crank vs hub power

Electrically assisted bikes, trikes, etc.
Monkey boy
Posts: 2
Joined: 14 Sep 2021, 10:19pm

crank vs hub power

Post by Monkey boy »

Apologies if this has been done to death.

I’m looking into getting an e bike and wondered what the pros and cons of crank power vs hub power were.
Any advice/experience you can share would be greatly appreciated.

Best regards.

Mb
Oldjohnw
Posts: 7687
Joined: 16 Oct 2018, 4:23am
Location: South Warwickshire

Re: crank vs hub power

Post by Oldjohnw »

I have no experience of bb power. I assume that because of the weight distribution bb as some advantages but I also suspect some disadvantages such as increased chain wear.

My experience is of hub drive - at the front. The expectation is that this would cause wheel spin. I have to say that in 4 years and many miles and heavily laden (at the rear) tours I have experienced this once. It is efficient and, I believe, cheaper.

It is also of importance to consider battery location and whether you have cadence or torque drive.

I could not possibly claim which is best.
Last edited by Oldjohnw on 16 Sep 2021, 1:34pm, edited 2 times in total.
John
PH
Posts: 10685
Joined: 21 Jan 2007, 12:31am
Location: Derby
Contact:

Re: crank vs hub power

Post by PH »

My experience is limited to half a dozen test rides, both on shop demos and friends bikes.
I had no hesitation in choosing a torque sensing crank motor. I found it more akin to the experience of cycling, just a multiplying of the effort in a way that feels entirely natural and predictable. I found hub drive motors, front and rear, felt you were being motored along.
Lots of variables and some degree of personal preference, plus as I said my experience is limited, trying before buying is IMO essential.
User avatar
[XAP]Bob
Posts: 18856
Joined: 26 Sep 2008, 4:12pm

Re: crank vs hub power

Post by [XAP]Bob »

Oldjohnw wrote: 15 Sep 2021, 8:25am It is also of importance to consider battery location and whether you have cadence or torque drive.

I could not possibly claim which is best.
I have to say that I think the cadence/torque sensing differences are huge, particularly when starting from a standstill (i.e. when you most benefit from the motor).
Torque is just leagues better.
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.
Oldjohnw
Posts: 7687
Joined: 16 Oct 2018, 4:23am
Location: South Warwickshire

Re: crank vs hub power

Post by Oldjohnw »

[XAP]Bob wrote: 15 Sep 2021, 3:24pm
Oldjohnw wrote: 15 Sep 2021, 8:25am It is also of importance to consider battery location and whether you have cadence or torque drive.

I could not possibly claim which is best.
I have to say that I think the cadence/torque sensing differences are huge, particularly when starting from a standstill (i.e. when you most benefit from the motor).
Torque is just leagues better.
Yes, i have torque and agree. I was meaning I couldn’t say which motor location was best as I have experience of one only
John
swscotland bentrider
Posts: 264
Joined: 3 Aug 2008, 4:38pm

Re: crank vs hub power

Post by swscotland bentrider »

Rather than unpick all that has been said in other posts I'll relate my own experience. I am 72 and have cycled continuously since age 15. I think that background is relevant to what I experienced.
My first foray into electric was with a Giant bottom bracket motored hybrid style bike. Impressively powerful and enormous fun. But heavy. Whenever i rode above the 25kmh cut off point the slightest headwind or gradient slowed me and the motor smoothly took up the drive. I could hear the motor. The bike had some issues and was returned. :(
After fruitlessly looking for a bike in a shop I bought online - a Ribble CGR E. A rear hub motored bike.
I have been absolutely delighted with it. It has a lot less torque than the Giant but feels so much more like a conventional bike. I'm just back from three days in the NE Highlands and the bike was brilliant. My mates are lighter and fitter than me but the bike equalised us nicely. Very happy with my purchase. :D To an experienced / current cyclist there is more than enough power. I can ride into a light headwind at 27/28 kph easily, something that I couldn't do on the Giant.

So, my suggestion is decide what sort of cyclist are you at present. If you need the extra torque go for a bottom bracket motored bike but if you want assistance with hills and headwinds try a hub motored road bike.
Last edited by swscotland bentrider on 16 Sep 2021, 7:07pm, edited 1 time in total.
lowrider
Posts: 140
Joined: 21 Mar 2009, 2:25pm

Re: crank vs hub power

Post by lowrider »

Hub drives are generally cheaper and more reliable and longer lasting than mid drive (though not always).
I have no experience of hub power. I assume that because of the weight distribution hub as some advantages but I also suspect some disadvantages such as increased chain wear.
The opposite is true with a hub drive a mid drive is heavier on the drive chain as that type puts the extra power through the chain while a hub is directly onto the wheel rather than the chain. Mid drive will give a better weight distribution though if that is important to you.

