Commuter bike build advice

[Bonzo Banana]

Maybe to you, but not to the rest of us.

I was looking at a ebay page that had both models listed with a big banner for direct drive but I can see looking again at pages where only the smaller hub is sold it does say geared. Low weight limits, extremely low torque and the hassle of repairing/replacing gearing I really can't see it as a good option for me.

I see generic gears are available from various sites that mention Bafang but no gearing is sold via violamart's site or from the seller on ebay. Is it the same as Bafang or are replacement gears difficult to get. Maybe it has higher quality metal gearing that is unlikely to need replacement but that seems a stretch. I see there are some upgrade gears for Bafang motors that are metal but they seem to be for their mid-mount motors which are much higher torque.

I've watched a few videos of the Bafang factory on youtube and most of the parts for hub motors seem to be bought in from other suppliers with only assembly and testing done at the Bafang facility which was extensive. Definitely seems like a company that takes quality seriously but maybe the hub designs are using fairly generic parts. In the video for their mid-mount motors you can see Bafang pretty much assembles the whole product but for their hub motors it seems like there is minimal assembly of bought in parts. In fact in this video on the factory tour they are happy to admit the main hub motor assembly is manufactured elsewhere and that factory has a 1000 or more workforce which sounds like it could be one of the biggest Chinese motor hub factories but I don't know which factory that is.

 

[Nealh]

The Voilamart stand alone 250w hub is a geared hub , the 250/1000w kit is a switchable gearless D/D hub.

 

[vfr400]

the hassle of repairing/replacing gearing I really can't see it as a good option for me.

I keep telling you that you're reading too much rubbish on the internet instead of listening to people that actually deal with these things on a daily basis for over a decade. Even our forum member Cwah wasn't able to destroy the gears on his tiny high-speed 36v Q100 when he ran it at 48v with 20 amps at 30 mph and used it as a moped in the stop-start London traffic.

I think in the last 10 years, there's been maybe three or four forum members that destroyed their gears, and they were probably all because they left their bikes outside in the rain for ages to make them go rusty.

Have a look at this thread, where a forum member bought a 1000W Cyclotricity, which has basically the same motor as the Voilamart kit, but with a better control system. He wasn't very happy with it, so on our advice he bought a 250w Oxygen that was quicker than the Cyclotricity, gave much longer range, was a much nicer bike to ride and didn't shake to bits. He'd done 7,800 miles on it at the last count in June, many of those miles on rough tracks. No replacement gears!

Oxygen Scross MTB ongoing review

Took delivery of my new Oxygen S Cross MTB. Ordered from e-bikes direct. Took me a long time to decide on this one as my next bike, which will be used mostly for commuting up to 40 miles a day, 4 days a week. Hopefully it will live up to my hopes an expectations. Slap bang in the middle of a...

www.pedelecs.co.uk

 

[Woosh]

I think in the last 10 years, there's been maybe three or four forum members that destroyed their gears, and they were probably all because they left their bikes outside in the rain for ages to make them go rusty.

I can concur.
All the gearboxes I replaced have invariably been damaged by rust, nothing else.

 

[Bonzo Banana]

I keep telling you that you're reading too much rubbish on the internet instead of listening to people that actually deal with these things on a daily basis for over a decade. Even our forum member Cwah wasn't able to destroy the gears on his tiny high-speed 36v Q100 when he ran it at 48v with 20 amps at 30 mph and used it as a moped in the stop-start London traffic.

I think in the last 10 years, there's been maybe three or four forum members that destroyed their gears, and they were probably all because they left their bikes outside in the rain for ages to make them go rusty.

Have a look at this thread, where a forum member bought a 1000W Cyclotricity, which has basically the same motor as the Voilamart kit, but with a better control system. He wasn't very happy with it, so on our advice he bought a 250w Oxygen that was quicker than the Cyclotricity, gave much longer range, was a much nicer bike to ride and didn't shake to bits. He'd done 7,800 miles on it at the last count in June, many of those miles on rough tracks. No replacement gears!

Oxygen Scross MTB ongoing review

Took delivery of my new Oxygen S Cross MTB. Ordered from e-bikes direct. Took me a long time to decide on this one as my next bike, which will be used mostly for commuting up to 40 miles a day, 4 days a week. Hopefully it will live up to my hopes an expectations. Slap bang in the middle of a...

www.pedelecs.co.uk

Surely the manufacturer stating the weight limits of the hub is not rubbish it is critical information to make an informed choice. There are a huge number of sellers of replacement gears on ebay and aliexpress some of which with very high sales. Many so called expert sites for hub motors clearly state a shorter lifespan for geared hubs as is to be expected surely.

The first hit on google for direct drive vs geared hub motors is this site which echoes the same basic information as many other sites.

Geared Hub Motors Vs Gearless Hub Motors

www.ebikeschool.com

Lets not get too rude and abusive here clearly there are many contrasting opinions and many have a commercial interest in selling a specific product. I've looked around from many sources but lets not forget the manufacturer itself clearly rates direct drive motors as stronger hence a weight limit that is double that of a geared motor hub. Same company/manufacturer (I assume) with 2 very different weight limits.

