[Closed] E-bike conversions: hub v bb?

HUb motors are the easiest to fit. Fine for the flat and commuting. BB mount kits are better for hills because they run thru the bikes gears so they remain at more efficient speed when climbing

Front wheel motors can slip. Rear wheel motors are fine.

So your choice is between ease of fitment - Front wheel easiest, hub hardest V efficiency of use - BB mount is most efficient

BB mount means pedalling always required, hub means you can take advantage of the loophole that lets you just use the throttle !

EWrrmm wrong. if its being fitted now you have to pedal. Older kits both BB and hub could have a throttle. NO distinction in law between hub or BB

There's an advantage that a hub motor shouldn't burn out on steep hills when you run out of gears where it's possible to overload a bb mounted one if your cadence drops too much and the controller tries to put too much current through the motor.

Having said that you could probably do the same to a hub given a steep enough climb, but it should be designed to have enough power to keep it moving and prevent that.

Kits vary from simple motors in hubs that just output 250w as long as you pedal (or press a button of illegality) to torque sensing ones that add to your pedaling proportionately, the features of any particular kit affect the feel of the assistance more than where it's mounted.

Tempted to put a mid drive kit on my ofo to allow it to tow a trailer easily. Either that or I wondered if a motor hub would fit too the trailer which could have interesting consequences to the handling!

middrive, bottom bracket is better for hills. bafang being the obvious.

Problems you'll get firstly are chainstay clearance, on the drive side of the the diameter of the bbs02 is about 110mm, so you need the space to fit that tight up against the frame, it curves into to about a 90mm diameter so there is a bit of wiggle room there.

But really you can't convert every bike.

2nd consideration if you can fit that is your bb width, the bbs02's are only really made of 68mm bottom brackets, so if you do put it into a 73mm bb, you'll need to offset the no drive side, and extend your Q factor a bit. I like the width myself, you can get offset crank arms, or a 20mm pedal extender on that side works.

3rd consideration you'll have is where you are going to put your battery. On a hardtail it's easy just fire it on the down tube and make sure you've got space(I got the dimensions of the battery and made a cardboard cutout to check before I bought). On a full suss, generally it looks a complete pain. On my hardtail I drilled and extra 2 water bottle holes in the frame so I've 4 attachment points on it aswell. On a full sus, I guess you could mount it upside under the downtube, but tbh, I'd expect that eventually rip out of the frame with any kind of abuse, so don't really fancy the idea. Obviously road bike should be fine. just check the battery will fit in the frame.

4th consideration on the mtb is where the motor will go, if you've a bendy join at the bb on the down tube the motor is going to point straight down. Obviously not good for clearance from rocks etc.

As for the wisdom of converting a road bike, I wouldn't, you don't really need it.

I basically separate my cycling these days, mtb is battery powered, road is self powered.

Guess if you are using it as a commuter, then maybe but for that I'd just convert a hardtail, more comfy than a road bike.

I bought my stuff from em3ev.com and would recommend them. Hand an issue with the motor when I first bought it, and they replaced the controller on it FOC. You're buying from china, but they had a guy in london I just sent the motor to to fix the issue, which was decent.

ultimately the bafang stuff is decent, but if you have a go on a standard emtb these days, you can tell it is just a better system over all. But the bafang is decent.

DIY bolt on conversions are all shit

buy a mid motor complete bike with a good motor that senses torque, cadence and speed delivering smooth intuitive assistance.
for commuting, a shimano mid motor hardtail with slicks is ideal.
for actual road. buy the lightest mid motor Eroadbike you can afford.

Oh.. and derestrict them. 15.5mph is a stupid assist limit for the road. (it's 28mph in the states... which makes a lot more sense)

geex

Member
DIY bolt on conversions are all shit

G overstates are per. 😆 They may not be as good, but if you've a bike kicking about, you can get a conversion happening a fair old whack cheaper. That is the main attraction.

(it’s 28mph in the states… which makes a lot more sense)

It's variable state to state, most are 20mph, some go up to 30, some take the northern ireland approach.

