Road Bike Conversion - 130mm OLD - Which kit / motor?

[Slightlypedantic]

Hi Everybody,

I've been looking at a road bike conversion, but this doesn't seem as straightforward as one might think.

My daughter has a Trek Lexa road bike, XS frame size.




Thinking that it would help her up the steeper hills around Goudhurst in rural Kent, my son-in-law bought her a Swytch front hub kit and asked me to fit it. At first sight the kit looked neat and easy to install... but I soon realised :

• A 90Whr battery (yes, 90Whr!) would have very little range and is unlikely to deliver enough current to help up steeper hills. Slowing down, the motor would become inefficient and quickly drain the battery.
• The Trek front drop-outs are 9.5mm and would need filing out to 10mm.
• The washers for the 10 x 12mm motor axle overlap the lawyers' lips on the forks, which would mean filing the drop-outs 2 - 3mm deeper and reducing tyre clearance.

I've advised them to sell the Swytch kit. So, what could I fit?

Presumably any front hub motor will have 10 x 12 axle and thus the same installation problems?

An obvious choice is a rear hub conversion using, say, Aikema 85SXC as offered by Woosh* with 17Ahr battery. Whilst the battery would fit in the frame triangle, the rear OLD is 130mm and the 95SX and other motors I have seen are 135mm OLD. I'm not keen on stressing the rear triangle that much to make one fit. I will check the OLD again with the wheel out - if it measures 132mm or 133mm it might just work?
*It's shown as a "new" product on Woosh's hub motor page but for some reason doesn't appear in the list higher up?

The other option is crank drive, either BBS02 or TSDZ2B. I don't have experience of these although I have picked up some insights from this forum. Both have their attractions, but would they make a good conversion on a road bike with XS frame size? Would the BBS02 clear the front wheel? Simple (hub) is reliable...

It would be nice if a smaller, lighter battery was available, say 10 - 13Ahr, but I suspect the sizes are much the same (being defined by available bases and cases?) and the weight saving marginal. Perhaps a bag battery under the saddle or in the top of the triangle?

Would it be wise to fit wider tyres as part of the conversion? (700c x 25 atm.)

Summing up:

• How can I achieve an installation that will make a nice converted road bike, and still be nice to ride with the battery removed?
• Is a road bike the wrong starting point?
• Should we just get an older Orbea Gain instead?!

Looking forward to a diversity of views!

Cheers,
David

 

[saneagle]

If I was converting it, I'd use an AKM 100C/ Q100C motor, a KT 15A controller and whatever battery floats your boat. 36v should be fine if she's not a heavyweight, and 10ah to 12ah to keep the weight down.

Any cassette motor is quite wide, but the frame will easily stretch to accomodate it. The frame is stressed when you sit on your bike and the impact when you hit a bump is massive by comparison. If you don't want to stress the frame, you can't ride the bike.

A crank drive will fit, and will be easy to install, but you get the downside of having to be in the right gear all the time and a harsher ride with too much torque in the low gears that makes the ride jerky.

 

[Az.]

I would start fresh with another bike. Frame with disc brakes. Tsdz2 if your daughter is a keen cyclist eventually hub motor with torque sensor.

 

[Nealh]

Bafang G370 is a 10 dia axle , though one will need steel forks as no Torque arms can be fitted. My one sat in a pair of Surly DT's perfectly with no filing.
For a roadbike one wants as light as possible .

 

[Slightlypedantic]

Bafang G370 is a 10 dia axle , though one will need steel forks as no Torque arms can be fitted.

Unfortunately the forks are alloy.

 

[Slightlypedantic]

Thanks for the suggestions, everybody.

For a roadbike one wants as light as possible .

Definitely, I'll keep that firmly in mind.

I would start fresh with another bike. Frame with disc brakes.

That's probably the ideal approach, and it doesn't necessarily have to be a road bike. Before going down that road, I investigated this bike further.

If I was converting it, I'd use an AKM 100C/ Q100C motor, a KT 15A controller and whatever battery floats your boat. 36v should be fine if she's not a heavyweight, and 10ah to 12ah to keep the weight down.

Always worth listening to Saneagle

The Aikema website gives the following torque, weight and OLD ("installation width") information:
85SXC - 42Nm / 2.0kg / 135mm
95RXC - 50Nm / 2.5kg / 138mm
100SXC - 50Nm / 2.2kg / 142.5 mm

The 100SX looks an attractive proposition with significantly more torque than the 85SX for only a small increase in weight, and is significantly lighter than the 95RX, although the installation width is wider. It would also be more transferable to another bike than the 85SX, if the need arose.

