E bike conversion

Electrically assisted bikes, trikes, etc.
hemo
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Location: West Sussex

Re: E bike conversion

Postby hemo » 11 Feb 2020, 9:14am

reohn2 wrote:I know nothing about the Yosepower kit but in their specs linked to by Philig they claim 30Nm torque whilst Bafang mid drive claim 80Nm, Bosch and other big names are all claiming 70Nm+


You have to take the quoted Nm rating with a pinch of salt as the figures are indirect drive that has to transfer it through the drive train, hence more wear and tear on mid drive train.
I think it was Woosh bikes on Pedelecs forum who said that the Bosch torque Nm is only at the motor and that in real terms the 80 is equivalent to a hub motor having 40Nm and the 70 equivalent to a hub motor having 35Nm.
Tony at Woosh who is the tech guy has done some conversion figures and said the reason being so is the hub torque is already in the wheel central position and directly drives the wheel/gearing so doesn't have to convert the torque via the drive gear.

Another forum user on there also stated that with increase torque that Bosch and other mid drive producers claim, isn't purely down to internal gearing and says it is down to the wattage output of the drives which seem to bee increasing from the original 40/50 Nm drives.
For instance Aikema are more up front with their torque figures and for their mid drive state 80Nm/250w, 100Nm/350w & 120Nm/500w drive figures.
The Aikema128sx cassette hub motor they claim >60% Nm for the 500w geared hub, which ties in with that which Woosh quoted.
Last edited by hemo on 11 Feb 2020, 9:26am, edited 1 time in total.

reohn2
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Re: E bike conversion

Postby reohn2 » 11 Feb 2020, 9:19am

hemo wrote:
reohn2 wrote:I know nothing about the Yosepower kit but in their specs linked to by Philig they claim 30Nm torque whilst Bafang mid drive claim 80Nm, Bosch and other big names are all claiming 70Nm+


You have to take the quoted Nm rating with a pinch of salt as the figures are indirect drive that has to transfer it through the drive train, hence more wear and tear on mid drive train.
I think it was Woosh bikes on Pedelecs forum who said that the Bosch torque Nm is only at the motor and that in real terms the 80 is equivalent to a hub motor having 40Nm and the 70 equivalent to a hub motor having 35Nm.
Tony at Woosh who is the tech guy has done some conversion figures and said the reason being so is the hub torque is already in the wheel central position and directly drives the wheel/gearing so doesn't have to convert the torque via the drive gear.


I didn't know but that makes sense.
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philg
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Location: Porlock, Somerset

Re: E bike conversion

Postby philg » 11 Feb 2020, 10:23am

Agree with all the above.

To summarise my limited experience with hub motors:
Swytch bike (FWD 250W 40Nm) and Yose (FWD 250W 30Nm) - neither cope with >20% gradients but this is mainly due to wheelspin/loss of traction
Yose (RWD 350W 35Nm) easily copes with 25+% gradients on a heavy MTB.

Mid-drive units probably cope better with hills as by using the correct gear they allow the motor to spin faster, hub motor spin at the wheel speed and for hill struggles that isn't an optimum operating speed (I think)

hemo
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Location: West Sussex

Re: E bike conversion

Postby hemo » 11 Feb 2020, 5:04pm

The Yose rear hubs aren't optimally wound for hill climbing as they are approx. 280 - 300rpm hubs, this makes for inefficient power transfer when a steep hill is encountered. A better hill climbing hub needs to be < 230rpm so that less power/watts is turned to heat to make it more efficient. Ideally a hub needs to spin at about half of it's optimal loaded road speed to be in the best efficiency curve.
A 280RPM hub is approx. 23- 25mph maxed out assisted in 700c wheels so needs at least to be able to go up steep inclines at 11.5 -12.5mph. A 201 rpm hub max's out at approx. 16.5 mph so at an average of 8.5mph will be more efficient at steeper hills, if a rider can maintain that.

Going back to the mid drive vs hub Nm theories, I feel that some manufacturers aren't coming clean with actual nominal wattage used and all are being labelled 250w to be legal as I don't think any one will know how to test then correctly. Call me cynical but I think it is a bit like the emissions fiasco which VW and others claimed.

Cowsham
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Re: E bike conversion

Postby Cowsham » 1 Jun 2020, 9:03pm

What does a front hub motor do to forks? Is steel forks better? What size of head set is preferred?

theballboy
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Joined: 2 Jun 2020, 10:25am

Re: E bike conversion

Postby theballboy » 2 Jun 2020, 12:22pm

Hi, any idea if the bafang kit has torque sensor?
Im 5'11' -15stone and looking to do 10 - 15 mile a time just
stodd wrote:
Another important decision is cadence sensor (typically with front/rear hubs) or torque sensor (typical with crank drive).
Torque sensor multiplies your effort to give a more natural feel; and is more expensive. Kicks in quicker for hill starts.
Cadence sensor (actually just on/off are you pedalling) allows you to ghost pedal when you are tired,
just keep pedalling but no effort, and the motor still works. Often takes 1/2 pedal turn or more to kick in for hill starts.

Whatever you do, don't go for a cheap powerful direct drive motor; they are very inefficient, very heavy, and chew through battery.


A

theballboy
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Re: E bike conversion

Postby theballboy » 2 Jun 2020, 12:26pm

Hi, would you recommend the TDSZ then over the bafang?
Must check out the reviews on those and the aikema
Thanks
hemo wrote:The Tdsz is believed to be a better option being torque drive like the, (Bosch mid drive, not very reliable as they don't like the wet).
Aikema also make a BBS type copy which has nearly double the internal gearing ratio, so theoretically should be easier to ride unassisted if needed to.

hemo
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Location: West Sussex

Re: E bike conversion

Postby hemo » 2 Jun 2020, 10:06pm

Cowsham wrote:What does a front hub motor do to forks? Is steel forks better? What size of head set is preferred?