I've been considering this for a little while for my Big Dummy. Still undecided so currently on leg power

Hub mount feels like an easier solution, mid mount like a better solution. then faffing about with something with power like a BBSHD to something with a 250W limit like a BBS01. Not that fussed about going quick, just want assist to help with heavier loads like kids/shopping/cargo on inclines. It's fine on the flat

YOu have riden all the different conversions Geex? I have ridden quite a few different conversions and and also most of the types of fully built bikes.
The best of the conversions ride 99% as well as a steps or bosch and better than some of the full builds I have ridden. A crap cheapo conversion is crap. the key thing is torque sensing. thats the key factor for ridability IMO

The torque sensing and the like will help no doubt if you are into techy up hills and the like, still get on fine with the bafang though, the 9 assist levels, mean I just do manually torque setting and adjust the power to suit as I go.. But really, 95% for the time, you are just winching yourself uphill to get to the top, how sophisticated does that winch need to be is a question to ask yourself.

Ultimate point is if you've a decent hardtail kicking about, you can(usually, assuming motor and battery fit) convert it for much cheaper. Full sus is doable but harder.

If don't have bike, just go out a buy an ebike, don't do a conversion.

The advantage of torque sensing is you do not need to adjust anything or adapt your riding style. I agree that you can manually do it via assistance levels. Mine is used as a utility bike - its just nicer to have the power the motor puts out proportional to the effort you put in.

No you haven't TJ
The "best" conversions do NOT ever ride as well as a well designed mid motor complete bike/frame.
You are not someone I'd ever listen to on advice about bike handling. and neither should anyone else.
you know fine why.

You shuld have a wee shot of mine. Nowt to do with handling - all about how the motor responds.

I did not say "well designed mid motor mounting" I said fully built bikes. Not the same thing

Have you ridden all possible conversion kits? Obviously not thus you cannot know how they ride.

I really think yo would be suprised by a ride on mine. the motor power delivery is 99% as good as a bosch or steps.

You shuld have a wee shot of mine. Nowt to do with handling

Please stop dishing out poor idiotic advice.

[img] [/img]

Ignoring Geex and to go back to the OP

the best setup is a fully built bike with steps / bosch or a similar BB motor. Next best is a bb mount kit with torque sensing. Next best is a bb mount kit with cadence sensing. HUb motors are a poor relation altho the best of them torque sense as well - but if it ( as one fully built not kit bike I rode)_ has multiple chainrings it thows the torque sensing out. as yoiu have more torque on the smaller chainring

Hub motors are much easier to fit. Front wheel motors are not as good as rear wheel motors but are easier to fit

Finally - on a road bike a legal ebike kit or full build only really helps on hills.

That's not ignoring me TJ.
You've followed my advice to the letter.
thanks for your cooperation
😉

There was an article in the recent CTC mag about electric road bikes. What surprised me was that both the bikes on test had rear hub motors. Not sure why. Guess I’ve just got used to eMTBs which all seem to be BB systems.

I can see that BB mounted makes more sense for an MTB as you want to maximise the ratio of sprung to unsprung mass, but I guess it’s less clear on a road bike. The (claimed) advantage of the hub mounted option seemed to be that it was lighter (both the bikes were “light weight” eRoadBikes) and I think there might have been something about less drag with the motor off as well. I know the reviewer said something about them feeling like normal bikes with the motor off.

Anyway, hope that’s some help. As you were.

