motor is giving hardly any assistance, the wear will be much less; however, it can never be as low as an unassisted bike because an electric bike is heavier, so even if you turned the power down to zero, you'd have to pedal harder than an unassisted bike and the forces would therefore be higher.

None of this can compare with a hub-motored bike, where the torque from the motor reduces the forces on the drive train, which is why it tends to last longer than they would on an unassisted bike.

A hub motor must put less strain on the drivetrain.

However, if I'm climbing at the same speed as the roadie, the extra strain can only be that caused by the extra weight of my rig.

I doubt that amounts to much, but can't say for sure.

What I don't get is the posts we have on here - often from non-owners - about crank bikes 'eating' chains.

Usual rider: I refer to legal motors with well designed software which gives smooth power delivery such as the Bosch or Yamaha.

 

[flecc]

Flecc has a point about the lightweight roadie bike needing less grunt to propel it at the same speed, although I wonder how much difference that makes.

Hop on a light one and you'll be astonished at how little effort it takes to accelerate. It's not just the weight, the skinny high pressure tyres make a huge difference.

A good quality chain and cassette ought to handle the tiny bit of extra load easily - hub gears do.

It's not a tiny bit though, the damage is done in acceleration and hill climbing. The averagely fit rider can deliver around 300 watts for ten minutes then. Put him on an e-bike and his 300 watts are matched by up to 500 watts from the motor. That between double and triples the load on the transmission.

On the flat of course there's very little difference, just the minute extra due to the extra drag of a heavier e-bike, so the territory ridden makes a very big difference.
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[RobF]

You might then think hub gears would be regularly going pop but they are not.

The Shimano seven and eight speed hubs appear to be bombproof reliable with a Bosch motor.

My Alfine 11 broke, but then lots of them did, more on push bikes than ebikes due to numbers sold.

 

[GLJoe]

However, if I'm climbing at the same speed as the roadie, the extra strain can only be that caused by the extra weight of my rig.

I doubt that amounts to much, but can't say for sure.

I have a feeling that apart from manufacturing/assembly defects, the biggest factor in how long these things last is mostly down to the user. Both in terms of how well things are maintained and looked after, but also down to how hard they are ridden.
And this doesn't mean that those people getting the high mileages with no issues are automatically wimps! The term 'mechanical sympathy' springs to mind. In all fields of life, Bike, Car, Tin opener... I know some people who seem to give no thought at all to the stresses components go through and just blast away from the outset at full power regardless, while others are super careful, and automatically do things like start easy and build up the power. Even if the final power is quite high, the former always seem to break things at a far faster rate than the latter!

Now of course there is the argument that certain pieces of equipment should effectively 'be up to the job', and often that is a valid point of view, especially with things like mountain bikes, that are (supposedly!) designed to be ridden hard. But nevertheless, pretty much everything WILL break/wear out at some point and the extra forces involved with an ebike just gives the opportunity for that to happen faster if the user is strong and pushes things really hard. Maybe too hard?
The question is - what is 'too hard' ?? and that's a tough one to answer, although IMHO, the majority of eMTBs have parts that are NOT designed robustly enough to be able to withstand long term the types of punishment many riders assume they can take without the bike requiring major component repairs/replacement on a regular basis.

Its probably also got a lot do do with the old maxim:
"Cheap, Light, Strong .... you can only have two ..."
No doubt they could design a bulletproof ebike. But it would weigh 100lbs and most people wouldn't buy it. So as ever, its a juggling act when they design these things.

 

[Andy Elliott]

I have a feeling that apart from manufacturing/assembly defects, the biggest factor in how long these things last is mostly down to the user. Both in terms of how well things are maintained and looked after, but also down to how hard they are ridden.
And this doesn't mean that those people getting the high mileages with no issues are automatically wimps! The term 'mechanical sympathy' springs to mind. In all fields of life, Bike, Car, Tin opener... I know some people who seem to give no thought at all to the stresses components go through and just blast away from the outset at full power regardless, while others are super careful, and automatically do things like start easy and build up the power. Even if the final power is quite high, the former always seem to break things at a far faster rate than the latter!

This is probably true. Although I try to look after mine pretty well, I ride it hard, in all weathers and next to the beach....the knockon effect of this is that parts wear out more quickly.
I'll be interested to see if things are better with my new echain as these claim to be specifically designed for the higher torques. Time will tell.

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[anotherkiwi]

My Wipperman chain on the GSM at >2000 km has seen better days but the chainline on that bike is horrible in the lower gears. As the bike has been parked for a couple of weeks at GFs place the transmission has rusted, I don't have that issue parked inside at my place. I use dry lube and the chain has probably been lubricated 3 or 4 times so far.

I don't blast away from a dead stop at full power, most places I can't, stuff gets in the way - walls, throngs of tourists...

The only IGH which has the range of gears I require is the Rohloff. I would love to have a nexus 8 inter but despite running the numbers numerous times the only way I can make it work for me is with a double chainring (or a 2 speed derailleur) which kind of defeats purpose.

