recommendation for a low cost E-bike

Electrically assisted bikes, trikes, etc.
Mark R
Posts: 583
Joined: 13 Feb 2010, 7:41pm

recommendation for a low cost E-bike

Postby Mark R » 26 Sep 2017, 11:31pm

Under £1k the choice is going to be something made in China. Not necessarily a bad thing; they know a thing or two about e-bikes but wouldn't you rather have a quality British product?

Here is the recipe for a bargain Ebike with A1 performence

1, Look out for a lightly used TGA Electorbike on Ebay or Gumtree - they come up regularly for well under £100.

2, Sell the monstrously heavy lead acid batteries to a scrap yard and spend a few £££ on a decent lithium battery pack and charger.

3, Fit the new battery pack in place of the old lead acid batteries and revel in what a capable machine you now have!

These bikes were built in Essex and are very good quality compared to a lot of the ebikes on the market today. I think they were made until the late 90s when they could no longer compete with much cheaper imports. Shame - if they had kept going a bit longer they might have ridden the wave....

The bikes have 406 alloy rims, stainless mudguards, drum brakes and 3-speed hub gearing (either Sturmey or Sachs). Most interestingly - the motor drive is through the gears using a freewheel crank arrangement. This means the hill climbing ability and the top speed is governed by the motor power and/or the bicycles gearing. Being able to apply the motor's power in a choice of 3 ratios has some excellent advantages at the expense of somewhat higher chain/sprocket wear.

Image

Ruadh495
Posts: 413
Joined: 25 Jun 2016, 11:10am

Re: recommendation for a low cost E-bike

Postby Ruadh495 » 27 Sep 2017, 11:04am

Interesting. Will the motor cope with a modern battery though? The rules in the 90s only allowed 200W max. Current regulations allow for 250W continuous, which means modern e-bikes can run peaks of about 500W. That's a big difference. Presumably the control gear is 24V, most modern batteries are 36V. Controls might be upgradable if the motor is brushless, probably not if it has brushes.

I think I'd put a reasonable quality kit on a good older push bike, rather than buying anything designed as electric under the old rules.

Mark R
Posts: 583
Joined: 13 Feb 2010, 7:41pm

Re: recommendation for a low cost E-bike

Postby Mark R » 27 Sep 2017, 1:35pm

Will the motor cope with a modern battery though?


The short answer is yes!

It is the controller which controls how much juice is fed to the motor so it doesn't know what type of battery is feeding it.

I have somehow ended up with two of these machines. One uses the standard 24v controller with a small 180w/h pack, the other is using a large 36v pack along with a modern 15a controller. They are both impressive (obviously the 36v is faster) the motors (brush type) barely get warm and I live at the top of a steep hill.


I make up my own packs from discarded power tool packs. I doubt if most people would want to get involved with that but 24 and 36v packs are freely available and should be well up to the job. Just make sure the battery you buy can deliver enough amps for the controller you are using- Li battery packs are now a well developed technology.

Ruadh495
Posts: 413
Joined: 25 Jun 2016, 11:10am

Re: recommendation for a low cost E-bike

Postby Ruadh495 » 28 Sep 2017, 10:23am

How does the performance compare with other ebikes? I remember pre-2015 ebikes as being distinctly unimpressive, but it may well be that the battery upgrade brings it up to post-2015 performance (2015 being the date of the rule change). I suppose the other question is "Is it legal?" I don't see a speed sensor; how does the controller deal with 15.5mph cut out? It can't be motor speed since it's run through the gears... Is there a "throttle"? That's OK on pedal cycle conversions, but since this has always been an ebike...

Sorry if I sound like a nay-sayer. I'm actually seriously interested; I'm considering a second e-bike for my wife and the 20" wheel shopper style would be ideal for her. Was thinking of converting a Raleigh 20 I have in the shed, but this could be a good alternative at less than the cost of a conversion kit.

Is that built in lighting I see? Another plus.

Mark R
Posts: 583
Joined: 13 Feb 2010, 7:41pm

Re: recommendation for a low cost E-bike

Postby Mark R » 28 Sep 2017, 12:35pm

I don't think you would be dissapointed with the performance. In my experience it exceeds that of a modern 'off the shelf' ebike - for hill climbing ability and for top speed.