Yeah. but rear wheel drive means weight distribution becomes really poor which affects handling massively. Most road/commuter Ebikes are sold to folk like TJ who don't really understand how to handle a bike well in the first place. nevermind the extent moving a load of weight to one end negetively affects it's handling. 😉
Quite a few current mid motors have no drag and a few mid mounted systems are now a lot lighter. (at the expense of torque/power and range tho)

I recently bought a Trek Conduit from Rutland Cycling for £1299 (1/2 price) - id looked at Bafang and Tongsheng (torque sensing) mid drive conversions but the motor+battery+import duty etc+value of the bike to convert meant the Trek was pretty much a similar price but I ended up with better integration and a legal* bike.

https://www.trekbikes.com/gb/en_GB/bikes/hybrid-bikes/electric-hybrid-bikes/conduit/conduit/p/17044/

*I chipped/hacked the software after a week as the 15.5mph limit is unworkable
https://singletrackmag.com/forum/topic/ebike-commuting-5/

So not legal so that argument is null

So not legal so that argument is null

It was legal as bought and the same legality as any other 250w/15,5mph conversion or bike. I think I was saying that as good as a conversion can be I dont think they can beat the integration of a full off the shelf system/bike. Conversions win on price compared to a bike unless you can get a decent discount on an ebike.

BB mount motors have two main advantages in terms of power delivery. firstly as they work thru the bikes gears the motor is kept spinning in a better speed range at low speed so gives its power more efficiently ( grinding a motor at low revs high power draws a lot of amps and overheats)and secondly if torque sensing then the torque sensor is not confused by the gears as it is with a rear wheel sensor

Awaits Geex telling me I am talking shite again.

The kits cannot beat a full build BB mount - but the best of them are within a whisker of being as good.

No Teej.
I'll only tell you you're talking shite when you ARE.
the only thing you've got wrong about decent mid drive units is the torque sensor works WITH the speed and cadence sensors and uses software to deliver smooth torque/power curves. cutting in and out more subtly than your shitty bolt on things. 😉

your whiskers must be a lot thicker than mine

Have you ridden a high quality mid drive conversion? almost indistinguishable from a step or bosch.

Ok.
Now's when I'll be telling you you're talking shite.

It was nice while it lasted

I guess your e-bike back in for warrenty again .

So Geex - have you ridden a high quality torque sensing conversion?

Tj, not to be antagonistic like geex but what high quality torque sensing mid drive do you have in mind? All the bafang ones I know of are cadence sensing (bbs02, bbshd) except their higher end Max series that only comes on prebuilt bikes since it needs frame modifications.

Mine is a sunstar so3- but no longer made as it was too expensive compared to a bosch / steps bike.

Tongsheng do one I believe and I think there are others but as its several years now since I did the research I am not sure of the names. There is also some stand alone torque sensors that can be added to some kits even mid mount bafengs I believe

Its a fast moving area of development and my knowledge may be out of date

In the STW recommend what you got yourself I’d go for this Here For the road bike. The controller is built into the battery case so it makes for a neat conversion. 350W so not legal, but equally not crazy powerful. It will happily assist up hills or to 21-22 mph on the flat if you change the speed settings. If you don’t fit the throttle you can get away with not changing your brake too.

I wouldn’t use this for a mtb though. As others say you need a mid drive for that.

Yes TJ
A Bafang
it wasn't even on a par controlability/assist wise with a yamaha mid motor. which are neither smooth nor intuitive compared to an E8000. I certainly wouldn't ever consider one for an Emtb.

You're recomending I try motors you yourself haven't even tried and admit to having little to no knowledge of so what exactly is your point?

So you haven't actually ridden a torque sensing mid drive kit such as the one I have- much as I thought.

Caampgareth - I forgot the pendix which is a high quality BB mount torque sensing system. Perhaps the best available now https://pendix.com/

Geex - yes a bafeng is simply controlled and therefore not nearly as good as the full build bb mount type. But they are not a "quality torque sensing kit"

A Torque senser is IMO essential but it is only one part of what makes for good control. The software and how it uses the torque, cadence and speed data to deliver assistance is what really matters.
I'd be incredibly surprised if your "no longer made" system is anywhere near as controlled as a regularly updated and tweaked current system as fitted to complete emtbs.
eg E8000 or Brose S mag.

Can we see your bike please?