Torque sensing tends to be on mid motors (though not always) Cadence tends to be on Hub drives (though not always).

Received wisdom is that torque sensing has a better feel, closer to a non assisted bike. Cadence is better for weaker cyclists or those with joint issues as with this type you dont need to put in as much effort as you do with torque types (at the expense of range).
KM2
Posts: 735
Joined: 23 Oct 2008, 5:38pm

Re: crank vs hub power

Post by KM2 »

I would have thought that hub motors don’t wear out the drive chain as much as they deweight the chain. Power is already at the business end.
I have a torque sensing hub motor, so they are likely to be available.
Grumpy-Grandad
Posts: 69
Joined: 2 Apr 2021, 11:25am
Location: Crewe, Cheshire

Re: crank vs hub power

Post by Grumpy-Grandad »

I'm riding my first e bike and absolutely love it. It has enabled me to get out onto the roads and enjoy the fresh air.
I only have two speeds .... sedate and stop :wink: ..... due to osteoarthritis I stuggled on a non assisted bike but have no problem now.

I mostly use the 'Eco' setting but will up the assistance on hills if needed.

Both me and my wife ride Carrera Crossfuse bikes :) which have a Bosch motor in the crank .... and very good it is too :D
Steve
Oldjohnw
Posts: 7687
Joined: 16 Oct 2018, 4:23am
Location: South Warwickshire

Re: crank vs hub power

Post by Oldjohnw »

lowrider wrote: 16 Sep 2021, 9:37am Hub drives are generally cheaper and more reliable and longer lasting than mid drive (though not always).
I have no experience of hub power. I assume that because of the weight distribution hub as some advantages but I also suspect some disadvantages such as increased chain wear.
The opposite is true with a hub drive a mid drive is heavier on the drive chain as that type puts the extra power through the chain while a hub is directly onto the wheel rather than the chain. Mid drive will give a better weight distribution though if that is important to you.

Torque sensing tends to be on mid motors (though not always) Cadence tends to be on Hub drives (though not always).

Received wisdom is that torque sensing has a better feel, closer to a non assisted bike. Cadence is better for weaker cyclists or those with joint issues as with this type you dont need to put in as much effort as you do with torque types (at the expense of range).

Sorry - I made a total error in my earlier post which you quote. I have now corrected it.
John
hemo
Posts: 986
Joined: 16 Nov 2017, 5:40pm
Location: West Sussex

Re: crank vs hub power

Post by hemo »

End of the day they all work hub/crank drive whether TS or Cadence type, pointless trying to say one is better then the other.
All I will say is if you prefer to be the bike shop and carry out all your own repairs then a hub bike is the easiest to repair as long as it doesn't have a TS system as the parts are only available from the shop that sells them.
TS branded bikes require a dealer for work, they can't actually do anything except swap out major component parts under warranty once the brand manufacturer agrees to replacing the part. Down side it is slow getting repairs done, after 2 years you are in no mans land as replacements via a dealer are expensive so one needs to factor this in should for instance the motor fails or a battery has an issue. If a battery has an issue you are left with only two options buy a new one or try to remedy any minor issues yourself.
On pedelecs forum some of the guys have the poor unreliable Suntour TS system on Carrera's, the hub is pretty much bullet proof so for the cost of about £80 - £100 they replace all the electronics with KT controllers and PAS system utilising the same hub and battery, just needs a bit of wiring knowhow.
User avatar
simonineaston
Posts: 5101
Joined: 9 May 2007, 1:06pm
Location: ...at a cricket ground

Re: crank vs hub power

Post by simonineaston »

The hub motor option has one trump card, in that it will readily convert an existing cycle into a 'leccy version of the same bike. My nano Brompton feels almost exatly like its non-electric earlier incarnation. In fact the extra weight of the motor / battery up front has damped the "manual" Brompton's tendancy to a slighty skittish front-end.
(rides: Brompton nano & ever-changing Moultons)
stodd
Posts: 447
Joined: 6 Jun 2018, 10:24am

Re: crank vs hub power

Post by stodd »

I agree with the comments about torque sensing above; quick start and 'natural' feel, but greater complexity and transmission wear. One advantage of cadence sensors is that they allow 'ghost' pedalling, keeping the pedals turning but without applying any effort. This can be really important for certain health issues, such as weak knees or diabetes. The max assist of a torque sensor system is typically around 300% of user input, leaving the user with 1/4 of the work to do; not much, but more than some people will be able to produce at the end of a tiring ride. I'm not sure why torque sensor bikes don't have a power setting to allow this, but I'm not aware of any that do.