The drop-outs measure 131.5mm and my spare 95RX motor (without washers) dropped in with at least 1mm to spare. (Presumably the Aikema "installation width" dimensions above include the anti-rotation washers, contrary to the diagrams on their web site.) I bolted the 95RX in position with its anti-rotation washers and I was just able to spring it in. Unfortunately, when I tried adding another thick washer to replicate the 100SX, I struggled to spring the frame apart sufficiently. (It's a extra small frame, so the seat stays are short, which may make the whole back end stiffer.) The 100SX was a good idea, but regrettably not suited to this particular bike. So it comes down to the 85SX.

I'd be very happy with a KT 15A controller, and an LCD4 to save space on the drop bars. I think the LCD4 has relatively limited functionality, so would it be wise to buy an LCD3 as well to set up the controller?

Yes, a 36V 10-12 Ahr battery should do the job nicely. A 12Ahr battery would make the whole system more transferable to another bike, so a small weight penalty may be acceptable. I'd have to look for a relatively light-weight battery of reasonable quality, and not too expensive.

Thinking about minimising weight (from my limited experience), numerous thick 10 gauge (2.6mm) spokes and (presumably) cheap rims seem to make kit motor wheels a good bit heavier than they need to be - not ideal for a road bike. Building a motor wheel with a reasonably decent rim and Sapim spokes would reduce the weight significantly and ride more smoothly. Ideally, I'd like to find find a bare 85SX motor, low speed version. No luck so far...

The rear drop-outs are shallow and chamfered at the front, so the anti-rotation washers won't have anything to push against. I'd need to fit two torque arms, but inconvenient mudguard mounting lugs on the back of the dropouts get in the way. I couldn't find a way of fitting torque arms effectively. Sadly, the risk of damage to the drop-outs effectively rules out a rear hub motor. I haven't investigated mid drive motors, as this is an area where I don't know much and would prefer to learn on my own bike rather than someone else's.

So I have concluded that my daughter's road bike isn't really suitable for conversion. I'll change her cassette and rear mech so she at least has a 34T bottom gear instead of 28T. She also has an mtb, so I'll have a look at that as a possible alternative for conversion.

This reminds me of the old joke about the Irishman who, when asked how to get to Dublin, replied "Well, if I were you I wouldn't start from here".

Any further thoughts, anyone?


It's really great having this forum. Access to good advice, different points of view, and a sounding board is invaluable. I really appreciate it. In a fairly short time I've gone from knowing very little to feeling reasonably confident about selecting, installing and setting up a hub motor kit, and avoiding at least some of the pitfalls. Thanks again, everybody.

 

[Nealh]

The only difference between the LCD4 & LCD3 apart from size is that it shows no watts output other wise is does all that the LCD3 does, there is no need to buy both unless of course one doesn't get on with the LCD4 small pads. All settings /parameters are available and uses the same process as for the LCD3.

 

[harrys]

What are TSDZ2B mid drive prices in the UK, compared to hub motors? From a power comparison, they are not as strong as a 500W hubmotor, but should compare to a Swytch. I can get a TSDZ2B kit in the USA for less than a hubmotor in a wheel plus controller/display. I really dislike filing dropouts to fit the 10z12 axle too.



The non cassette Q100H hub (AK100H) motors have a more adjustable O.L.D. dimension. First, they are 135mm, but if you fit a thinner freewheel, you can get down to 130mm.

The axle spacing is determined by bushings with a hex nut.

 

[Woosh]

My TSDZ2B has the standard 48V controller which is the same in all those advertised as 500W and 750W TSDZ2B. The difference is it is restricted to 10A continuous, 15A max. Those advertised as 500W and 750W have been programmed with higher max current. My TSDZ2B comes with a full throttle but you don't have to connect it. The other difference is mine is the only one in the UK with Tongsheng 250W labelling so as a 48V TSDZ2B, it's pretty much the only one in the UK.
The price is £385.
https://wooshbikes.co.uk/cart/#/product/uid-206-tsdz2bt/tsdz2bt-cd-kit-48v-250w-with-throttle

The cheapest quality hub solution at the moment is to start with a BBTS kit for £100 then add a motorwheel with 9-pin motor cable and a 36V or 48V battery.
https://wooshbikes.co.uk/cart/#/category/uid-6/bbts-kit
IMHO, the BBTS compares well against KT solution and Lishui solution. It has the simplest wiring, flexibility of the KT and the natural ride feel of a proper TS. The Tongsheng torque sensor needs software calibration, the BBTS doesn't.