Well you really would be surprised then. Because of the torque sensor and the sophisticated electronics ( although I opted for the basic kit its still quite sophisticated) It really does ride well. almost as good as the modern bb mounts for full builds. the trouble was that made the cost high so the market for it shrunk and it was a small part of a big manufacturer so they simply dropped it.

[url= https://live.staticflickr.com/1903/31218869738_bf86f294df_b.jp g" target="_blank">https://live.staticflickr.com/1903/31218869738_bf86f294df_b.jp g"/> [/img][/url][url= https://flic.kr/p/PyGSjN ]DSC_0600[/url] by [url= https://www.flickr.com/photos/25846484@N04/ ]TandemJeremy[/url], on Flickr

TJ it's unlikely your 8 year old motor will match up to the latest tech these days. 😆

Might do if you only use it for a utility bike on the road, but tbh, a bafang would be perfectly fine for that. You'd really need to stick your motor and battery on a decent mtb and take it off road in anger to find out.

tbh, as I mentioned earlier, as a winch the bafang is sound, i think youse are all a wee bit too precious on your torque sensing, it's pretty easy to use your left thumb to adjust power! 😆

Bike set up and capability are far more important than the motor.

I think geex should go and have a ride on TJ's bike 🙂

I think that Geex should stop telling other posters that their advice is rubbish when his advice is to get an e-bike and de-restrict it .

Ramsey Neil

Member
I think that Geex should stop telling other posters that their advice is rubbish when his advice is to get an e-bike and de-restrict it .

Why not derestrict? The 15mph restriction is silly.

OMG!

you've bolted a motor to your 20yr old titanium Raleigh XC frame? You're a brave man ... sorry. did I say "brave"... Silly me. What I actually meant to say was "foolish".
I honestly thought all of those had snapped a decade ago 😉
Good to see you've Teej'd the **** out of it too with massively high stem and 60mm too long fork and as large a front tyre a feasably possible so it's going to handle awfully motor or not. Why not tho? All your bike set ups are a mess. It seems to be your special power 😛

Yes. I'll take you up on the offer to try it. PM I can easily pass yours in the evening a few nights a week. I'll bring my shitty 2019 E7000 powered 150mm Emtb hardtail to compare.

* I genuinely do think the E7000 is shit compared with the E8000 so your home made bike should absolutely blow it away

hmm..

Why not derestrict? The 15mph restriction is silly.

Then buy a motorbike .

naw.

TJ it’s unlikely your 8 year old motor will match up to the latest tech these days. 😆

Might do if you only use it for a utility bike on the road, but tbh, a bafang would be perfectly fine for that. You’d really need to stick your motor and battery on a decent mtb and take it off road in anger to find out.

This ^^

But NOT this v v

i think you'se are all a wee bit too precious on your torque sensing, it’s pretty easy to use your left thumb to adjust power! 😆

While riding technical off road trails agressively?
er... think about that a little harder, eh?

Without a torque senser along with the other sensors and software to calibrate output based on the data off road rear tyre grip/control would be a ****ing lottery.
good luck sorting that out with a thumb lever.

then buy a motor bike

We already have. Do keep up!

what's that? oh... you can't?

nevermind

see you tomorrow

Well I've not died yet! 😆 so there is that!

Ultimately, you just get used to the power output however it's set. Being honest, the default mode is 9! 😆

Don't disagree torque sensing is better, just not £1.2k worth of better! 😆 Plus the extra for the 350wh of extra battery I got too on top of the standard 500wh!

I can live without it.

You can also fiddle with the software, my settings don't ramp as fast as my brothers for instance. So it is better controlled.

Where did you pluck the £1.2k figure from?

its not in that trim now!

geex

Member
Where did you pluck the £1.2k figure from?

Well I already had the bike, so the conversion cost me £850 delivered form china (750w bbs02, and 850wh battery). A reasonable hardtail probably starts about £2.2k entry level these days...

I just replaced the fork and front wheel on my bike for about £150.

So about £1.2k that I don't really have (well I did have it but I just bought a road bike for that! :lol:).