I've read forum postings where the writer states in strong terms that direct drive is stronger being a larger scale motor with less moving parts.

Another web page here compared both types of motor in the real world and then some comments below where 2 people with geared hub motors have had them fail.

Geared Hub Motors vs Direct Drive; BMC vs Crystalyte

Geared Hub Motors and Direct Drive Hub Motors offer unique benefits and drawbacks. Comparing engineering specifications is helpful, but road testing finished E-bikes really shows the personality of…

www.electricbike.com

So I'm looking at information from many different sources to get the full picture. Twice the weight limit and 3x the torque is important information when considering the options.

 

[Woosh]

Lets not get too rude and abusive here clearly there are many contrasting opinions and many have a commercial interest in selling a specific product.

I sell bikes and kits, so let me explain why direct drive is not a good choice for a commuter bike conversion.
1. it has to be street legal
2. it has to climb hills with minimum effort for the rider
3. it has to be economical on battery otherwise you'd have to carry a heavy and expensive battery

Most direct drives are not street legal. Look for a 250W direct drive, you won't find it on amazon or ebay. You will need to get it made to your specs.
Most direct drives have very low yield at under 10mph. Take the Crystallite 3540 for example. This is a standard design, as old as the industry itself, the yield at 10mph is 60%, 40% of the battery goes into heat. When you hit a 10% hill, to ride at 10mph, an average rider will need 33NM torque, you need about 440W from the motor plus 100W pedalling, the battery needs to supply 733W. That is more than most batteries you find on factory made e-bikes can supply. Therefore, 10% is about the practical limit of gradient that is suitable for the kind of 1000W direct drive kits you get on ebay and amazon.
https://www.ebikes.ca/tools/simulator.html?axis=mph&grade=10

If you have a gearbox, you have 3 advantages.
1. no cogging. This is the sticky effect when you ride without power on a direct drive. The gearbox has a clutch which only engages if the motor goes faster than your speed.
2. your motor torque is multiplied by the reduction ratio.
If your motor can produce 10NM without the gearbox then with a gearbox whose reduction ratio is 1:5 (like the Bafang SWX02) then the wheel gets 10NM * 5 = 50NM.
3. lightweight and more efficient on hill.
If you go with the same bike up the same 10% hill with a geared hub like the Bafang BPM or SWX02, the yield at 10mph is 66%, 34% turned into heat, 10% more efficient on battery.
https://www.ebikes.ca/tools/simulator.html?axis=mph&grade=10&motor=MBPM

You can see why people pay £30 extra for a hub gearbox, £100 extra for a mid drive gearbox.

 

[Nealh]

All I can say is the forum have given Op answers and advice leave it at that and let Op get the D/D hub he so wishes and then see if he comes back again for more advice if it fails to deliver or manage what he wants it to do.

 

[stevefizz]

Hi guys thanks for all the advice.
Like you said its a bit primitive. I did 20 miles today used about 55% battery doing about 15 mph most of the the time. Its seems simple so hopefully reliable. My only issue was the unpowered rolling resistance. Just wondering in theory would the 250w motor have about half as much as a 500w motor? i guess it comes down to pros and cons you get more power to get up the hills but get more unpowered rolling resistance.
Thanks again
Steve

 

[vfr400]

500w is the rating of the kit, not how much power it gives. Some 250w motors give substantially more than some 500w motors.

How much power your motor actually gives you depends on its efficiency and how much the controller feeds into it. Its efficiency is very dependent on the speed its turning.

It's complicated and not very intuitive how the power works. It would be much better if you say what you want your kit to do, then we can advise you what you need. I can almost guarantee that you will not be happy with one of those 500w Voilamart kits. The 1000w ones are better, but you need a high performance (expensive) battery to provide the power that the motor needs to come alive. With either the 500w or 1000w kit, you end up with a very heavy bike that you cannot pedal without power.

 

[chris_n]

Hi guys thanks for all the advice.
Like you said its a bit primitive. I did 20 miles today used about 55% battery doing about 15 mph most of the the time. Its seems simple so hopefully reliable. My only issue was the unpowered rolling resistance. Just wondering in theory would the 250w motor have about half as much as a 500w motor? i guess it comes down to pros and cons you get more power to get up the hills but get more unpowered rolling resistance.
Thanks again
Steve

A 250w geared motor has a clutch so no rolling resistance from the motor.

 

[stevefizz]

I dont think its a deal breaker. it feels like im helping the motor where as with Suntour motor it was the other way around which felt more like cycling if that make sense. This was always going to be MK1

 

[Electricbikeman]

I dont think its a deal breaker. it feels like im helping the motor where as with Suntour motor it was the other way around which felt more like cycling if that make sense. This was always going to be MK1

I have been running a violamart 1500w hub with 20ah Lipo.
Its heavy but wow is it fun.
Done over a 1000miles from road to forest trails. Change the gearing to 53x11.
Perfect match. Lots of torque and has been bullet proof. I run 15s on the standard controller.