I have ridden a Cytronex bike for over a year, but have started to look at other systems again, mainly just to see what is out there now.
I have just tried a Kalkhoff Agattu Impulse C8 HS (2013 software) at Oxford transport shop and 2 months ago rode the Bosch on a Moustache with NuVinci hub at Velospeed, Berks. Customer service from both places was excellent.
First I will get bare bikes out of the way. Moustache, I found a very harsh ride, too low down position for me, less comfortable, a bit crashy in fact. NuVini hub was interesting, however I still found myself picking a 'fixed gear' and making a discrete shift once I was outside of my cadence range. Seems a CVT is really best paired with an auto-shifter (which they do make, NuVinci Harmony).
Agattu, upright riding position felt nice, very comfortable ride, nice riding position (in my opinion), nice saddle, nice tyres, felt well put together. Standard Nexus on the Agattu is really not for me though...lets the whole bike down...only previously experienced with Nexus-premium/red line-8 and Alfine-8 which change under light load similar to derailleur, whereas Nexus (std) I had to literally stop pedalling for a whole second before it would change! Alfine comes with premium model...not keen on the gold paint job though of premium spec. The black-white two-tone matt paint on the standard Agattu is really nice. Hydraulic rim brakes on this bike were really nice as well, more 'feel' than the Hydraulic discs on the Mouschache...both much better than cable discs for sure.
Anyway, comparing both power systems, for me I felt marginally more 'at home' with the Impulse system, it pulled harder from stationary than the Bosch, felt more direct, less...'wooly'? Hill climbing was great with both systems. Impulse was certainly a bit less noisy than Bosch (but still much more noisy than ye olde Panasonic 26V chain drive).
Regarding pull from standing start, Bosch seemed to want to ramp up the power slowly, even in max power setting (and there are too many settings), whereas Impulse gave flat torque multiplier from stationary which felt much better. I found middle/sport on Impulse was required in traffic for control, whereas I liked max/power for responsiveness on the rest of the ride (max power was too sensitive for slow traffic, but nice to pull away fast the rest of the time). I suspect straight multiplication would deliver the best experience, I believe Bosch system tries to be too 'clever'. Bosch - just let your riders do wheelies and accidentally plough into the car in front if they request it. None of this 'computer says no' stuff.
One comment on the Impulse, there is no minimum cadence requirement, but there seems to be a minimum torque exterted before the motor cuts in. I found myself wishing it responded to smaller torque input, as it tended to cut in and out often when I was at cruising speed. Hopefully this can be improved on. This is easy to live with though, it is not dissimilar to having a cadence sensor on my Cytronex, again something I wish was more sensitive but you get used to it.
Road speed cutoff is implemented in both systems, even on max power I found the Impulse system didn't cut off too harshly, and while I didn't have a speedometer on the Agattu (why not on a £2k bike??), it felt like it pulled to around 16-17 mph quite easily. The Bosch road speed cutoff felt like a much harder limit was being enforced.
As for cadence, my main gripe with the old Panasonic 26V system was the phasing down of torque multiplier at 'normal' cadences (> 60 rpm). It was impossible to climb hills faster than unassisted, because when you brought your legs into 'peak power' cadence, the motor turned off!! Both the Bosch and Impulse systems do not have such a low cadence cutoff, and provide useful assistance at cadences up to 80 rpm. My usual cadence range is 60rpm (absolute min cruising with light torque) to 80 rpm (usual shift-up point), and I found the motor assistance starting to 'flatten off' around my usual up-shift cadence so felt okay - though I would still prefer a bit more rpm. This may be a motor power limit than a 'software cutoff'. More power!!
So the only thing neither system allows you to do is to sprint. If I want to get peak acceleration and hold low gears, I usually spin to 100 rpm, but the motor 'gives up' around 80 rpm. Certainly for hill climbing, you don't need to spin so fast since pulls so strongly, but if you fancy a 'one gear' sprint 0-15mph, you can't do it with these systems. I would liken them to driving a turbo-diesel when you are used to a petrol car, they require completely different gear changing patterns. In my petrol car I like to go 0-60 in 2nd gear, because it's fun, and I guess that is why I like the hub motor on my cytronex...I can sprint to 15 mph in a low gear without the motor cutting out.
Ideally though, since they are sharing the same gearbox, the motor would have a torque curve similar to my legs. Ideally I would like to see such a bike with 3x multiplication up to cadence of 100 rpm. Then it would feel perfect. Perhaps if they made a 'sport' version of the Impulse with torque curve to 100 rpm, with high power motor, kept the standard speed limit, and put it in the standard Agattu (without the gold paint) I would buy it.
So the Impulse is top of my crank drive list, but it's not perfect. I like the power delivery and control, but dislike the lack of cadence rpm and the noise.
Since I like my Cytronex hub motor for flat torque, and high cadence support, but wish I had more torque (as well as control of torque and speed) I hope to try one of these BH E-motion samsung NEO rear hub motor bike at some point, since they have even more power plus a torque sensor on the rear axle. That'd be interesting.