Granted the 1.2k would get me an updated bike, torque sensing with better geometry, bigger wheels, but a lesser battery. But I've bought in stages, didn't have all the cash at once, and I wanted the road bike to supplement the ebike.

That's my bike purchasing done for the next 5 years anyhow, it's all just about maintenance now. In 5 years time might think about a new purchase, most likely a full sus emtb..

Conversions make complete sense if you've already got a bike kicking about.

While riding technical off road trails agressively

The op is unlikely to be doing this on his road bike is he ?

Having ridden a bosch I can see it's merits off road for smooth delivery.

As seosamh says as a winch the bafang works just fine on the road.

It's a bit like saying you need a Ferrari to go to the shops when a Skoda will do

A reasonable hardtail probably starts about £2.2k entry level these days…

E hardtail?
Nah a little under £2k got me a mid level E7000 504wh 2019 Alu E hardtail with modern geometry. By mid level I mean a 150mm rockshox fork, novatec/WTB tubeless 27.5 boost wheelset, Maxxis rubber, Decent level finishing kit, Deore 1x10 drivetrain, 150mm dropper, the new 4 pot shimanos.
The non Ebike version of the same bike is only £900ish but it has a few entry level parts (Suntour chainset/basic shimano brakes etc.)
An E7000 motor retails about £900 and the battery about £700, display £150 controller £70 and charger £150 so it felt a no brainer for me.
Chucking £850 at a chinese motor to stick on an old shitter seems ludicrus to me.
ruining a good bike by adding one even more so.
I get that you wanted one cheap though.

When I built mine there was no off the shelf e-cargo bikes availible in UK.

an E bike thread on STW is rarely ever about the good intentioned OP after the first page Tez.
...and if you're going to bring Ferarris and Skodas into it

😉

I personally find riding motors that just assists based on cadence pretty horrible even on road. Doing it every day I'd absolutely hate. They just feel too disconnected from actual riding to me.
Fine if you disagree.

My conversion's on a 2011 genesis core 40, 26". Decent enough bike, got 1x11 slx on there, 100mm brand x dropper, just stuck on a 140mm sektor RL on it, and it's 2.4 high roller exo I've got on there, slx front brake, 203m, and original deore 180mm on the rear.

It's not really an old shitter, getting on a bit, aye, but, it's still a perfectly capable bike. There be no ruining happening. 😆 Plus I do always have the option of converting back should I wish too..

Most of the cost went on the battery tbh, 850wh, is immense.

Tips the scale at 22kg.

Why did you want a cargo bike?
Genuine Q.

Moving stuff about seemed a better use of an e motor than saddling my mountain biking with.

PLus shopping and moving jnr about.

Perfectly capable of course. But sorry. I'm afraid a 2011 26" genesis core would now 8 years later be described as an old shitter in the grand scheme of things. You could probably pick one up for around £150-200 on gumtree. Bigger issue here is possibly having an alu XC frame which was never designed to have 10kg of battery and motor bolted to it. Especially this late in it's life.
Why did you go for 850wh BTW? for super long rides or more bed/pub time and full torque everywhere?
504wh is more than enough for road/commuting use on mine and will get me 50 miles+ in eco easily or about half that averaging 20mph+ in boost the entire time.
mine tips the scales at just under 20kg with mudguards, bottle cage, tools/Co2/tube

Fair enough.
(belated) Congrats on the wee one.

Willing to accept the old shitter tag, it is well walloped in! 😆

Really weight wise, there really wasn't much difference in battery tbh when purchasing, so I just went for the biggest option as it was only adding a little more weight.

Lets me batter into the hills with little thought to battery consumption really. which is great, 30/35ish miles easy enough. Yet to run out, though I've been close, obviously you can run it down faster more climbing. Keep meaning to head over to the Kilpatricks and just do loops of that big hill to see what kinda height is achieve-able, as that's always the biggest drainer.

It would go for a silly amount of miles if you set it up as a commuting machine with faster tyres. Never actually tested that.

