Home made pedelec

Presterjohn

Finding my (electric) wheels
Sep 11, 2024
17
3
Hi all, I'm John and I live in Belfast, northern ireland. I have my own workshop in the garden and like making things. For some time I have been lookin to build my own pedelec. I would like it to be a 4 wheeler because of stability issues with 3 wheelers. However despite the regulations saying that a pedelec can have more than two wheels there still seems to be confusion over whether it can have 4 wheels. The regulations as stated on this site say it can have 3 or more wheels and there is no weight restriction. Of course I am talking about eapc's that don't need type approval or single vehicle approval or tax, registration or mot or licence to drive. What is the status of the law? Can it have 4 wheels or not?
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
6,823
3,154
Telford
The law changed 8 years ago to allow 4 wheels. Amazon and the Post Office use 4-wheel 250w trucks to deliver some of their stuff. The 250w motors in them can deliver around 3kw, which translates to be able to drag 500kg up a 16% hill. You can have as much power as you need and still be legal if you do it right.

If you need any more advice about the electrical stuff, you should give exact details of what you're building and what you want it to do.
 

Presterjohn

Finding my (electric) wheels
Sep 11, 2024
17
3
Hi, thanks very much for the helpful reply. Yes, they have these Amazon delivery vehicles here in Belfast. I haven't actually seen if they have number plates on them yet but I will try to find out. There is confusion about whether 4 wheels are allowed or not. A guy on Youtube has built a wooden pedelec [Way out west] and was told that in Eire it definitely wasn't allowed . He wrote to the minister for transport - you can do that kind of thing in Ireland- and got a reply to that effect so he had to change the design to 3 wheels. I was just thinking of buying a Yose power conversion kit 250 W for the one i want to build because I will get all the electrics in one package.
 

thelarkbox

Esteemed Pedelecer
Aug 23, 2023
1,211
371
oxon
yose kit is great for a standard use conversion, but for max performance in a 4 wheeler with the extra mass, you will want the 'biggest' motor that carries a legit 250w rating. There are some hub motors iirc bafang G60 or G20?? that while rated and stamped 250w for the eu/uk market are rated/stamped 500w or even 750w for other markets..

then the yose controller is f/w fixed so you cant configure anything beyond the metric used to display speed/distance and its only 15a iirc.. ideally you would want a controller able to drive more amps into the motor, 20a perhaps more depending on battery and motor selected.. KT brand controllers are a forum favourite.

battery wise 48v if used with a motor supplied as 36v will add a further circa 30% to both the max rpm and the torque to get there..

So shop wisely, shop once ;)
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
6,823
3,154
Telford
Hi, thanks very much for the helpful reply. Yes, they have these Amazon delivery vehicles here in Belfast. I haven't actually seen if they have number plates on them yet but I will try to find out. There is confusion about whether 4 wheels are allowed or not. A guy on Youtube has built a wooden pedelec [Way out west] and was told that in Eire it definitely wasn't allowed . He wrote to the minister for transport - you can do that kind of thing in Ireland- and got a reply to that effect so he had to change the design to 3 wheels. I was just thinking of buying a Yose power conversion kit 250 W for the one i want to build because I will get all the electrics in one package.
Eire is part of the EEC, therefore ebikes are regulated by EN15194, which was changed to allow 4 wheels. The Amazon trucks don't have number plates in UK mainland and wouldn't need them in any EEC countries nor the other countries that adopted EN15194 as their standard. N. Ireland is a bit of an anomaly because your government didn't sign up to EN15194 and the rules in place prohibited most ebikes, so some forum members couldn't use them at all unless they did the single vehicle test and registration. I don't know if that's been fixed yet.
 

flecc

Member
Oct 25, 2006
53,201
30,603
Hi all, I'm John and I live in Belfast, northern ireland. I have my own workshop in the garden and like making things. For some time I have been lookin to build my own pedelec. I would like it to be a 4 wheeler because of stability issues with 3 wheelers. However despite the regulations saying that a pedelec can have more than two wheels there still seems to be confusion over whether it can have 4 wheels. The regulations as stated on this site say it can have 3 or more wheels and there is no weight restriction. Of course I am talking about eapc's that don't need type approval or single vehicle approval or tax, registration or mot or licence to drive. What is the status of the law? Can it have 4 wheels or not?
Northern Ireland has its own Road Traffic jurisdiction,
though they mainly follow ours. The mainland UK 1983 law as amended by the 2015 law were only adopted from 13th May 2020 in Northern Ireland.