The immediate power benefit of torque sensors for hill starts has been reduced (but not completely eliminated) by more recent cadence sensors that can kick in power more quickly, even just 1/4 crank revolution.
groberts
Posts: 574
Joined: 27 Apr 2009, 4:15pm
Location: Surrey
Contact:

Re: crank vs hub power

Post by groberts »

stodd wrote: 19 Sep 2021, 9:20am I agree with the comments about torque sensing above; quick start and 'natural' feel, but greater complexity and transmission wear. One advantage of cadence sensors is that they allow 'ghost' pedalling, keeping the pedals turning but without applying any effort. This can be really important for certain health issues, such as weak knees or diabetes. The max assist of a torque sensor system is typically around 300% of user input, leaving the user with 1/4 of the work to do; not much, but more than some people will be able to produce at the end of a tiring ride. I'm not sure why torque sensor bikes don't have a power setting to allow this, but I'm not aware of any that do.

The immediate power benefit of torque sensors for hill starts has been reduced (but not completely eliminated) by more recent cadence sensors that can kick in power more quickly, even just 1/4 crank revolution.
So just to clarify - PAS (cadence) sensors are best for those with knee problems? I have no experience with Torque / bottom bracket drive but following a TKR on my left knee about five years ago converted my Trek 830 with a front hub kit, without which I'd no longer be cycling. I also have a thumb throttle too which helps pulling away i.e. removes the need for high torque force. I'm also now experiencing signifcant degredaton of my right knee which will soon need to be replaced.
swscotland bentrider wrote: 15 Sep 2021, 8:07pm Rather than unpick all that has been said in other posts I'll relate my own experience. I am 72 and have cycled continuously since age 15. I think that background is relevant to what I experienced.
My first foray into electric was with a Giant bottom bracket motored hybrid style bike. Impressively powerful and enormous fun. But heavy. Whenever i rode above the 25kmh cut off point the slightest headwind or gradient slowed me and the motor smoothly took up the drive. I could hear the motor. The bike had some issues and was returned. :(
After fruitlessly looking for a bike in a shop I bought online - a Ribble CGR E. A rear hub motored bike.
I have been absolutely delighted with it. It has a lot less torque than the Giant but feels so much more like a conventional bike. I'm just back from three days in the NE Highlands and the bike was brilliant. My mates are lighter and fitter than me but the bike equalised us nicely. Very happy with my purchase. :D To an experienced / current cyclist there is more than enough power. I can ride into a light headwind at 27/28 kph easily, something that I couldn't do on the Giant.

So, my suggestion is decide what sort of cyclist are you at present. If you need the extra torque go for a bottom bracket motored bike but if you want assistance with hills and headwinds try a hub motored road bike.


Notwithstanding the success of the aforesaid conversion I'm considering an off-the-shelf ebike and had been looking at the Ribble range / maybe the CGR E and would be interested in any further more detailed comments regarding your experience with this bike, in particular: sizing, range, pulling away, changing power assistance, gear ratios, drops v straights, will it take mudgards, can the batteery be removed easily for charging, suitability for touring etc.? One thing I like about my converted bike is that the power control has x5 settings and can be operated without moving your hands off the bars and can therefore easily finesse my needs and requirements, it seems the downtube button could be more awkward by comparison?

Graham
stodd
Posts: 447
Joined: 6 Jun 2018, 10:24am

Re: crank vs hub power

Post by stodd »

groberts wrote: 19 Sep 2021, 7:07pm So just to clarify - PAS (cadence) sensors are best for those with knee problems?
It obviously depends exactly the problem, and also how your ride,but generally I'd say yes.
If you do more than quite short rides your knee might well get tired/strained towards the end. It's then good to keep it moving but without further strain, and that's exactly what you can do with cadence ghost pedalling. (only you know what you would call a short ride and what you would call a strain on the knees)

I notice now that I check the thread in more detail that lowrider had already said something similar
lowrider wrote: 16 Sep 2021, 9:37am Cadence is better for weaker cyclists or those with joint issues as with this type you dont need to put in as much effort as you do with torque types (at the expense of range).
Post Reply