As for the strength of the bike, it's plenty strong enough, quite chucky up front those bikes, so no worries there.

Battery wise on an ebike, I think ideally I'd like 400wh on the bike, and then being able to have the ability to piggy back multiple 200wh batterys on. That way you could tailor the battery wieght on the bike to whatever run you are doing. Say allow capacity up to 1KW.

The TSDZ2 is the mid mount motor I've seen with torque sensing

Currently undecided but if I do go ahead it'll be fitted to a surly big dummy cargo bike. Doesn't do off road, just pottering around locally. But there are noticeable hills locally when you're loaded up

Hi folks, thanks for all your comments 😀 It’s opened up a whole new world of research. I get that off-the-shelf ebikes will usually be better, but my question was specifically for conversions.

Tja has been the only one to rise to the challenge of posting his/her conversion. Anyone else willing to post their conversion pics? Geex, I couldn’t make out whether you have done a conversion, so if not, maybe post your off-the-shelf ebike pic for scrutiny and comparison?

In terms of what bikes, it’s a 10 year old Ridley road bike with carbon stays (a thought: would carbon stays be affected by torsional twisting from the motor?). The mtb is a Trek Remedy 7, with the specific question being converting that type of frame design.

Personally I wouldn't be bolting a motor to either of those. I think it's fairly obvious why.

Mine are a Vitus E Sommet (170mm Enduro emtb) and a vitus E Sentier. (150mm modern geo hardtail)
As its primarily for road use the Sentier has a larger 38t chainring, schwalbe big Ben 2.0x27.5 tyres run at 60psi and mudguards. I run the fork really stiff but being a jumper I do the same on all my hardtails. and it is a bit American with regards to assistance limit. (about the only thing they're more sensible with).
It's 44lb all in with an empty water bottle.
Other than fitting my pref grips/pedals/saddle I swapped out the 150m Dropper to a 210mm to make it more fun to manual.

View this post on Instagram

doordonot Member

Here ye go, the oul' shitter himself!

Complete with poundshop arse protector 😆 , and sellotaped on display(need a new mount)

[img] [/img]

Ye cannae hide money

😉

[img] [/img]

Cove hummer with BBS01 and battery, bought the motor/battery kit from Brighton ebikes. I can't do the pedalling thing so it's throttle use only, not the most sophisticated set up and it has it's limitations with power delivery (either on or off really and thumb throttles are not that good) if you take it off road but it keeps me mobile for dog walking duties.

geex

Member
Ye cannae hide money

😉

It cleaned up well i thought! 😆

EWrrmm wrong. if its being fitted now you have to pedal. Older kits both BB and hub could have a throttle. NO distinction in law between hub or BB

err, wrong 🙂

"The Department for Transport has today confirmed to Pedelecs that an ordinary cycle, already ridden on public roads as such and subsequently converted to a ‘twist and go’ electric bike, will not require type approval.

The DfT further clarified that type approval ‘only applies to new vehicles, not converted ones’."

from this page :

https://www.pedelecs.co.uk/dft-pedal-cycles-converted-twist-go-exempt-type-approval/

And then in correspondence with the Dept of Transport asking if that page is correct I have this quote :

"However, my colleagues in International Vehicle Standards have confirmed
that the website have correctly reproduced their comments and the person
writing the website has understood correctly."

So if you convert a bike with a kit you can use twist-and-go throttles 🙂

Unless there is another reg that has come in since that Jan 2016 one ?

one other issue i'd mention on the bbs units is chainline, if you go below a 42, there's no dish on the chainring, so it does whack out the chain line a fair whack, with the straight 36(no dish) it is a fair old bend on the chain getting into that 46, still does go, but just something to be aware of.

The 46 is more of an emergency gear mind, but still tis good to have it.

(a thought: would carbon stays be affected by torsional twisting from the motor?

not really sure about carbon stays but they defo recommonded NOT attaching then to carbon bikes. so dunno.

Slightly at cross purposes turner guy but thanks for the clarification.