Hi there! Seeking Conversion Kit advice please.

[TrevoRJJ]

Hi all pedelec experts, I am currently considering converting my old(but not too shabby) mountain bike (26" rims, total weight with rider under 100kg) for commuting with a road legal kit, purchased through a reputable supplier and looking for a bit of advice please.
I have surveyed the commute and attempted to attach the profile below.

As is hopefully clear, there is a steady climb intertwined with some reasonable gradients, which was driving me towards getting a 48v kit with decent torque, but a little concerned that the constant gradient for 2 miles would overheat a 250w motor.
Does anyone have any experience of this type of use case and whether a 250w rated motor is capable of supporting this whilst maintaining a useful service life?
I am also keeping an eye on the latest government review to doubling the 250w limit, which would enable me to get a road legal kit that should hopefully be more than adequate.
Thanks all in advance.

 

[Benjahmin]

Hi Trevor,
There are no particularly steep gradients there (west Wales resident speaking !) and should be no problem for a decent rear hub. Hub motors are optimised to give you 15.5mph. If you maintain around 50% of this speed whilst climbing there should be no problem. Any lower than this and efficiency rapidly declines and more heat is produced. I've been riding the hills around here for years and never suffered motor heating, just be prepared to work on the steeper bits.
The 250w rated power limit is just that - a rating - it's almost meaningless. A 15A controller at nominal 48v will legally give you 720w on max setting. With your own input this will be giving you 840ish watts - should zoom up that climb.
I would buy the biggest, highest quality battery you can reasonably afford. It's maximum current delivery should be at least 10% higher than the maximum current demand of the controller. Then it will be stressed less and last longer.

Have a look at the kits on Woosh. Plug and play kits with good customer service and help. He'll probably be along shortly.

I've used Topbikekit myself, though there you have to put the component list together yourself, needs a bit more thinking about, good stuff though, selling a range of Bafang and AKM motors and KT controllers.
Greenlance look to be a UK battery supplier with good quality batteries, used them myself.

 

[Peter.Bridge]

That looks very do-able to me.

Bike + rider 130kg !



Done this with nominally 250W 36V 18a XF08C (from Woosh) and nominally 500W 48V Bafang G020 15a. The controller can get a bit hot so I have introduced ventilation holes into the controller bag.

Do need to add a bit of peddling effort

This is probably the ultimate nominal 250W (48V 17a, high torque winding) hub kit for hillclimbing https://wooshbikes.co.uk/?hubkits#dwg22c-48v-kit (but need 180mm rear brake rotor)

 

[guerney]

I live on a hill. This 1.5 mile section of my route home hasn't caused my 36V 250W BBS01B conversion any issues, 3 years 4000km+ and counting. Very easy too, after firmware parameter adjustments. I'd have to travel quite a long way for a longer hill climb. I weigh 68kg and my bike has 20" wheels. Bike + rider = 92.1kg. Also, bike + rider + 90kg bicycle trailer = 182.1kg. Long steep hill climbs are nowhere near where I live, unfortunately.

 

[Peter.Bridge]

I live on a hill. This 1.5 mile section of my route home hasn't caused my 36V 250W BBS01B conversion any issues, 3 years 4000km+ and counting. Very easy too, after firmware parameter adjustments. I'd have to travel quite a long way for a longer hill climb. I weigh 68kg and my bike has 20" wheels. Bike + rider = 92.1kg. Also, bike + rider + 90kg bicycle trailer = 182.1kg. Long steep hill climbs are nowhere near where I live, unfortunately.

View attachment 56856

What's the max current set to on that ? What sort of speed do you go up that hill ? - fast enough to outrun the angry chanting mob

 

[Trevor George]

Hi from another Trevor . . I live in the hilly City of Bristol and have installed many kits for myself and friends from UK-based - Cyclotricity - as - CLICK HERE

 

[guerney]

What's the max current set to on that ? What sort of speed do you go up that hill ? - fast enough to outrun the angry chanting mob

It's been a few weeks since I went out cycling, hope my battery hasn't become terminally bored by 36V... but if IIRC about 8 to 10mph on gear 3 of 8 when the controller was limited to 15A, faster now at 18A, slower when hauling a 90kg trailer, because I have to use my lowest gear. The nutty gremlins you refer to gave chase up a lesser hill.. but I'll be a smidge faster next time

This is a 3 mile section of my route home that night, beginning with gremlin chase hill. My speed in km/h is visible on the speedo. 15A, 100% "Keep current". There are more hills home before those (at lower altitude) and beyond those to a higher altitude, all easy.





Here's 5 miles of that route:

 

[saneagle]

Nobody has ever burnt a motor in normal use, so you can forget about that. I don't see anything exception in your ride or your bike. Any 250w hub-motor kit should manage it easily.

 

[Peter.Bridge]

Hi all pedelec experts, I am currently considering converting my old(but not too shabby) mountain bike (26" rims, total weight with rider under 100kg) for commuting

Just one other bit of advice - if it hasn't got disc brakes then buy another donor bike from marketplace / ebay / gumtree - they are dead cheap. Just need disk brakes (can convert to hydraulic if manual), space for the battery on the downtube and conventional (square taper) bottom bracket - makes the conversion easier

 

[TrevoRJJ]

Wow, thanks for the swift and comprehensive replies chaps, much appreciated. I did have my eye on the woosh dwg22c kit as it happens and feel a bit more confident that something like that would do the job!