The 2015 amendment contains the permission for 4 wheels, this link is to the part you need:


See item 2 (3) b:

(b)for “bicycles and tricycles”, substitute “pedal cycles with two or more wheels”.

So you can have as many wheels as you like.
.
 
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Presterjohn

Finding my (electric) wheels
Sep 11, 2024
17
3
I've been reading about mid drive motors and can see straight away you are going to get much more power at the back wheels because it applies the power before the gearing. I don't think I quite appreciated that before.
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
6,823
3,154
Telford
I've been reading about mid drive motors and can see straight away you are going to get much more power at the back wheels because it applies the power before the gearing. I don't think I quite appreciated that before.
That's not correct. The power comes from the controller and would be the same no matter which motor you have. I think you mean torque. With a crank motor, you can trade speed for torque using the gears. Torque affects how steep you can climb. Power affects the speed you can climb.

Be careful not to focus on one advantage of a crank-drive, because that's just about it, except that the mass in the middle of the bike gives a slight handling advantage in some circumstances. Everything else is disadvantage: Cost, reliability, cost of replacement drive components, stranding if you get a problem with the drive train, crunchy gear shifting and increased frequency of shifting.

You can get enough power to climb anything with a 250w motor if you choose electrical components for the characteristics that you need.
 
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Woosh

Trade Member
May 19, 2012
20,377
16,875
Southend on Sea
wooshbikes.co.uk
Be careful not to focus on one advantage of a crank-drive, because that's just about it, except that the mass in the middle of the bike gives a slight handling advantage in some circumstances. Everything else is disadvantage: Cost, reliability, cost of replacement drive components, stranding if you get a problem with the drive train, crunchy gear shifting and increased frequency of shifting.
I don't quite agree with this reasoning. Hub motors are not so good with very steep hills or very heavy loads. Their minimal recommended speed is typically around 8mph/110RPM. Below that RPM, the hub motor will likely to overheat when hauling a heavy load up a steep hill.
I think you need first to ride your quadricycle unpowered with some load up some hill to get the feel for what power you are likely to need then come back here for further advice. You may find that crank drives like the Tongsheng TSDZ8 are going to be much more suitable for your application.
 

matthewslack

Esteemed Pedelecer
Nov 26, 2021
1,855
1,343
Think about width if you plan to use cycle paths. Width is obviously great for stability, but in various places, anything more than about 750mm can be a problem.

I'd be wanting 900mm minimum track, more if high centre of gravity.
 

thelarkbox

Esteemed Pedelecer
Aug 23, 2023
1,211
371
oxon
@Presterjohn Before you decide on any drive system or particular motor perhaps fill in the details of the expected machine, dimensions and mass without rider or cargo for a start. the rider mass (no shaming promise..) and expected max cargo mass.
Then some details on your expectations/requirements such as steepest hill you need to climb and the range you require too will all factor in on the optimum system.

Sounds like a great project and you might have just landed in a good place for support ;)

But before @Woosh and @saneagle champion their respective corners.. give them the details to work with for some top shelf suggestions. ;)
 
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guerney

Esteemed Pedelecer
Sep 7, 2021
11,403
3,240
I would like it to be a 4 wheeler because of stability issues with 3 wheelers.
I'm very much interested in seeing sketches photos or plans of your 4 wheeler.


Be careful not to focus on one advantage of a crank-drive, because that's just about it, except that the mass in the middle of the bike gives a slight handling advantage in some circumstances. Everything else is disadvantage: Cost, reliability, cost of replacement drive components, stranding if you get a problem with the drive train, crunchy gear shifting and increased frequency of shifting.

You can get enough power to climb anything with a 250w motor if you choose electrical components for the characteristics that you need.
One advantage of crank vs hub for the same jobs ie speed as well as trailer hill hauling/climbing ability, is you can use less Watts. You said so yourself.

