Had a nice ride today

[Deleted member 4366]

Saneagle an I went out on our bikes for a ride today. He on his Claude Butler with 48v 500w BPM motor at 36v, and me on my £5 Trax with Xiongda motor.

Everything was going really well. I managed to race a Lycra for about 5 miles until he turned off. At first, we were looking for a new pump, so we went to The Bike Hub in the town park, only to find that it was closed down since January, so we headed off to their other shop in Ironbridge only to find that they had moved. We then did another lap of the River Seven to where they had moved to only to find a different shop that was closed.

We were a bit warm and tired after the racing so stopped to study the map, wherupon we found a route that we hadn't been down before. We planned the new route and then set off again. It was really nice until we came to a gate across the road saying "private". It was a long way back, but then the gate opened and a car came through. The nice young lady told us that we couldn't proceed but there was a track that ran around and joined the road the other side of the estate. Thanking our good fortune and the young lady, we set off down the very very steep track, which slowly deteriorated to the slipperiest muddiest ruttiest track I've ever been down. As we got in deeper and deeper, we reallised that there was no way back. It was so slippery thay Saneagle fell off twice and I once. By the time we reached the road again, we were totally cream crackered, so we decided that a pint was in order. By the time that we got to the pub we were so thirsty and hot that we ordered two pints each. We just settled down to drink them when Saneagle got the call. "Tea's ready. When will you be home?". We therefore had to drink said pints of strong ale and cider rather quickly on an empty stomache. You can guess what's coming next. We were in a hurry, so decided to take a short-cut which involves taking a very narrow zig-zag path up a steep bank. Unfortunately neither of us had the necessary concentration to make the tight turns, so first Saneagle fell off into the hedge laughing his head off, and then I succumbed at the next turn also laughing my head off. Unfortunately, I couldn't extract myself from my hedge with the bike on top of me, so I had to call for help still laughing my head off. If I had been on my own, I'd probably still be there. After that, I was able to pedal home purposefully, unable to feel the normal leg pain and sore bum from a 40 mile ride.

When we got home, I'd used 12.5ah and Saneagle 10.5ah. My motor is set to 20 amps and his 30, so that was a surprise. The Xiongda motor is now totally quiet after the re-greasing..

 

[Arbol]

 

[neptune]

That sounds like a real "Boy`s Own" adventure, you should both be really proud of yourselves. Some times you just have to take the bull by the horns and just give it a go. There may have been only two of you, but I am sure we were all with you in spirit.

 

[Hugh]

but I am sure we were all with you in spirit.

Scotch would do nicely by the sound of things

 

[awol]

I bet the zig-zag shortcut without the pints is probably dead straight.

 

[cwah]

Seaneagle with his bpm and 30A controller used less battery than your xionga??

 

[trex]

both of them rode the same route, same speed, same 36V, either saneagle is 3st lighter or sportier, or the extra grease in the xiongda motor may have turned 2AH into heat over 3 hours of biking. Saneagle: 9.45WH/mile, d8veh: 11.25WH/mile. Not bad really.

 

[Deleted member 4366]

He's the same weight as me.He said he was pedalling quite hard for half the journey. We both used the same amount of amp-hours for the final climb. We've tested a whole load of bikes with different systems side-by-side on our hilly journeys. We normally use the same amount of aHs, or slightly more for me. We used to use 20aH batteries, but are now down to 12aHs, so can't be so lazy.

I conclude that it doesn't make any difference what system you use. At the same speed, with the same pedal effort on the same journey, you use the same amount of battery. All these theoretical efficiency gains are not realised in practice.

The one thing our last journey proves though is that you no longer need high power to climb steep hills. The right 250w motor is more than sufficient. We went up some very steep hills with an all-up weight of 135 kg. The BPM with 30 amps can climb hills much faster.

 

[Arbol]

The one thing our last journey proves though is that you no longer need high power to climb steep hills. The right 250w motor is more than sufficient. We went up some very steep hills with an all-up weight of 135 kg. The BPM with 30 amps can climb hills much faster.

Yes, the only thing missing is people realize of that. Many people, at least in Barcelona, do not even think about an electric bike to substitute their 125cc scooters, even though an e-bike would work equally well, or better (bike specific lanes) than scooters, for urban usage.

But people think about bikes as something that messes you up with grease and suffers lots of wheel punctures, so really not that useful.

These motors d8veh describe, that with 250w can eat hills, plus Schwalbe Marathon Plus, plus Carbon Gates belt and Nuvincis (maybe a crank drive then? or singlespeed?) can be a real world solution for many ... right?

 

[trex]

d8veh did say that saneagle's BPM can climb faster than the xiongda though. The xiongda XD is similar to a crank drive without having to suffer derailleur noise.

 

[cwah]

I conclude that it doesn't make any difference what system you use. At the same speed, with the same pedal effort on the same journey, you use the same amount of battery. All these theoretical efficiency gains are not realised in practice.

So the extra cost of the Xionga may not worth the BPM. The later one is stronger, more reliable and can put more power when necessary

 

[Arbol]

So the extra cost of the Xionga may not worth the BPM. The later one is stronger, more reliable and can put more power when necessary

But it is legal (granted, some BPM are legal).

I do not know which battery d8veh is using, but I believe a 48V 250W version exists. So, if d8veh is using a 36V one, there are still some potential "legal" gains.

d8veh, a question: when you say the Xiongda is able to overcome big hills, do you think this motor could do the same with the singlespeed version? Or is the 5-7spd rear derrailleur essential in order to accomplish that feat?

 

[trex]

So the extra cost of the Xionga may not worth the BPM. The later one is stronger, more reliable and can put more power when necessary

possibly.
The xiongda is a fair bit lighter, a lot stealthier, can easily run on a 9/10AH bottle without fear of killing the bottle.

 

[shemozzle999]

d8veh now 14 "sweet spots" (i.e. maximum motor efficiency) 7 in high speed mode and 7 in low mode speed, using the XD motor. It just needs an exercise to determine, in real life conditions, at what speed in what gear uses the lowest current draw from the battery. This could be done by wiring in a old analogue car ammeter an watching for the bottom current trough while riding on a flat track. The display could then be programmed to run at the ideal speeds. Of course this would have to be done without any rider input.

 

[Deleted member 4366]

We know that with any hub-motor: Highest efficiency is at 2/3 maximum RPM, but you can't always run at that speed due to hills,etc. The Xiongda gives you two chances compared with one from a normal hub-motor. The controller already tries its best to optimise the speed. You can't even doit with a crank-drive, even though you have seven or more chances. You normally want torque rather than efficiency, which means running the motor in an inefficient zone.

If you're lucky enough to have flat rides, you can travel at the most efficient speed, but on my rides, I'm always going either going up or down.