Sunstar SO3 opinions

[climo]

I may have used top gear (48:11) 3 or 4 times since I got the trike... On the flat and slight downhills I spend most of my time in 48:15 at about 40 km/h. Last season on my flat 27 km training route I got fit enough for about 32 km/h average. That is me and an "empty" trike, just the two small paniers with my gear.

Now I need a motor to get out of the house! First incline is there just in front of me as I type and over 13%, with cold muscles... 15% on the way home Unrestricted the motor will provide 50 km/h cruising speed on the flat

I'm seriously impressed at your speeds. 26" trikes are faster than 20" and your Azub is lighter than my HP Velotechnik but that's still very impressive. Sounds like, with a motor, you should get a 60t

 

[climo]

I know that 48v is more powerful than 36v, though no idea why (I'm no electrician). What effect does that have on the battery range - does it do less miles for a given Ah battery?
How many hours does a battery take to charge?

 

[sjpt]

The energy in a battery is measured in watt hours (wh), which are a multiple of volts (v) and amp house (Ah). So a 48v 10Ah battery is 480wh, and a 36v 10Ah battery just 360wh. Some battery makers (eg Bosch) mark wh as their main published measure.

So if you use the same effective power a 48v battery will give more miles than a 36v one of same aH, pretty much in proportion 48/36 or 4/3, or extra 33%. If you take advantage of the 48v to squeeze maximum power from the motor you will get through the available energy quicker. You will probably still get more miles from the 48v, but not as much as 33% more.

 

[climo]

The energy in a battery is measured in watt hours (wh), which are a multiple of volts (v) and amp house (Ah). So a 48v 10Ah battery is 480wh, and a 36v 10Ah battery just 360wh. Some battery makers (eg Bosch) mark wh as their main published measure.

So if you use the same effective power a 48v battery will give more miles than a 36v one of same aH, pretty much in proportion 48/36 or 4/3, or extra 33%. If you take advantage of the 48v to squeeze maximum power from the motor you will get through the available energy quicker. You will probably still get more miles from the 48v, but not as much as 33% more.

Thanks for the succinct explanation. I'll almost certainly leave the Tongsheng as is and therefore effectively have a larger battery.

 

[anotherkiwi]

You're right and experiment with different chainrings.
Using the motor on low setting how many gears do you increase when using the same rider input. What I mean is, if in a given situation you were in gear 6 are you now in gear 8? Conversely when the motor is off how much resistance are you getting, again in gear usage? Knowing that would help me select a gear to exploit gear 11 in the rohloff which is the most efficient gear. Hope that's clear.
Does a regular front derailleur position work or does the motor push the chainset position out further to the right? ie do I need to mount the FD on an additional bracket so it sits in the correct position above the chainset?

Whoosh, I'd be buying from you - how reliable is the Tongsheng unit? I'm planning a 2000km tour in Europe next year so would take a spare blue gear plus any other spares you recommend. If the motor or other bit failed on tour would you UPS another to me - obviously at my expense.

For the moment my motor is on an upright with 28" wheels.

I would say that on the flat the motor is equivalent to 2 or 3 gears increase - I do ride on the flat without the motor switched on and battery not on the bike from time to time. So on the 8 speed cassette instead of using 3rd gear I would be using 5th on the flat and 6th as soon as there is a gradient. I am much more efficient on the trike so am expecting to have a 3 gear difference. That is up to 25 km/h so the motor will only be used for stop and go traffic and climbing hills. On the upright I am much faster than most cars from 0 to 30 km/h away from the lights and on the flat riding with some effort is about 32 km/h top speed.

You might need to move the derailleur out, with the GSM I will need to move out about 20 mm maybe a bit more. I am going to make an extension piece in CF and use a Sora or equivalent 2 speed derailleur with 16 tooth difference and 48-32 tooth chainwheels. Before I get there I will run the motor with the single 46 tooth standard chainwheel. The drivechain will also be converted to 10 speed and an 11-42 or 11-46 cassette mounted.

 

[anotherkiwi]

I'm seriously impressed at your speeds. 26" trikes are faster than 20" and your Azub is lighter than my HP Velotechnik but that's still very impressive. Sounds like, with a motor, you should get a 60t

We'll save that for the vélomobile...

I can't pull 48:11 any more - too old now, so 60 would not be on the cards. I did look at 50-34 compact double on a 110 BCD spider but I think 48-32 on the 104 BCD spider will suit me just fine.

I got very fit riding a couple of times a week - my Wh usage on the upright went from 7 Wh/km to 5.8 Wh/km over a 4 month period.

 

[jarob10]

Thinking of buying a Sunstar SO3, 250w 36v mid drive motor. They look well built. Leaving the price out of the equation what do people think of them?
I'm aware that they've ceased production & future service may be difficult.
It'll be going on a recumbent trike with a Rohloff IGH which I'll be be keeping.

Be aware, ime the rohloff wont always change gear under load - stopping pedalling to change gear is the only way to ensure a smooth gear change

 

[climo]

Be aware, ime the rohloff wont always change gear under load - stopping pedalling to change gear is the only way to ensure a smooth gear change

I've had rohloffs for 10 years and you're right. However, for me, the advantages outweigh the disadvantages. On a 'bent trike there's not a problem. If you misgear you just stop, select the gear and go, No balancing, no lifting the rear wheel.