Warming up a Kalkhoff

[Hugh]

I'm hoping for a bit of technical advice here.....

Following the link posted by Eddie a couple of days back (below), I was intrigued to see Panasonic 300w motors, plus 14 tooth motor sprockets and larger chainwheels (though these have now gone again). So, if, (hypothetically of course unless for use on private land only ), one were to substitute the above for the existing 11t sprocket and 250w motor on one's Pro Connect S, what would be the effect in terms of potential speed increase, change in assistance level etc?

To continue the hypothesis, if the 10ah battery was also to be replaced by an 18ah one, would the extra capacity make up for the presumed loss in range caused by the extra power and speed?

Just an idea............


(Its a couple of posts back...just put the URL into Goggle translator

Elektrofahrra... p3286.c0.m359 | eBay

If you have a half decent 10ah battery wouldn't a second one makes more sense and be cheaper. Just running around with the one and take second for longer journeys...

remember to look at the raleigh pages as well. 4 -5 pages of bikes and stuff on there...
Last edited by eddieo; Yesterday at 08:20.)

 

[flecc]

If that was just the motor only and not the whole unit, you wouldn't see any increase in assistance, since the power level is set by the controller within the unit. A chainwheel change wouldn't gain any speed either, it would merely change the cadence for a given speed.

The 14 tooth motor sprocket would increase the assisted road speed by 27%, that is from a maximum of about 15 mph to 19 mph. The 18 Ah battery would roughly compensate for the greatly increased consumption.

 

[Hugh]

Thanks Flecc.

It sounds like it's the motor and controller - link here Google Translate

They mention 'latest software' with support factor of 2:1.

Cheers, Hugh

 

[flecc]

Yes, that is the complete unit Hugh, and that makes a big difference. That's not only in the small power wattage increase but in the way it's delivered. Your 2009 unit has an early power phase down starting at around 10 mph with normal gearing, but these later units don't phase down until just before the legal limit.

That means with the 14 tooth sprocket you's have full power to almost 19 mph, but the 18 Ah battery could fall short of matching your current 10 Ah range, depending on how you use the unit. Use it freely with plenty of high power mode and it could get quite greedy.

 

[Teejay]

Yes, I'd noticed that 300W motor unit available on that site and it's got me thinking.

Haven't used it yet, waiting for later in the year and good weather, but lucky me, have got a 2011 PC Disc, which has the 250W motor but with the latest, quite sharp phase-down and X2 assist, subject to the ~400W max output.

Would it worth getting the 300W and swapping it over? It strikes me the power levels are much more sensible at 0.7, 1.3 and 2, you a higher max output and considerably more torque.

Would it be an easy job to do, swapping the units over? It would need the LCD display as well.

Or would it all be a considerable waste of time, effort and money and spoil a perfectly good bike into the bargain? What do those with more knowledge and experience than I think?

 

[flecc]

I'd say a waste of time Teejay, your unit is already so good I think you'd be hard pushed to tell the difference much of the time. Don't forget that in normal power mode you provide near half the motive force and it would still be the same you pedalling with the 300 watt unit, so any gain is in effect halved in normal mode.

However I do agree that the new power steps of 0.7, 1.3 and 2 are probably more sensible, but there will be a penalty in range of course.
.

 

[Hugh]

Wouldn't a larger chainring raise the gearing and thereby increase the speed per given input of motor, or is the motor input governed by roadspeed rather than cadence?

Whatever, a certain hypothetical owner might start saving for a new motor, sprocket and 18ah battery, which, at German prices, isn't such a daunting prospect.

p.s. tried to post yesterday evening but seem to have been having network problems.

Cheers, Hugh

 

[flecc]

No, the chainwheel wouldn't change the gearing relative to the motor speed Hugh, since the motor drives though the 14 tooth sprocket. It would do on the Bosch, Daum and Impulse units since their motors drive the chainwheel. As said, all the Panasonic chainwheel change does is alter the cadence in respect of the motor sprocket speed. With the two choices of chainwheel, the 41 tooth results in a lower cadence than the 35 tooth for a given motor sprocket output speed.

 

[quilly21]

I bumped into a guy with a new Kalkhoff S10 with 18Ah battery, same run as me on a pro connect LX 250w 10Ah battery but with less range, he mostly uses no assist except on the hills and was dissapointed with the range. Very fast though, I'll suggest he reduces the drive sprocket to 11 tooth to improve the range.

 

[flecc]

The S10 is in the faster high speed class so will always have less range. As a guide, the 20 mph high speed 250 watt models lose around 17% of range compared to the legal 15 mph 250 watt models. The even faster high speed models like the S10 lose at least 30% and it can be more loss if the performance is very fully used. 28 mph needs a big increase in power over that needed for 15 mph, with a commensurate leap in consumption which the speed gain doesn't wholly make up for.

The problem is that if a given rider can provide half through pedalling what is needed for 15 mph, they won't provide anything like half what is needed for nearly double that speed. Therefore the motor use and current drain is exponential with speed increase.