Hi,

 

I had a Focus Aventura 2 from 2018 with the Bosch CX Gen 2 motor. Unfortunately it got stolen and so am looking at a replacement. I want something with the torque ability of the Bosch CX Gen 2 or above.

On looking at options I see the Wisper Wayfarers (M7/M9) had "Super Hi Torque" of 100nm! Yet some were just hybrid bikes and not eMTB. Considering it has more torque than the vast majority of motors on the market, I'm surprised more isn't made of it.

 

I wanted to know if a.) anyone could help me compare Bosch CX Gen 4 and Wisper Super Hi Torque motors b.) Any quantifiable data on the relationship between torque and bike weight e.g. is it easier to climb a 8% gradient with a 85nm motor bike weighing 24kg vs a 60nm motor bike weighing 18kg.

 

Thanks!

 

Andy

If you don't want to put in any effort the heavier bike with the more powerful motor will win. If you want lots of your effort with some help from the motor it's a bit more of a toss up.

It is the all up weight i.e. including you that matters, so that 6kg will be insignificant. Then as long as the motor is operating close to its max efficiency, which means at sufficient pedal rpm, say 70 or more, both will fly up 8%, just in different gears.

 

With identical effort from the rider, supposing the 60Nm motor required my bottom gearing of 38T chain ring to 36T cassette, the 85Nm would manage on (60 / 85) x 36 = 25T. On my 9 speed that is 4th, 24T.

 

That's if it doesn't reach its max power limit first of course!

 

Given the choice, the higher torque makes your life easier in hilly terrain, but I manage on 40Nm which only becomes a hill climbing issue around 12%, and a problem around 15%. 60Nm is likely good for all but serious MTB type hilliness.

lf you liked the Bosch motor, why not buy one of the Cube Ebikes with the Gen 4 Bosch.

 

They start at around £2,000 so a bit dearer than your average hub motor ebike but they are lovely bikes and a step up in quality.

It's important to remember mid-drive delivers its power through the drivetrain which means some efficiency losses through the gears maybe 2-3Nm and mid-drive motors typically peak higher in rpm so their maximum torque can be higher but this may not be sustainable for the motor for as long. Mid-drive delivers its power at the crank where as hub motors deliver it at the hub. These mid-drive motors are meant to be 250W but they push the boundaries of what is acceptable for such motors as Bosch has been shown to be over 700W sometimes almost 800W at peak to deliver their claimed peak torque.

 

Don't get me wrong mid-drive is still the champion of hill climbing but some of the mid-drive motors around 40-60Nm especially configured with higher gearing are at the same hill climbing ability or less than many hub motors. It's really the powerful e-mountain bike mid-drive motors with lower gearing that show superior hill climbing ability. Hub motors also allow for 3x or 2x chainring setups so can easier to have lower mechanical gearing, yes you go slower up the hills but can actually be less effort. So there are many variables.

 

Lastly mid-drive wears out the drivetrain more rapidly so you can often be delivering 2-5x more power through the chain, cassette and chainrings than a standard bike where as hub motor shares the load between the hub motor and the drivetrain massively extending drivetrain life. The point is a mid-drive motor is more likely to be using a more heavily worn drivetrain which reduces efficiency. There are lots of variables though with some people encountering rapid drivetrain wear and others not who are more careful how they use their ebike. If you are someone who likes to go up hills as fast as possible with maximum motor power in the highest gearing and keep changing gear under heavy load with the motor on then your cassette and chain will be toast pretty quickly.

Q128 is rated for max 60nm.

l never thought about the added wear to the drive train (over hub drive) l've gone through three chains, two cassettes and a set of jockey wheels in 3,000 miles.

l never thought about the added wear to the drive train (over hub drive) l've gone through three chains, two cassettes and a set of jockey wheels in 3,000 miles.

Some here might say you are lucky not to have had a broken chain; a single point of failure.

l've never broken a chain, although on my latest ebike l've got the maximum available assistance set at 200% where it can deliver 300%

i have only broken 1 chain and that was because the jockey wheel exploded but use metal ones now.

l've never broken a chain, although on my latest ebike l've got the maximum available assistance set at 200% where it can deliver 300%

Do you have the Cube Ebikes with the Gen 4 Bosch and everything is fine?

l've got the Shimano E8000 system on my ebike, currently on just under 3,300 miles after 13 months

 

But l've never broken a chain on any bike, 13,000 miles on my Mondraker non-electric mountain bike, 3,000 on a Kona Tanuki before that.

 

l don't back off when changing up through the gears on the ebike, which is supposed to be bad for the chain.

 

But as l said, l've got the maximum assistance limited to 2/3 of what it can deliver. l mostly leave it in "Trail" set at 125% and rarely use "Boost" which is set at 200% (maximum available 300%)

 

Maybe that's why the drive train lasts longer.

Edited May 16, 20223 yr by lightning

l've got the Shimano E8000 system on my ebike, currently on just under 3,300 miles after 13 months

 

But l've never broken a chain on any bike, 13,000 miles on my Mondraker non-electric mountain bike, 3,000 on a Kona Tanuki before that.

 

l don't back off when changing up through the gears on the ebike, which is supposed to be bad for the chain.

 

But as l said, l've got the maximum assistance limited to 2/3 of what it can deliver. l mostly leave it in "Trail" set at 125% and rarely use "Boost" which is set at 200% (maximum available 300%)

 

Maybe that's why the drive train lasts longer.

 

What prompts you to change your chain? Do you use a chain stretch measuring tool?

Yes l was getting around 700 miles from a chain before it reached the 0.5 wear limit on the chain checker.

 

However l've started using only GT-85 on my chain, after every ride.

 

Not only does the cassette/jockey wheels etc look pristine (no black gunge) but l am now getting well over 1,000 miles from a chain.

 

Latest chain fitted at 2,400 miles, currently on 3,300 and it's at 0.4 on the chain checker

Hi,

 

I had a Focus Aventura 2 from 2018 with the Bosch CX Gen 2 motor. Unfortunately it got stolen and so am looking at a replacement.

 

What’s your budget?

 

Riese and Müller do very nice bikes with the latest Bosch Performance Line CX motor with 85Nm. They also do belt drive, so no more worn out chains.

 

I have one of their bikes and it is a good bike with a good motor.