Motor power is governed by a twistgrip. No speed sensors, no need to pedal before power is applied (I really hate this idea) - very much pre nanny state.

Is it legal? I don't know...I suppose it must have been back in the day as many were sold.

The power output from the motor seems quite modest but having a choice of drive ratios, you seem to get a lot from a little

I haven't measured the top speed but the standard 24v bike probably does around 20mph. Did the 15mph restriction apply back then? I suppose they could have got round it by gearing it really low. Or perhaps a disclaimer that 3rd gear was for 'off road use only'!

Actually it would be interesting to know the top speed - I will fit a cycle computer later and report back.

Back in the day TGA also made tricycles!Image

Ruadh495
Posts: 413
Joined: 25 Jun 2016, 11:10am

Re: recommendation for a low cost E-bike

Postby Ruadh495 » 29 Sep 2017, 11:06am

Legal top speed "back in the day" was 12mph. Perhaps with the heavy, low output lead acid batteries it couldn't do more than that. Pretty sure any upgrade which allows assist above 15.5mph will make it illegal, though it's unlikely that the authorities would take any notice unless you have an accident. Throttle only was legal (still is, in some cases), but only up to 12mph. It might be possible to argue that because the throttle was legal originally at 12mph it is still legal after an upgrade to 15.5mph, but certainly not beyond that. Lawyers would have a field day.

BTW, If you were unfortunate enough to have an accident, there would be plenty more charges available than in the case of a certain individual's brakeless fixie. An e-bike which assists over 15.5mph is legally a motorcycle and all the offences which can be applied to a motorcyclist apply.

Would the newer controller you have on the 36V bike accept a speed sensor and a pedal sensor? Controllers for brushless motors that do are widely available and cheap, but I don't know what's available for brushed motors. The way motor speed is controlled is entirely different.

Mark R
Posts: 583
Joined: 13 Feb 2010, 7:41pm

Re: recommendation for a low cost E-bike

Postby Mark R » 29 Sep 2017, 1:39pm

There is a good primer on UK and EU ebike law here:

http://www.pedelecs.co.uk/electric-bike-guides/uk-electric-bike-law/

I can't see any mention of 12mph and throttles - do you have a source for this?

Lead Acid batteries are not inherently low power - quite the opposite, they can really push some serious amps (when in good condition); think of a car starter battery. The problem with them was (and is) the monstrous weight and the fact they are fussy, easily damaged and generally don't last very long.

This is why I am convinced that upgrading old lead-acid battery tech ebikes with modern Li packs is an excellent proposition. Brushless motor tech has some benefits and has eked out some extra efficiency at the expense of the rugged simplicity of brush motors. Brushless vs brushes is hardly a game changer though (unlike lead-acid vs Li) and there is no reason not to use a brush motor drive system if you are fortunate to find one in lightly used condition

Motor speed is a function of voltage, therefore there is nothing about my replacment 24v Li pack which would increase the top speed assisted. This means that either: the bike was technically illegal when sold (probably), or it now has non standard gearing (unlikely IMO because it already feels geared on the low side).

Personally I don't concern myself with any of this. As long as the only time you exceed a typical non-assisted cycling speed is uphill, the chances of getting any hassle are minimal IMO. Of course if you have an accident then it could be a different story - best to ride carefully and stay out of trouble.

I don't know if the controller I use would accept speed sensor and/or pedal sensor inputs. I am not aware of any laws requiring a pedal sensor to be fitted - I would avoid having this if possible - it detracts from the general ergonomics and riding experience IMO.

For a controller (brushed or brushless) to be able to limit assisted speed via a speed sensor it would need to have some sort of programming interface to input the rolling circumference of the tyre. I don't think the cheap chinese controllers will have this functionality. You could achieve the same result by using something like the CycleAnalyst (link below), but then your ebike would no longer be quite so simple and rugged - a price of legality I suppose...

http://dillengerelectricbikes.co.uk/enthusiasts/grin-technologies/cycle-analyst/cycle-analyst-v3-ca3-dp-by-grin.html