 

[Bikes4two]

If you are happy with the look of a mid drive kit then in my view the TSDZ2 with its torque sensing system will give you a ride experience more akin to the natural feel you get riding an unassisted bike but with 'bionic legs' (as some people describe the experience).

A mid drive kit like the TSDZ2 is simple to fit (I've done 5 fit-outs now) and is much simpler than say a hub kit as the TSDZ2 controller and PAS sensor is all in the motor casing.

I have test ridden Bosch and Shimano mid drive bikes belonging to friends and the ride experience of the TSDZ2 is very similar whilst that from cadence sensing hubs is noticeably different, but still enjoyable, just not in the same way.

If you've only ever ridden hub fitted bikes and are happy with that and you are more comfortable with fitting hub motors, then fine.

As an aside, a comment up-post that said

A crank drive will fit, and will be easy to install, but you get the downside of having to be in the right gear all the time

has most definetly not been my experience in riding TSDZ2 for 2 years now but as an experienced unassisted rider, I naturally use the bike's gears anyway

and a harsher ride with too much torque in the low gears that makes the ride jerky

- again, that has not been my experience with the TSDZ2 - I'm speculating that those comments may be more akin to the cadence sensing motors like the Bafang BBSxx series?

 

[Az.]

What are TSDZ2B mid drive prices in the UK, compared to hub motors?

Depends where you buy. £220 - £500 for TSDZ2B.
Hub motors with controller are a bit cheaper. £150 - £400.

 

[Bikes4two]

My TSDZ2B ............The Tongsheng torque sensor needs software calibration, the BBTS doesn't.

Why do you say the torque sensor needs calibration? I've fitted 5 of the TSDZ2 motors now and the 'out of the box' torque sensors have been fine - is calibration essential for the 'B' varient then?

PS - I know torque sensor sensitivity does vary motor to motor and that for the purist, there is a software method for calibrating the TS, but I didn't think it was essesntial - happy to be corrected.

 

[Woosh]

When you switch on the lcd on the tsdz, the software goes through a calibration routine using the stored torque calibration value in the LCD. That is why it is recommended that you switch on the lcd when not pressing on the pedals for 2 seconds afterwards for the calibration to complete. The BBTS does not need to run calibration routine. The voltage of the torque signal is proportional to the torque.

 

[Saracen]

Hi Everybody,

I've been looking at a road bike conversion, but this doesn't seem as straightforward as one might think.

My daughter has a Trek Lexa road bike, XS frame size.

View attachment 54747


Thinking that it would help her up the steeper hills around Goudhurst in rural Kent, my son-in-law bought her a Swytch front hub kit and asked me to fit it. At first sight the kit looked neat and easy to install... but I soon realised :

• A 90Whr battery (yes, 90Whr!) would have very little range and is unlikely to deliver enough current to help up steeper hills. Slowing down, the motor would become inefficient and quickly drain the battery.
• The Trek front drop-outs are 9.5mm and would need filing out to 10mm.
• The washers for the 10 x 12mm motor axle overlap the lawyers' lips on the forks, which would mean filing the drop-outs 2 - 3mm deeper and reducing tyre clearance.

I've advised them to sell the Swytch kit. So, what could I fit?

Presumably any front hub motor will have 10 x 12 axle and thus the same installation problems?

An obvious choice is a rear hub conversion using, say, Aikema 85SXC as offered by Woosh* with 17Ahr battery. Whilst the battery would fit in the frame triangle, the rear OLD is 130mm and the 95SX and other motors I have seen are 135mm OLD. I'm not keen on stressing the rear triangle that much to make one fit. I will check the OLD again with the wheel out - if it measures 132mm or 133mm it might just work?
*It's shown as a "new" product on Woosh's hub motor page but for some reason doesn't appear in the list higher up?

The other option is crank drive, either BBS02 or TSDZ2B. I don't have experience of these although I have picked up some insights from this forum. Both have their attractions, but would they make a good conversion on a road bike with XS frame size? Would the BBS02 clear the front wheel? Simple (hub) is reliable...

It would be nice if a smaller, lighter battery was available, say 10 - 13Ahr, but I suspect the sizes are much the same (being defined by available bases and cases?) and the weight saving marginal. Perhaps a bag battery under the saddle or in the top of the triangle?

