Newbie question about rear hub drive on singlespeed

[closetleftie]

Hi all!

Semi-regular cycle commuter here. 12 mile commute each way, moderately hilly. Been doing it frequently for a few years. Used to take me about 45 minutes in to work, and 55 minutes back. Now getting longer as I don't have the legs that I did when I was 40...! My usual commuting bike is a Genesis Day 1 single speed. Not fixed. Single speed with a freewheel. I want to convert it to an e-bike. Rear hub preferred as I can't quite bring myself to have it obvious that I'm assisted.... I know it's just vanity! I just need to be a little bit quicker - still happy to pedal hard. The frame doesn't have a derailleur hanger.

Usually I cycle at about 100rpm cadence on the flat, 70 on the hills. So the idea would be to fit a rear hub motor (maybe one of the Woosh kits?) and then choose the gear ratio so that my cadence is 90rpm at 25kph, when the motor should cut out anyway. That way a cadence of 70rpm would be 15-16kph which is what I currently do on the steepest hills on my commute (if I ride hard).

Opinions? Is this a silly idea? And what would be a suitable kit?

 

[Woosh]

if you convert your existing SS bike with the SWX02 kit, you can flatten moderate hills at 25kph.

http://wooshbikes.co.uk/cart/#/product/uid-203-swx02-17ah/swx02-26in-rim-rear-hub-kit-with-17ah-battery

 

[closetleftie]

Thanks Woosh, that looks good! Ideal system would be 700c with a cassette so I can keep existing spacers etc to have a good chainline. It seems the XF08 kit on your website is suitable for cassettes (and the motor is lighter). Is there much difference between the two systems?

if you convert your existing SS bike with the SWX02 kit, you can flatten moderate hills at 25kph.

http://wooshbikes.co.uk/cart/#/product/uid-203-swx02-17ah/swx02-26in-rim-rear-hub-kit-with-17ah-battery

 

[Woosh]

the SWX02 is better if you weigh over 15st. It has a bit more grunt at low revs.

 

[sjpt]

We've got the Woosh XF07 front (which I think is pretty similar in power to the XF08 rear) on a tandem. Could be considered underpowered (***); but still gives a lot of really helpful assistance. We still have to pedal quite a bit on steeper hills --- moderate steepness hills here around Winchester, up to around 12%. We rely on a low bottom gear, and when our speed drops to say 6mph the hub motor is not able to give its best power either. It sounds as if you wouldn't suffer from that as you can keep up speed on your hills even without the motor.

(***) We were warned by Woosh when we bought, but nothing else available with appropriate wheels at the time.

 

[minexplorer]

Hi all!

Semi-regular cycle commuter here. 12 mile commute each way, moderately hilly. Been doing it frequently for a few years. Used to take me about 45 minutes in to work, and 55 minutes back. Now getting longer as I don't have the legs that I did when I was 40...! My usual commuting bike is a Genesis Day 1 single speed. Not fixed. Single speed with a freewheel. I want to convert it to an e-bike. Rear hub preferred as I can't quite bring myself to have it obvious that I'm assisted.... I know it's just vanity! I just need to be a little bit quicker - still happy to pedal hard. The frame doesn't have a derailleur hanger.

Usually I cycle at about 100rpm cadence on the flat, 70 on the hills. So the idea would be to fit a rear hub motor (maybe one of the Woosh kits?) and then choose the gear ratio so that my cadence is 90rpm at 25kph, when the motor should cut out anyway. That way a cadence of 70rpm would be 15-16kph which is what I currently do on the steepest hills on my commute (if I ride hard).

Opinions? Is this a silly idea? And what would be a suitable kit?

ive got an old brushless rear hub motor , controller tweaked to give19.5amps 36v.single speed 16T paired with 42T front chainring. Its set up with throttle only,tho obviously you can still input with peddling.Necessary on hills. Doesnt have any trouble getting up any hill.

I think amps are an important consideration in climbing power. Theres nothing wrong with legal 250w(15amp controllers)rear hub kits but they definately improve with a little tweaking of the shunt inside the controller.Even the smallest 6 fet controller and brushless motor can take a moderate increase in power from this

 

[Richardab]

I did it to my single speed commuter. Heres the thread.
https://www.pedelecs.co.uk/forum/threads/carbon-single-speed-commuter.31528/#post-445022
2800miles since September last year

 

[closetleftie]

Richardab, that looks really good! Particularly interested in your point about the feel of the bike when all the weight was at the back. My plan was "rack battery + Dutch style panniers to cover" but that would put all the weight on the back..... Will keep thinking before I press the button.

 

[Richardab]

I think a rack battery would be even further out back but lower so maybe marginally better. Riding in the saddle wasnt really a problem but as you know with singlespeed you sometimes need to honk it out of the saddle and that was really odd feeling. It was also a nightmare to lift as it was so tail heavy.

I would say with the SS ebike the gearing is critical, initially i was running 39/15 but i couldnt keep up with the motor and used the battery up quickly. Changed to 44/15 and its much much better, i am helping most of the time, but its hard to pull away till the motor gets going and some bigger hills are better if i honk a bit and keep my rpm and the motors in the best range, both requiring being out of the saddle. A frame mount would be the obvious solution (and thats what i am doing on my 29er conversion) but i wanted this commuter to be stealthy so the bar bag is a good compromise.

 

[closetleftie]

Interesting! I'm thinking increasingly just to frame mount the battery. I'll be swapping to a flat bar set-up anyway.

Looking at your v2: is the battery in a cradle mounted to the headtube, with the bag over the top? Makes the bag non- waterproof, no?

 

[Richardab]

I hung the battery from the top of the bars. I used a pair of these either side of the stem facing downwards.
https://www.amazon.co.uk/DSstyles-Adapter-Aluminium-Handlebar-Mountain/dp/B01HG4FB24/ref=asc_df_B01HG4FB24/?tag=googshopuk-21&linkCode=df0&hvadid=310164787656&hvpos=1o4&hvnetw=g&hvrand=16258548690820539320&hvpone=&hvptwo=&hvqmt=&hvdev=t&hvdvcmdl=&hvlocint=&hvlocphy=1006715&hvtargid=pla-348350537230&psc=1
The bag does have a few holes cut in it for the mounts and might leak a tiny bit in heavy rain but the battery is within its own enclosure anyway so the bag is more as a second defense and to tidy the wires and make it stealthy!

The frame mount is a much easier way to do it and my 29er build has the battery inside a frame bag again to give some additional weather protection and tidy it all away. See pic, not finished yet though.