How should I upgrade a bike with a coaster brake?

[paula.]

Hey everyone, newbie here. I'm looking to convert this bike to electric: https://www.chainreactioncycles.com/cn/en/van-tuyl-porter-rn3-extra-ladies-urban-bike/rp-prod199751
Ideally, I would like to keep my coaster brake. I was thinking about getting the Tongsheng TSDZ2 but I live in a very hilly area and I read a lot of posts about how it isn't the best motor for hills. I've also considered the Bafang front hub kit, but I'm pretty sure I can't keep my brake with that. I also thought about getting the bafang 8-fun mid-drive, but I know I'd have to change my brakes with that one too. Any suggestions? I just want a bike that I can get up the hills on my commute with. I don't want a 250 Watt, preferably 350 or 500.

 

[peter.c]

The coaster brake will not be an easy conversion, very poor stopping power and with no front brake a safety problem
The option to fit that bike is really only the tsdz2 coaster brake version .But my first choice would be change the bike to one with disc brakes then think about a conversion

 

[paula.]

The coaster brake will not be an easy conversion, very poor stopping power and with no front brake a safety problem
The option to fit that bike is really only the tsdz2 coaster brake version .But my first choice would be change the bike to one with disc brakes then think about a conversion

What if I just installed disc brakes on this bike? I really like this model since it's such a comfy ride.

 

[sjpt]

Looks a very nice and neat bike. I'm surprised just the single coaster brake is legal even without electric help. I think fitting disk brakes will be difficult if it doesn't have mounts; similarly V-brakes. You could probably fit a double-pivot brake using the front carrier mount on the forks.

You probably won't need extra breaking because of electric, the critical braking will be managing the hills.

Worth keeping to 250w nominal motor if at all possible so that the bike remains a legal pedalec. Most 250w motors can generate much more than that, up to 500w or even over 700w for some. A BPM front won't be ideal but is possibly the best option. https://wooshbikes.co.uk/?hubkits#frontbpmkit Contact Woosh and see what they have to suggest.

 

[Scorpio]

Hi, nice bike, I have something similar and it's very practical.
Adding a disk brake at the front isn't too difficult but you would have to use a front wheel motor as this has the fittings to mount a disc brake, expect to spend at least £75 on the extra parts.
Don't order anything yet ( more info needed from you before anyone can give you a list of the specific parts) but for an idea:

front brake disk, 160mm or 180mm diameter (£10)
front brake caliper & lever (either cable operated or hydraulic)
maybe also a mounting to fit the caliper onto the forks.
kits are not expensive https://www.ebay.co.uk/sch/i.html?_from=R40&_nkw=front+kit+hydraulic&_sacat=177808&LH_TitleDesc=0&_odkw=front+kit&_osacat=177808

new forks (must be the disc brake type), I got some last year under £30 from http://www.ebaystores.co.uk/bankrupt-bike-parts/_i.html?rt=nc&_nkw=700c+forks+disc&_sid=538207553&_trksid=p4634.c0.m14&_sop=2&_sc=1/str/bankrupt-bike-parts/_i.html?rt=nc&_nkw=700c+forks+disc&_sid=538207553&_trksid=p4634.c0.m14&_sop=2&_sc=1

Instead of changing the forks you could fit a brake adaptor (I've not used these so have no experience but £5 is cheap !) https://www.ebay.co.uk/itm/164311725319?hash=item2641bdf507:g:kDIAAOSwwCNe6dV-

Hope that gives you some options and an idea of what's involved

 

[vfr400]

Let's get one thing straight. That bike is totally unsuitable for electric conversion. To fit a front brake, you'd have to chuck the basket arrangement and/or fit new forks. Those forks don't look very standard either, so the chance of finding disc brake ones is going to be close to zero. Despite what others say, it is not possible to fit a disc brake to those forks as they have no mounting point.

If you want an electric bike, buy a ready-made one or a suitable donor with disc brakes. I'm sure you'll be able to find plenty of comfortable ones.

 

[flecc]

I'm surprised just the single coaster brake is legal even without electric help.

It is not legal in the UK and I'm surprised that Chain Reaction is selling it, they should know better.

A bicycle must have two brakes to be on UK roads:

The Pedal Cycle Construction and Use Regulations 1983, says you need two brakes by law: one on the rear wheel and one on the front.

That law applies in Belfast too where Chain Reaction are based.

In 2017 cyclist Charlie Alliston received an 18 months prison sentence after hitting and killing someone, simply because he didn't have a front brake on his bicycle and didn't stop in time, as the judge made clear:

The judge said Alliston’s “whole manner of driving” caused the accident. “If your bicycle had a front-wheel brake you could have stopped, but on this illegal bike, you could not. On your own evidence by this stage you weren’t even trying to slow or stop. You expected her to get out of your way.”
.

 

[Scorpio]

Good advice above from @vfr400 and @flecc - buying a different bike will be the easiest (and maybe even the cheapest) solution.