looking for advice

[blackspiral]

Hi there, im looking to get back into cycling after a lengthy absence due to crocked knees, I need a strong bike as im a big lad with a big hub motor?.... any advice?....buy your own or make one?

I look forward to the responses!

Blackspiral

 

[JPGiant]

Welcome, I'm reasonably new to the forum and from previous requests of a similar nature I think it would help if you post your height, weight, physical condition and what/where you would like to ride the bike.
Hope this helps.

 

[blackspiral]

Good point mate, yeah

Im 6 foot 4
about 20 stone (hence large)
Fitness level is low, after a rather nasty football injury in my knee.
Some off road riding, muddy trails etc, probably mostly on hard surfaces, oh and I love the look of the fat bikes.... not a skinny bike!

 

[Nealh]

A BPM hub is what you need though you won't find many OEM bikes with one. The Wooh Big Bear but it is a hybrid style, their Fat bike with Bafang G06 hub motor a wider high torque hub motor. Specs suggest it can put out 80nm of torque comparable with output of Bosch/Yamaha mid drives.

 

[Deleted member 22539]

A BPM hub is what you need though you won't find many OEM bikes with one. The Wooh Big Bear but it is a hybrid style, their Fat bike with Bafang G06 hub motor a wider high torque hub motor. Specs suggest it can put out 80nm of torque comparable with output of Bosch/Yamaha mid drives.

If it’s 80nm a crank drive will put down that as you said but you have gears as well helping with the power output
There’s more climbing power with a good crank drive especially off road .

 

[garywfox]

Hi there, im looking to get back into cycling after a lengthy absence due to crocked knees, I need a strong bike as im a big lad with a big hub motor?.... any advice?....buy your own or make one?

I look forward to the responses!

Blackspiral

I was in a similar situation a year or so back. Big lad, crocked knee, returning to cycling. Both of my ebikes have had Bosch crank drives. I tried a couple of hub motor bikes, but they just didn’t ‘feel’ like cycling. My advice would be to try as many as you can before deciding.


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[GLJoe]

I tried a couple of hub motor bikes, but they just didn’t ‘feel’ like cycling. My advice would be to try as many as you can before deciding.

What type of actuation did those use though?
I've found that a hub drive bike that relies on a good torque sensor gives a very natural cycling 'feel'. More so than a Bosch mid drive to be honest.

 

[garywfox]

What type of actuation did those use though?
I've found that a hub drive bike that relies on a good torque sensor gives a very natural cycling 'feel'. More so than a Bosch mid drive to be honest.

Fair point, the feel of any bike will always be subjective. The bikes I tried were both borrowed from work colleagues so weren’t an ideal set up. I wouldn’t rule out a hub drive on a future bike, hence my point in trying before buying.


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[GLJoe]

Fair point, the feel of any bike will always be subjective.

Its not really because its subjective. Its because many bikes (especially cheaper/older) rely on simple cadence sensing to detect whether to apply the power which gives a very unnatural feel to someone who's used to a conventional bike. Because a torque sensor effectively takes your effort and produces additional power proportionately, the response of that type of ebike can be very similar to a normal ride - just with the feeling of super strong legs.

Its a bit like being used to a car that has a conventional throttle, then driving one that has only an on/off switch under your right foot!

 

[garywfox]

That makes sense. The borrowed bikes I tried were both older, and had additional push button “throttles”. The Bosch mid drive which is fitted to both my previous and current bikes would have torque sensors fitted, hence they felt much more natural. I remember that on or off feeling as being the disconcerting part of riding the older bikes.



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[Deleted member 4366]

The on/off feeling comes more from the type of controller rather than the sensor or type of motor. Old controllers had little processing power, but modern ones have very fast and powerful CPUs that allow the engineers the possibility to program much more suitable power profiles.

 

[GLJoe]

The on/off feeling comes more from the type of controller rather than the sensor or type of motor. Old controllers had little processing power, but modern ones have very fast and powerful CPUs that allow the engineers the possibility to program much more suitable power profiles.

More powerful CPUs can certainly allow profiles that do things like apply a soft start type ramp to the power delivery so its not so harsh/ instantaneous in the on/off feeling, but a normal bicycle responds proportionally to your own effort, and the only way I'm aware of that you can give the same type of response/feeling on an ebike is by using a torque sensor.
I realise that many people (especially so it seems on this forum) actually welcome the cadence/throttle type of actuation and are quite negative towards torque based systems, which I understand the reasoning behind for certain situations, however my observations have been that someone who is used to the feel of riding a normal unassisted bike will initially find it a more 'natural' experience jumping on a torque sensor based ebike.

Maybe these modern controllers can deliver proportional control without having a proportional sensor? I'm struggling to work out how they would do this though, so if they do and you know how, I'd be keen to understand how they do it.

 

[Deleted member 4366]

More powerful CPUs can certainly allow profiles that do things like apply a soft start type ramp to the power delivery so its not so harsh/ instantaneous in the on/off feeling, but a normal bicycle responds proportionally to your own effort, and the only way I'm aware of that you can give the same type of response/feeling on an ebike is by using a torque sensor.

If you've ever ridden a bike that has a direct torque multiplication system, you'd know how bad that is. When you're on a hill, the motor surges when you push the pedal down and stalls between the pedal strokes.

All the decent systems that have torque sensors use a combination of torque and cadence in their power algorithms, and there's definitely been a trend in toning down the torque multiplication component in recent years, which is why Bosch had to introduce the MTB mode. The torque sensor is used more to detect that the pedal has been pressed than as a way to regulate the power.

 

[GLJoe]

If you've ever ridden a bike that has a direct torque multiplication system, you'd know how bad that is. When you're on a hill, the motor surges when you push the pedal down and stalls between the pedal strokes.

If you were to ride a bike which only had a crude, direct torque multiplication system with no software smoothing, then yes, you probably would experience what you've described. However while there might indeed be very cheap and nasty models out there that work this way, fortunately I've never had the misfortune of riding these, and thus I've never experienced what you've described. I have however ridden modern bikes based on things like the TMM4 sensors and I've never experienced the 'stalls between pedal strokes' that you mention. Thinking aloud, perhaps if I cycled with an incredibly inappropriate cadence, I might be able to reproduce the effect, but then again ... maybe not.

All the decent systems that have torque sensors use a combination of torque and cadence in their power algorithms, and there's definitely been a trend in toning down the torque multiplication component in recent years, which is why Bosch had to introduce the MTB mode. The torque sensor is used more to detect that the pedal has been pressed than as a way to regulate the power.

I believe you have that backwards. The standard Bosch power modes are made out to be a fairly direct (linear?) multiplier system, but the eMTB mode makes MORE reliance on the torque sensor in that it applies a non linear power response, but the response is varied by and is derived from how hard you press on the pedals. Surely it is therefore toning UP the dependence on torque?
The problem on relying on torque alone, is that the bike can surge forward as soon as you apply weight (even when stationary) to the pedals. To overcome this, Bosch watch for cadence activation as well before applying assist, however this means that your last sentence is also backwards, it should read "the torque sensor is the mechanism that mostly regulates the power, the cadence sensor is used more to detect that the bike has started to move before applying (max) power"