Would it be wise to fit wider tyres as part of the conversion? (700c x 25 atm.)

Summing up:

• How can I achieve an installation that will make a nice converted road bike, and still be nice to ride with the battery removed?
• Is a road bike the wrong starting point?
• Should we just get an older Orbea Gain instead?!

Looking forward to a diversity of views!

Cheers,
David

It never fails to amaze me that people just reply to a question and fail to state the law.

Remember UK law, 250 watt motor max

the 02 bafang is 500 watt ILLEGAL and will mean points on your car driving licence "when" caught, I assume you have researched the UK law ? so is the TSDZ2B lets hope you don't have an accident where the police are called, it happens, pedestrian steps out, illegal motor ............

I use

Homepage → Cogs Y Gogs - eBike Workshop Supplier & Installer

https://www.cogsygogs.co.uk/wp-content/uploads/2024/10/AQPIX9TXMKwrH68fXubUBNGkTRH6AvNf-ocjA54dPV1tlP317czUR3bi3gY_agzJ5H3XCwHGzo91C1pq5ZutJA64-1.mp4 Gweithdy beics ac beics trydan We service and repair Bicycles and Electric bikes. Cogs Y Gogs North Wales Bicycle & e-bike Workshopfor all your...

www.cogsygogs.co.uk

 

[saneagle]

It never fails to amaze me that people just reply to a question and fail to state the law.

Remember UK law, 250 watt motor max

the 02 bafang is 500 watt ILLEGAL and will mean points on your car driving licence "when" caught, I assume you have researched the UK law ? so is the TSDZ2B lets hope you don't have an accident where the police are called, it happens, pedestrian steps out, illegal motor ............

I use

Homepage → Cogs Y Gogs - eBike Workshop Supplier & Installer

https://www.cogsygogs.co.uk/wp-content/uploads/2024/10/AQPIX9TXMKwrH68fXubUBNGkTRH6AvNf-ocjA54dPV1tlP317czUR3bi3gY_agzJ5H3XCwHGzo91C1pq5ZutJA64-1.mp4 Gweithdy beics ac beics trydan We service and repair Bicycles and Electric bikes. Cogs Y Gogs North Wales Bicycle & e-bike Workshopfor all your...

www.cogsygogs.co.uk

View attachment 54962View attachment 54965View attachment 54964

Can you give an example of someone getting points on their licence for riding a bike with a BBS02? I've never heard of that happening? AFAICS, it's only scaremongers on forums that say that. The first time they catch someone, they normally give a warning, but occasionally confiscate the bike.

During the police clampdown in Coventry, only a few of the illegal riders were prosecuted for things like defective brakes and being illegal immigrants, not for riding an illegal bike.

 

[Woosh]

so is the TSDZ2B

??? if you knowinging buy a 500W or more then yes, but Tongsheng make 250W TSDZ2B too.
They have EN15914 certificate for them.
I know you don't have the TSDZ2B, but you should check the label and their website, they make 3 versions, 250W, 350W and 500W. Some sellers make slightly untruthful claims to gain commercial advantages.

https://www.tongsheng-e.com/product/75.html

 

[guerney]

a harsher ride with too much torque in the low gears that makes the ride jerky.

- again, that has not been my experience with the TSDZ2 - I'm speculating that those comments may be more akin to the cadence sensing motors like the Bafang BBSxx series?

It was before firmware setting adjustment. Mine was sold with the "Optimally jerky and awful" setting enabled - I was on the verge of demanding a refund.

 

[Saracen]

Can you give an example of someone getting points on their licence for riding a bike with a BBS02? I've never heard of that happening? AFAICS, it's only scaremongers on forums that say that. The first time they catch someone, they normally give a warning, but occasionally confiscate the bike.

During the police clampdown in Coventry, only a few of the illegal riders were prosecuted for things like defective brakes and being illegal immigrants, not for riding an illegal bike.

I suggest YOU contact any police force and ask them directly

 

[Nealh]

The only publicised case/s I have heard of someone getting points and a fine for illegal e-bike riding is one in Wales where a twist and go small bike was being used and it had no peddles. The guy was fined £350 & 6 points to a license , problem is thise things mean nothing to the yobs /idiots riding such things as they don't really care if they have a licence or not.
Even the Dalston guy wasn't prosecuted for an illegal bike when a pedestrian he hit was killed because the prosecution tried for a harsher offence which didn't stick and a jury found him not guilty.

 

[Raboa]

C washers might help if fitting a front motor.

C washers for sale | eBay