I have just tried a Kalkhoff Agattu Impulse C8 HS (2013 software) at Oxford transport shop and 2 months ago rode the Bosch on a Moustache with NuVinci hub at Velospeed, Berks. Customer service from both places was excellent.
First I will get bare bikes out of the way. Moustache, I found a very harsh ride, too low down position for me, less comfortable, a bit crashy in fact. NuVini hub was interesting, however I still found myself picking a 'fixed gear' and making a discrete shift once I was outside of my cadence range. Seems a CVT is really best paired with an auto-shifter (which they do make, NuVinci Harmony).
Agattu, upright riding position felt nice, very comfortable ride, nice riding position (in my opinion), nice saddle, nice tyres, felt well put together. Standard Nexus on the Agattu is really not for me though...lets the whole bike down...only previously experienced with Nexus-premium/red line-8 and Alfine-8 which change under light load similar to derailleur, whereas Nexus (std) I had to literally stop pedalling for a whole second before it would change! Alfine comes with premium model...not keen on the gold paint job though of premium spec. The black-white two-tone matt paint on the standard Agattu is really nice. Hydraulic rim brakes on this bike were really nice as well, more 'feel' than the Hydraulic discs on the Mouschache...both much better than cable discs for sure.
Anyway, comparing both power systems, for me I felt marginally more 'at home' with the Impulse system, it pulled harder from stationary than the Bosch, felt more direct, less...'wooly'? Hill climbing was great with both systems. Impulse was certainly a bit less noisy than Bosch (but still much more noisy than ye olde Panasonic 26V chain drive).
Regarding pull from standing start, Bosch seemed to want to ramp up the power slowly, even in max power setting (and there are too many settings), whereas Impulse gave flat torque multiplier from stationary which felt much better. I found middle/sport on Impulse was required in traffic for control, whereas I liked max/power for responsiveness on the rest of the ride (max power was too sensitive for slow traffic, but nice to pull away fast the rest of the time). I suspect straight multiplication would deliver the best experience, I believe Bosch system tries to be too 'clever'. Bosch - just let your riders do wheelies and accidentally plough into the car in front if they request it. None of this 'computer says no' stuff.
One comment on the Impulse, there is no minimum cadence requirement, but there seems to be a minimum torque exterted before the motor cuts in. I found myself wishing it responded to smaller torque input, as it tended to cut in and out often when I was at cruising speed. Hopefully this can be improved on. This is easy to live with though, it is not dissimilar to having a cadence sensor on my Cytronex, again something I wish was more sensitive but you get used to it.
Road speed cutoff is implemented in both systems, even on max power I found the Impulse system didn't cut off too harshly, and while I didn't have a speedometer on the Agattu (why not on a £2k bike??), it felt like it pulled to around 16-17 mph quite easily. The Bosch road speed cutoff felt like a much harder limit was being enforced.
As for cadence, my main gripe with the old Panasonic 26V system was the phasing down of torque multiplier at 'normal' cadences (> 60 rpm). It was impossible to climb hills faster than unassisted, because when you brought your legs into 'peak power' cadence, the motor turned off!! Both the Bosch and Impulse systems do not have such a low cadence cutoff, and provide useful assistance at cadences up to 80 rpm. My usual cadence range is 60rpm (absolute min cruising with light torque) to 80 rpm (usual shift-up point), and I found the motor assistance starting to 'flatten off' around my usual up-shift cadence so felt okay - though I would still prefer a bit more rpm. This may be a motor power limit than a 'software cutoff'. More power!!
So the only thing neither system allows you to do is to sprint. If I want to get peak acceleration and hold low gears, I usually spin to 100 rpm, but the motor 'gives up' around 80 rpm. Certainly for hill climbing, you don't need to spin so fast since pulls so strongly, but if you fancy a 'one gear' sprint 0-15mph, you can't do it with these systems. I would liken them to driving a turbo-diesel when you are used to a petrol car, they require completely different gear changing patterns. In my petrol car I like to go 0-60 in 2nd gear, because it's fun, and I guess that is why I like the hub motor on my cytronex...I can sprint to 15 mph in a low gear without the motor cutting out.
Ideally though, since they are sharing the same gearbox, the motor would have a torque curve similar to my legs. Ideally I would like to see such a bike with 3x multiplication up to cadence of 100 rpm. Then it would feel perfect. Perhaps if they made a 'sport' version of the Impulse with torque curve to 100 rpm, with high power motor, kept the standard speed limit, and put it in the standard Agattu (without the gold paint) I would buy it.
So the Impulse is top of my crank drive list, but it's not perfect. I like the power delivery and control, but dislike the lack of cadence rpm and the noise.
Since I like my Cytronex hub motor for flat torque, and high cadence support, but wish I had more torque (as well as control of torque and speed) I hope to try one of these BH E-motion samsung NEO rear hub motor bike at some point, since they have even more power plus a torque sensor on the rear axle. That'd be interesting.
The assist curve is town and touring rather than sport riding for sure.