The torque of a hub motor can cause the drop outs to eventually fracture with ali forks even with torque arms, the sus forks in the style of the Rockshok models have not much meat/thickness to the drop out and are a poor option. On a 700c/hybrid that uses the Suntour nex style fork the drop out is meaty at about 8mm thick and some are triangulated a little these make for a strong option.
Steel is ano brainer stronger in design/material and less likely for a hubs axle to rotate with in the drop out.

hemo
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Location: West Sussex

Re: E bike conversion

Postby hemo » 2 Jun 2020, 10:13pm

The Bafang BBS is cadence sensor only.

Tsdz gives a different ride style the 48v by all accounts is like night and day compared to the 36v model, only Woosh bikes sell the 250w 48v model as a customer custom option.

theballboy
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Re: E bike conversion

Postby theballboy » 2 Jun 2020, 11:42pm

hemo wrote:The Bafang BBS is cadence sensor only.

Tsdz gives a different ride style the 48v by all accounts is like night and day compared to the 36v model, only Woosh bikes sell the 250w 48v model as a customer custom option.


THanks - wonder how the real world difference off road would compare between the 750w 48v Bafang and 250w 48 TSDZ?

Cowsham
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Re: E bike conversion

Postby Cowsham » 3 Jun 2020, 2:03pm

hemo wrote:
Cowsham wrote:What does a front hub motor do to forks? Is steel forks better? What size of head set is preferred?


The torque of a hub motor can cause the drop outs to eventually fracture with ali forks even with torque arms, the sus forks in the style of the Rockshok models have not much meat/thickness to the drop out and are a poor option. On a 700c/hybrid that uses the Suntour nex style fork the drop out is meaty at about 8mm thick and some are triangulated a little these make for a strong option.
Steel is ano brainer stronger in design/material and less likely for a hubs axle to rotate with in the drop out.



Thanks hemo

hemo
Posts: 768
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Location: West Sussex

Re: E bike conversion

Postby hemo » 3 Jun 2020, 8:00pm

theballboy wrote:
hemo wrote:The Bafang BBS is cadence sensor only.

Tsdz gives a different ride style the 48v by all accounts is like night and day compared to the 36v model, only Woosh bikes sell the 250w 48v model as a customer custom option.
http://www.topbikekit.com/high-torque-24v36v250w-discbrake-rear-motor-with-inner-controller-and-speed-sensor-p-481.html

THanks - wonder how the real world difference off road would compare between the 750w 48v Bafang and 250w 48 TSDZ?


A lot Tonsheng is about 17/18a and the 750w Bafang 25 respectively 860w vs 1200w max power output.
One is legally marked and the other isn't, the Tonsheng will be more frugal with battery usage so range will be better. Also the TS input of the Tonsheng will add a few extra miles as well.

hjd10
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Re: E bike conversion

Postby hjd10 » 8 Jun 2020, 2:02pm

philg wrote:
Bonzo Banana wrote:My point is the entry level products are mainly freewheel based which is a low grade option,

I have this on my MTB (with cassette) and despite the low price has behaved faultlessly, there is a similar 700c option.
https://www.yosepower.com/en/product/Hu ... e-110.html
I'm sure there are others but, as I reported in a previous post, the service from this supplier (on another product) has been excellent so I wouldn't look elsewhere personally.

And to answer the OP - I also live in a (very) hilly area (Exmoor) and would advise RWD.

I have a FWD system (Swytchbike) on my Spa Tourer and the loss of traction on the steepest (20%+) sections, especially in wet & leafy winter, causes an almost immediate stop and dismount, sometimes less than gracefull.
Standing on the pedals and leaning over the front causes loss of traction at the back, so that doesn't work either.

For fitter riders able to put more leg power in of course this may not be a problem, it is for me hence RWD for the MTB.

YMMV


What sort of range do you get from the FWD system? I'm looking at something for commuting, my commute is about 5 miles each way with a couple of short steep hills.

Regards,

stodd
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Re: E bike conversion

Postby stodd » 8 Jun 2020, 3:39pm

There won't be a huge difference in range between front, crank and rear systems on the same battery. Crank drive and torque sensing should both be a bit better in theory, but the difference is small. The main exception is heavy direct drive motors, especially the high power ones; they really get through battery fast (both in terms of range and longevity), and don't climb hills well either.

The Bosch range assistant https://www.bosch-ebike.com/en/service/range-assistant/ gives a pretty good idea even for non-Bosch bikes. In particular it demonstrates the huge difference in expected range depending on conditions and level of assist used. Play with the settings a bit and you will generally see 'up to' figures (lowest assist, fast bike/tyres, flat. windless, good road, light rider) are about 3 times greater than a typical rider will get in typical conditions.

You should manage 5 miles each way with some hills pretty easily on almost all ebikes except those with really tiny battery capacity. Lots of those a really lightweight bikes (light for an ebike) that assume the rider will do most of the work; so can still get a decent range.

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philg
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Re: E bike conversion

Postby philg » 8 Jun 2020, 6:26pm

hjd10 wrote:What sort of range do you get from the FWD system? I'm looking at something for commuting, my commute is about 5 miles each way with a couple of short steep hills.
Regards,


As post above, the real difference in range is how much climbing and how much e-effort you need and what capacity your battery has.

As an example, on a ride last week of 48km and 1533m of climbing, I probably had ~15% in reserve with a 470W hr battery (can't lie though, it was getting anxious towards the end due to voltage sag)
Spa Tourer with rack bag full of junk and FWD hub motor, probably 25kg all up)

(Your mileage WILL vary :) )