Hi everyone. New to the Pedelec site and impressed by the knowledge and experience evident in the forums. Therefore, I'm going to dive in with a technical question I hope someone can answer.

My wife is about to get a Cube Touring Hybrid Pro (65Nm motor). I have a 2014 Kalkhoff Pro Connect Xion hub drive. We live in a very hilly area and my motor struggles on the steeper ones. According to my handbook, it has a rated torque of 12Nm with 41Nm maximum torque - much less than my wife's. As I am getting older with a progressive lung condition, more help on the hills would be good if I'm to keep up with her. Instead of getting a new bike I wonder if it's possible to re-engineer it with a more powerful motor, possibly a crank-drive one. The rest of the bike is in great condition.

Hi everyone. New to the Pedelec site and impressed by the knowledge and experience evident in the forums. Therefore, I'm going to dive in with a technical question I hope someone can answer.

My wife is about to get a Cube Touring Hybrid Pro (65Nm motor). I have a 2014 Kalkhoff Pro Connect Xion hub drive. We live in a very hilly area and my motor struggles on the steeper ones. According to my handbook, it has a rated torque of 12Nm with 41Nm maximum torque - much less than my wife's. As I am getting older with a progressive lung condition, more help on the hills would be good if I'm to keep up with her. Instead of getting a new bike I wonder if it's possible to re-engineer it with a more powerful motor, possibly a crank-drive one. The rest of the bike is in great condition.

Welcome to the forum.

The Xion motor was / is quite a powerful hub. The torque figures are different for hub and crank motors so I would guess that the 40nm hub is similar to 65nm crank but others will perhaps give a more authoritative answer. How is the battery on your bike? Was the Xion hub direct drive? I cant remember but it didn’t deliver well at slow speeds.

 

Even though the motors might have similar torque/power, a crank drive might well help on steeper hills through the use of gearing, newer geared hubs might also help at slower speeds.

 

It should be possible to fit a new motor. Others will be able to advise further.

Hi welcome to the site

Welcome to the forum.

The Xion motor was / is quite a powerful hub. The torque figures are different for hub and crank motors so I would guess that the 40nm hub is similar to 65nm crank but others will perhaps give a more authoritative answer. How is the battery on your bike? Was the Xion hub direct drive? I cant remember but it didn’t deliver well at slow speeds.

 

Even though the motors might have similar torque/power, a crank drive might well help on steeper hills through the use of gearing, newer geared hubs might also help at slower speeds.

 

It should be possible to fit a new motor. Others will be able to advise further.

Hi Jonah. I wasn't aware there was a difference in torque between hub and crank motors. My battery is fine and I have a spare too which is very handy. Not sure what you mean by 'direct drive' but I haven't noticed a particular problem at slow speeds - except of course climbing really steep hills where I eventually come to a stop as neither the motor nor my legs have what's needed. The motor must overheat on one local very steep stretch of about a mile - it has never made it to the top without a short break. I was wondering whether more modern crank drives had more grunt. As my wife's Cube arrived earlier than expected today, I may take it up there and see.

Hi Jonah. I wasn't aware there was a difference in torque between hub and crank motors. My battery is fine and I have a spare too which is very handy. Not sure what you mean by 'direct drive' but I haven't noticed a particular problem at slow speeds - except of course climbing really steep hills where I eventually come to a stop as neither the motor nor my legs have what's needed. The motor must overheat on one local very steep stretch of about a mile - it has never made it to the top without a short break. I was wondering whether more modern crank drives had more grunt. As my wife's Cube arrived earlier than expected today, I may take it up there and see.

I’ve just checked and the Xion motor is direct drive rather than geared. This means that it has no reduction gears internally. On the plus side this makes it smooth, quiet and reliable. On the downside, the motor will have a slow rpm and tend to create lots of heat when under load at slow speeds (like when going up big hills in lower hears) and be able to deliver reduced effective assist. The motor only operates efficiently between about 8-15mph. If you can keep up a decent speed when climbing, the motor can still provide significant help but once you slip below 8mph it loses its grunt. Geared hub motors have reduction gears internally that mean the motor spins up to 12 x (sometimes more) for each wheel revolution. As the motor spins faster, it is less effected by operating at slower speeds and can still deliver reasonable power even within the range 4-8mph. I really liked the Xion motor when I had one but it needed aggressive hill climbing to make the most of it.

I wasn't aware there was a difference in torque between hub and crank motors

The difference is really how torque is measured. The torque of a hub motor is directly meaningful (for a given wheel size). The effective torque of a crank motor depends on the gears, lower gear, more torque. You could measure the torque at the outside of the chainwheel, but you then need to interpret that to get a useful figure.