July 7, 20232 yr Yes it does, although to me it doesn't feel like it. The rate of acceleration seems much more pronounced as you move up the PAS levels and it doesn't feel like an "all or nothing" on and off. That might just be my perception though as I've no experience with anything else. What I can say, having used them for a while, is that there is a marked difference between the 350w and the 250w on my other bike. The 250w is slower to accelerate and to maintain a reasonable pace I have to use PAS 3, whereas PAS 2 will suffice with the 350w. On the other hand, the 250w seems a bit better at hill climbing. The 350w bogs down earlier than the 250w and I need to attack the hill at a higher speed. I suspect that the 250w has lower reduction gears, which might explain why the max speed tops out around 16 mph, despite trying it with a different controller and display. They are both good to ride though. (Edit .. The differences could also be down to different RPM as posted by [mention=3847]saneagle[/mention] above. The 250w is an Aikema 95RX and the 350w is a 95RS. Although they are both listed on Aikema's website they don't state RPM or gear ratio). The specifications for those two motors are nearly identical. There aren't separate 250w and 350w versions, neither do they mention different speed versions. Are you running them in different sized wheels, are they both running with the same voltage, and do they have the same max current written on the controller?
July 7, 20232 yr Yes it does, although to me it doesn't feel like it. The rate of acceleration seems much more pronounced as you move up the PAS levels and it doesn't feel like an "all or nothing" on and off. That might just be my perception though as I've no experience with anything else. What I can say, having used them for a while, is that there is a marked difference between the 350w and the 250w on my other bike. The 250w is slower to accelerate and to maintain a reasonable pace I have to use PAS 3, whereas PAS 2 will suffice with the 350w. On the other hand, the 250w seems a bit better at hill climbing. The 350w bogs down earlier than the 250w and I need to attack the hill at a higher speed. I suspect that the 250w has lower reduction gears, which might explain why the max speed tops out around 16 mph, despite trying it with a different controller and display. They are both good to ride though. (Edit .. The differences could also be down to different RPM as posted by [mention=3847]saneagle[/mention] above. The 250w is an Aikema 95RX and the 350w is a 95RS. Although they are both listed on Aikema's website they don't state RPM or gear ratio). MY experience of speed level assists was the Bafang BBS02 mid drive conversion, which, by default, had both speed and power limits on the assist levels. Even at lower levels I found the assist far too powerful until it hit the speed limit which was really sudden. Reprogrammed it to remove the assist level speed limits and lower the power at the lower assist levels which is much better. I can see now (having got one) on a hub motor that the power delivery is quite different.
July 7, 20232 yr The specifications for those two motors are nearly identical. There aren't separate 250w and 350w versions, neither do they mention different speed versions. Are you running them in different sized wheels, are they both running with the same voltage, and do they have the same max current written on the controller? The 250w. kit is on 700c wheels and the 350w. is on 26". They share the same battery. The 250w kit came with a 15amp controller and a Lishui c500 display that doesn't allow speed setting. The 350w kit comes with an 18 amp contoller and c500 display that does allow speed settings. I bought an 18 amp controller from Yose and fitted it to the 250w. This allowed me to derestict the throttle from 6kmh (which is why I did it). As an experiment I tried using the C500 display from the 350w. kit. Despite the display allowing speed settings and the controller being the same as the 350w, the actual max speed would not go above 15.5mph.even when set above that in the display. I came to the conclusion that there is something about the motor that restricts the speed - gears,RPM, I don't know. Judging by some of the other threads it seems that a "how fast will it go" bug infects most who are new to electric bikes and I caught a mild version. In reality I'm not that bothered about speed. At anything above about 16mph "things" can happen a bit too quickly for my liking. I'd much rather go slower, get my head up and look at the scenery. I'm still curious about why the 250w motor won't go faster with the 18 amp contoller and different c500 display though!
July 7, 20232 yr The 250w. kit is on 700c wheels and the 350w. is on 26". They share the same battery. The 250w kit came with a 15amp controller and a Lishui c500 display that doesn't allow speed setting. The 350w kit comes with an 18 amp contoller and c500 display that does allow speed settings. I bought an 18 amp controller from Yose and fitted it to the 250w. This allowed me to derestict the throttle from 6kmh (which is why I did it). As an experiment I tried using the C500 display from the 350w. kit. Despite the display allowing speed settings and the controller being the same as the 350w, the actual max speed would not go above 15.5mph.even when set above that in the display. I came to the conclusion that there is something about the motor that restricts the speed - gears,RPM, I don't know. Judging by some of the other threads it seems that a "how fast will it go" bug infects most who are new to electric bikes and I caught a mild version. In reality I'm not that bothered about speed. At anything above about 16mph "things" can happen a bit too quickly for my liking. I'd much rather go slower, get my head up and look at the scenery. I'm still curious about why the 250w motor won't go faster with the 18 amp contoller and different c500 display though! A motor can't restrict you to 15.5 mph because its speed depends on voltage. If it were 15.5 mph at 36v, it would be 17 mph with a fully-charged battery and 14 mph with a nearly empty one. You'd notice the difference. If it always reaches the same speed, you're limited by the controller. The information you provided is always useful. maybe you don't want to go faster than 15.5 mph, but some others might want to. Also, people can make better judgements aboit suitability of kits for their needs as you can make good judgements about power characteristics and efficiency when you know the max rpm or Kv of a motor. If you had used identical motors on the two bikes, the 700C one would go 7.5% faster, but have 7.5% less torque for accelerating and hill-climbing. The 18A controller would give 20% more torque, which would affect the acceleration and make it easier to sustain a higher speed, plus better hill-climbing. Edited July 7, 20232 yr by saneagle
July 7, 20232 yr The specifications for those two motors are nearly identical. There aren't separate 250w and 350w versions, neither do they mention different speed versions. I've just taken another look at the listing for the Aikema 95RX:- aikema HUB MOTOR Rated Power 250W/350W Speed(km) 27/32 This reads as two versions to me - 250w or 350w with corresponding speeds of 27 and 32 kmh. Knowing the square root of nothing about motors, does this mean that the motors are somehow restricted internally to those speeds? If so it would explain why I can't get more out of the 250w with a more powerful controller.
July 7, 20232 yr I've just taken another look at the listing for the Aikema 95RX:- aikema HUB MOTOR Rated Power 250W/350W Speed(km) 27/32 This reads as two versions to me - 250w or 350w with corresponding speeds of 27 and 32 kmh. Knowing the square root of nothing about motors, does this mean that the motors are somehow restricted internally to those speeds? If so it would explain why I can't get more out of the 250w with a more powerful controller. That's normal. It's because you can run it with 36v or 48v. The higher voltage increases the speed and the power in the same motor.
July 7, 20232 yr That's normal. It's because you can run it with 36v or 48v. The higher voltage increases the speed and the power in the same motor. Ah yes, hadn't thought of that! I guess the mystery will remain.
July 7, 20232 yr Author That's really interesting Can't help thinking the existing assist speed limits do restrict what journeys people will tackle with electric bikes. What average speed did you get with the Carrera ? What is the no load max speed on the Yose hub (if you lift the wheel and apply maximum throttle or max assist level and turn the pedals with the wheel off the ground) ? The average speed I managed on the carrera was 13.4... I'll find ouf the max no load speed next time I'm out on it
July 7, 20232 yr Author The average speed I managed on the carrera was 13.4... I'll find ouf the max no load speed next time I'm out on it Just looking back through my strava... the average speed on the carrera was pretty much identical to my average speed on an 8kg carbon road bike.
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