I only ride on the road, sometimes that road is gravel but not often. Often the road is very dirty because I live by the seaside.

I am also astounded by the short lifetimes of drive trains posted on here and my conclusion is "you are doing something wrong" or "something isn't set up right" which is kind of the same thing I guess...

 

[flecc]

The Shimano seven and eight speed hubs appear to be bombproof reliable with a Bosch motor.

Following Shimano's early protests about exceeding the torque limts of their hub gears, Bosch reduced the power of units sold for hub gear e-bikes,

Regardless of that, as you know large number of today's crank unit users are suffering ridiculously short chain and sprocket lives. And the reason for that is as I've explained, the two to three times power transmitted compared to average unpowered cyclists.

If there wasn't any extra power, no-one would buy e-bikes, there'd be no point.
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[Deleted member 4366]

You might then think hub gears would be regularly going pop but they are not.

The Shimano seven and eight speed hubs appear to be bombproof reliable with a Bosch motor.

They can't take the loads. That's why Bosch supply a detuned 40Nm for them and 80Nm for cassette gears, and it's one of the reasons you don't see many hub-geared bikes with crank motors because manufacturers are nervous.

 

[RobF]

Following Shimano's early protests about exceeding the torque limts of their hub gears, Bosch reduced the power of units sold for hub gear e-bikes,

Regardless of that, as you know large number of today's crank unit users are suffering ridiculously short chain and sprocket lives. And the reason for that is as I've explained, the two to three times power transmitted compared to average unpowered cyclists.

If there wasn't any extra power, no-one would buy e-bikes, there'd be no point.
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So ebikers go two or three times faster than a club road rider?

Of course they don't, they go slower if anything.

I would like to know where this 'two or three times power' goes, but I think we will have to agree to disagree.

d8 isn't quite right about the Bosch motor being 'de-tuned' for hub gears.

The highest level of assistance - Turbo - is reduced.

The other levels are slightly lower, but not much.

A hub gear Bosch bike in Sport is pushing out more assistance that a derailer Bosch bike in Tour.

 

[flecc]

So ebikers go two or three times faster than a club road rider?

Speed increase isn't linear. Two to three times power increase means nothing like the same speed increase, and anyway the 15.5 mph limit intrudes. The gain is in climb speed on steeper hills

As you say we'll have to agree to disagree. I'll stick with the widely reported fact of the greatly increased transmission wear with the more powerful crank units, rather than an opinion with almost no support that I can see.
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[Trevormonty]

They can't take the loads. That's why Bosch supply a detuned 40Nm for them and 80Nm for cassette gears, and it's one of the reasons you don't see many hub-geared bikes with crank motors because manufacturers are nervous.

I knew they detuned the performance line 63nm but thought activeline 48nm was left as is. This may explain why my wifes activeline with nexus 8 doesn't have poke of Shimano Steps on old bike.

NB detuning performance line kind defeats purpose of using that motor, may as well used activeline.

If only Shimano would make 8spd that could handle 75-80nm of torque for MTB drives.

 

[Deleted member 4366]

d8 isn't quite right about the Bosch motor being 'de-tuned' for hub gears.

40Nm vs 80Nm. Hello!

 

[Deleted member 4366]

I knew they detuned the performance line 63nm but thought activeline 48nm was left as is. This may explain why my wifes activeline with nexus 8 doesn't have poke of Shimano Steps on old bike.

NB detuning performance line kind defeats purpose of using that motor, may as well used activeline.

If only Shimano would make 8spd that could handle 75-80nm of torque for MTB drives.

Active line is 40Nm max.

Active line gives 295W compared with Performance Line CX at 600w.

 

[RobF]

40Nm vs 80Nm. Hello!

The different models of motor is something else again.

Kalkhoff, bless 'em, make a Bosch Speed predelec which has an Alfine 11 hub.

 

[anotherkiwi]

I noticed the other day that Rohloff has upgraded the max torque accepted by the speed hub from 130 Nm to 150 Nm. Would that have something to do with the report that they have never had a hub failure?

 

[Deleted member 22539]

Sorry to jump in here as I’m very uneducated on hub gears
But do they do any with straight through axles 12x148 for example

 

[Trevormonty]

Active line is 40Nm max.

Active line gives 295W compared with Performance Line CX at 600w.

Gen2 activeline is 48nm, new Gen3 is 40nm.

Found the motor specs, Performance line 63nm is detuned to 50nm. The activeline plus with hub is still 50nm but turbo assist level eg 270% reduced slightly.

 

[Danidl]

Active line is 40Nm max.

Active line gives 295W compared with Performance Line CX at 600w.

D8veh, I am sure that you are aware that just quoting a torque figure in isolation , without including the rotational speed is insufficient.... A 40 Nm device rotating at 80 rpm , transmits exactly the same power as a 80 Nm device at 40 rpm.

 

[Deleted member 4366]

Gen2 activeline is 48nm, new Gen3 is 40nm.

I think that's Active Line Plus. Basic Active Line is still 40Nm according to Bosch.