 

[TrevoRJJ]

Just one other bit of advice - if it hasn't got disc brakes then buy another donor bike from marketplace / ebay / gumtree - they are dead cheap. Just need disk brakes (can convert to hydraulic if manual), space for the battery on the downtube and conventional (square taper) bottom bracket - makes the conversion easier

My bike does only have rim brakes, but as I'm not going to be blasting much over 15 mph, this shouldn't be any more of an issue than the bike without a motor, no?

 

[Woosh]

My bike does only have rim brakes, but as I'm not going to be blasting much over 15 mph, this shouldn't be any more of an issue than the bike without a motor, no?

You will go faster when assisted, you also need to allow for the power of the motor that may overrun a little time when you brake. The end result is V-brakes at the front is not good enough. They will wear quickly, not just the rubber but also the aluminium braking band on the rim.
Best to have at least front disc brakes.

 

[guerney]

Nobody has ever burnt a motor in normal use, so you can forget about that. I don't see anything exception in your ride or your bike. Any 250w hub-motor kit should manage it easily.

With a 15A controller, would a 36V hub motored bike struggle along that route with a combined weight of 182kg? I think it'd take a far fitter and stronger cyclist than me with undamaged knees. With my mid-motor, I do that and steeper (but shorter, on short steeper hills) with just 36V and 15A while expending comparatively little effort. There'd be even less effort after changing my 52T chainwheel for a 42T. Of course someone with a hub drive could manage that with a 48V 22A controller, and a more expensive battery. I note what you said here:

https://www.pedelecs.co.uk/forum/threads/looking-for-an-alternative-to-swytch-and-would-appreciate-some-advice-in-conversion-kits-general-discussion.45712/page-3#post-686768

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.

This sort of thread is asking for a hub vs mid debate - if it turns into one of those, I'll be avoiding it. My mid-drive conversion is doing what a 36V 15A hub motored 20" wheeled bike can't do, not with me riding it anyway, with my current cheap battery.

 

[guerney]

My bike does only have rim brakes, but as I'm not going to be blasting much over 15 mph, this shouldn't be any more of an issue than the bike without a motor, no?

I been getting through rim brake pads a lot faster!

 

[Peter.Bridge]

My bike does only have rim brakes, but as I'm not going to be blasting much over 15 mph, this shouldn't be any more of an issue than the bike without a motor, no?

My first conversion had rim brakes. I think you will use it much more than you think and it will be a source of constant annoyance having to faff around adjusting the brakes, replacing pads - also as Woosh said it wears the rims - for £50-£100 just get a second hand bike with disk brakes - there's loads around. The only issue is if you are going for the dwg22c I think it needs 180mm rotors (I think you can upgrade from 160-180 mm rotors reasonably easily ?) If that is the profile of your rides I think the 48v dwg22c kit is probably overkill, (but you could go on holiday to the Alps and borrow guerney's trailer)

 

[TrevoRJJ]

I do have another potential donor bike, a Whyte Hybrid road bike with discs, but wanted to keep it analogue for when I get fitter and I didn't want to spoil it's lightweight adding loads of kit. However open to other opinions?

 

[guerney]

I've been getting through rims faster too!

but you could go on holiday to the Alps and borrow guerney's trailer

The OP darn well can buy his own. I overload my Homcom beyond the official 40kg or 50kg limit, depending on who you ask (manual states limit is 40kg), but it remains intact.

https://www.amazon.co.uk/HOMCOM-Folding-Trailer-Bicycle-Storage/dp/B078W39W37

I've got the older version with larger wheels:

THE Y small, Version 2.2

16” wheels, Load bed 580 x 380 mm, incl. Lollipop Hitch, incl. Light / Flag Holder, high-quality IGUS bearings

carryfreedom.com

 

[Peter.Bridge]

I do have another potential donor bike, a Whyte Hybrid road bike with discs, but wanted to keep it analogue for when I get fitter and I didn't want to spoil it's lightweight adding loads of kit. However open to other opinions?

The donor bike doesn't have to be anything fancy - doesn't need to be super light or have fancy gears - the motor makes a lot of more expensive "features" of bikes irrelevant - this was the first thing that came up within 5 miles of me

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And that had been on the market for 13 weeks !

 

[TrevoRJJ]

I think my mountain bike has lugs on the front forks so I could probably add a disc brake to the front as a minimum.

 

[saneagle]

I think my mountain bike has lugs on the front forks so I could probably add a disc brake to the front as a minimum.

If you have the fixings for a disc brake, you should first one. You can get one of these for £20, or if you search Aliexpress, you can get it with a disc too.

GUSTAVO E-bike Brakes Disc Hydraulic Brake SM / 2PIN Plug Electric Scooter Folding Mountain Bike Power Off - AliExpress 18

Smarter Shopping, Better Living! Aliexpress.com

vi.aliexpress.com

If you're less than 80kg, you should be OK with a rim brake, though not ideal. It'll wear fast and give degraded braking. Bikes like that are cheap, before starting, it might be worth looking for a disc brake donor, then upgrade the brakes to hydraulic for £40.