climo

I'm considering buying a Bafang, Tongsheng or Sunstar to go on a recumbent trike. Ideally a torque sensing motor so that probably counts the Bafang out. My wife is concerned about noise levels especially given that the mounting position is directly in front of you. I know that the Sunstar is noisy but apparently beds in after about 200 miles and then the noise is about the same as a 2017 Bafang. I've no idea how loud that is - is the 2018 model quieter? I've seen the video comparing the Bafang noise to the Tongsheng. The Tongsheng noise is very noticeable whereas the Bafang is almost silent. Is this other users experience as well? I'm reading, or rather wading through, the massive Tongsheng thread and the failure rate is discouraging but then maybe you only hear when people complain. The quality is variable. We'd be buying 2 motors so quite a sum of money. Our primary usage is long distance touring fully loaded with camping gear. We're planning a 1700km tour in Europe in April and I don't want a nasty surprise of a failure on that trip. So, what do people think of the comparative noise levels and reliability of the Tongsheng unit?

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.

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

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?

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

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.

That's a relief, Whoosh & Kiwi. I was doubting my reasoning (and my sanity). If I keep the max gi below 95 then I'll be ok then it puts the Tongsheng back in the running. On the flat with that load I'm using the top 3 gears on a 50/17 without a motor at about 13-14mph which isn't bad for an old fart. Hills are a struggle & that's what the low gearing and the motor's for.

Apart from the Tongsheng what other drives are there that are both torque sensing and take a double chainring

You're right of course but's relative to wheel size. I would think that Tongsheng figures are for a 26" (or similar) wheel which using 42t front and 11 rear you get 97 gear inches, same gears on my 20" wheel get 81gi. If Tongsheng are happy at 97gi then there's no reason I can't use a 50t which gets me 86gi. Hope that makes sense. But I use a 17t rear sprocket on a rohloff which complicates things a bit so i've referenced the calcs below and done screen shots Here's how: The online derailleur calculator is: http://www.bikecalc.com/gear_inches Put in 26" wheel Front cog 42 rear cog . 11 results are 97gi now go to http://schlumpf.ch/hp/berechnungen/engl_berechnen_nabenschaltung_inch.htm which is a calculator for hub gears circumference 1.59 (20" x 1.75) front 42 rear 17 (which I have fitted) Scroll down to the Rohloff results at the bottom, Column 1:1 (ignore the other columns as they relate to other gear systems) result is 72gi now change the front cog to 50 and results are 86gi, well below the 97gi above Phew! Gave me a headache too! So you see where I'm coming from. imo it can't be stressing the motor. 26" wheel derailleur 42/11 highest gear 20" Rohloff hub gear 42/17 20" Rohloff hub gear 50/17

Are you saying don't use a larger chainring than 42t? Would the spindle size affect the choice of low gears?

Not surprised you're not spinning out as that's 111gi! Smallest chainring on a 110BCD is 34T. With a 17T rear sprocket on the Rohloff that makes 11.16gi lowest. Putting a 50t and the 17t makes 86gi top. Sure, I'll spin out around 20mph but that's high enough with a load for me. I have choice of 13 to 21t sprockets so can tweak those numbers but I'd like to have a super low gear for when the battery runs out.

Ah that explains the plastic. I guess on a long european tour it's best to carry a spare. It'll be going on a 20in trike so does the 42T chainring rule still hold? Compared to a 26in wheel I "lose" 23 gear inches (with a 17T single rear sprocket on the Rohloff) which makes the top gear too low and spinning out at a low speed. Can I put a 50/34 double on it? Would you consider it man enough for the usage above? I'll have a very low gear on the setup, eg most mtb's have a low of 16gi, I'll have 11gi that's about 3 gears lower. Also on a recumbent trike you can't stand up and stomp on the pedals so little in the way of shock loading.

Thanks flecc. afaik they stopped production as most motors were being built into bikes, the retrofit market is small and they couldn't compete with chinese units. Sunstars main business is motorcycle gears so I think that they couldn't be bothered making a niche (for them) product. Are they underpowered compared to the Tongsheng? I know of someone using one on a cargo bike. I understand that originally they were 24v but are now 36v.

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. I need a torque sensor due to a physical issue with synchronising hands & feet. I definitely don't want a throttle and the Rohloff means I can't have a hub motor. The trike weighs 30kg and I tour with a trailer with 30kg in it plus me at 80kg so a heavy load plus it needs to go up steep hills. The only other candidate is the Tongshen TSDZ2 but a few things put me off, plastic gears, a maximum chainring of 42T as larger ones can damage the motor plus build quality is not as good as the metal geared, built in Japan, Sunstar. I guess the question has to be: Is the Sunstar up to the usage and what other alternatives are there?