How many amps would a legal Bafang CST rated 250W need, in order to match the Bafang BBS01B's climbing ability? Assume the BBS01B controller is limited to 15A.

I was going to convert my Dahon Espresso with a rear hub. I don't think I'll bother now. I'd get duffed up and stabbed by thugs, and my bike'd get "grabbed" on a hill.



You can run it at 48v and around 22A, It would blitz any bike/motor running at 36v and 15A on any road you're likely to encounter. There's also the Xiongda 2-speed, which is like a winch when you run it with 48v.
36V X 15A = 540W is going to be beaten by 48V X 22A = 1056W. With my cadence sensing BBS01B crank drive, I have both hill climbing ability and speed over flat road, something I'd need the apparently unavailable Xiongda Two Speed to achieve, as well as a large battery capable of discharging 22A continuously without bursting into flames. My 20" wheeled Dahon Helios P8 folding bike's chainstays are not suitable for the Xiongda, even if available.

I had to stretch my frame to 150mm to fit a Xiongda 2-speed motor. Unfortunately, Xiongda stopped selling motors direct to end users. Since then, they seem to have gone a bit quiet and you can hardly find the 2-speed motors for sale anywhere except a very expensive German seller. You could try emailing them to see if they can help. Bonnie Xiong is one of the family owners and she's always been very helpful: Bonnie@xiongdamotor.com.cn

If you want to try one of these motors, you need the special controller to go with it. I'd recommend the KT version rather than the Lishui if you get a choice. You get them from Bonnie too along with anything else you need. It used to be about £125 for the whole kit (bare motor).
I'm not saying the OP should use a mid-drive, but I do think it'd wise to design in compatibility for one.

P.S. After controller amperage limit was raised:




P.P.S. 75kg cargo (home grown heavy veg or water) + 15.5kg Homcom folding trailer + me 72kg + 22.41kg bike = 184.9kg was dragged up steep hills regularly by my bike with the BBS01B controller at 15A, with 52T >32T = 32.5 gear inches. My 20" driven rear wheel has a 23% torque advantage over a 26" wheel, where tyre meets tarmac. It'd climb faster hauling the same trailer now with the controller current limit raised to 20A = 720W, but I won't be adding more weight to the trailer because it handles too worryingly odd with any more than 75kg cargo. And because the rear wheel QR skewer might be yanked out of the dropouts again.
 
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saneagle

Esteemed Pedelecer
Oct 10, 2010
6,823
3,154
Telford
I don't quite agree with this reasoning. Hub motors are not so good with very steep hills or very heavy loads. Their minimal recommended speed is typically around 8mph/110RPM. Below that RPM, the hub motor will likely to overheat when hauling a heavy load up a steep hill.
They are if you choose the right one. Don't forget that the Heinzmann hub-motor system can pull 500kg up a 16% slope or 250kg up a 32% hill or 125kg up a 64% one, approximately. The steepest hill you'll ever encounter on a road is about 16%.
 

Woosh

Trade Member
May 19, 2012
20,377
16,875
Southend on Sea
wooshbikes.co.uk
The Heinzmann is woefully uncompetitive against the TSDZ8.
 

Presterjohn

Finding my (electric) wheels
Sep 11, 2024
17
3
Hi, thanks for all the input , it's all helping my learning curve. What I have in mind is something very like an early cyclecar such as the GN or Grafton which were very simply put together using motorcycle components. In my case I will use ebike components. The body would be thin plywood, epoxy glued together. I've built a boat using this method and the epoxy never lets go if you fillet the joints. I don't tend to make detail drawings but work from sketches. I will post any drawings I do that are presentable. I don't do CAD designing but use a drawing board if I want scale drawings. I learnt this back in the 1960's and don't see me changing.
 
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Woosh

Trade Member
May 19, 2012
20,377
16,875
Southend on Sea
wooshbikes.co.uk
Then why don't the the Post Office and Amazon use it instead of the Heinzman.
They contract out fabrication and maintenance to third party.
For one off, you can't buy their motors nor spares. Their RN111 weighs 5.1kgs and needs proprietary controllers and cabling plus to haul 500kgs, you will need twin motors. The TSDZ8 has similar helf, you can buy it and spares on the net and for a lot less. No comparison really.