E bike project advice and help

Electrically assisted bikes, trikes, etc.
olddave
Posts: 12
Joined: 17 Aug 2018, 11:20am

E bike project advice and help

Postby olddave » 17 Aug 2018, 1:07pm

I am now retired and I would like to build an ebike as a diy project. Due to health problems I need more assist than leg power
Around where I live there are some nice small country roads but we share them with vehicles that the roads where never designed to take. So I only intend to ride on cycle tracks/paths etc. I want to be able too travel around 40 miles so I can travel to the coast and back at a gentle pace
The more I look online at the different E bike web sites the more it gets as clear as mud so I am tempted to buy a 1000w 48v 20ah duel power kit as this set up would give me the range ( I hope for ) but the batteries now become very expensive. Am I going over the top with this spec I normal do, I am belt and braces type
I understand the law about traveling 15.5 mph, 250w motor but as I will be "off road" I should be ok with the law
Any help and advice from anybody who has gone down this way or anybody who can put me on the right track to stop me from cocking it up and wasting my money I will be greatful

stodd
Posts: 49
Joined: 6 Jun 2018, 10:24am

Re: E bike project advice and help

Postby stodd » 17 Aug 2018, 5:03pm

Technically a 1000w kit would be illegal on the road, and I am sure at least some of your travel will be on road. Very unlikely to matter unless you are unlucky enough to be in an accident (on road) in which case questions might be asked. I'm not even sure if Cycling UK Insurance would cover you. Also, almost all 1000w kits have non-geared motors which have their own issues (I can't remember details, do a search).

A decent legal kit would probably give you plenty of oomf. For example: http://wooshbikes.co.uk/?hubkits SWX02 48V 250W rear hub kit. Their battery is only 12Ah. We have a Woosh XF07 with 13Ah/36v battery on a tandem, and it gives about 35 miles mostly on road, gentle pace, some hills but not huge (Winchester). The 12Ah/48v is about 25% larger capacity. I don't know how much we are gaining by being on road, and how much we are losing by being on a tandem. Woosh have a very good reputation which my experience confirms.

If you haven't already, look and ask at http://www.pedelecs.co.uk/forum/forums/ ... n-kits.42/ You'll get some silly replies but some very knowledgeable ones (including from Woosh).

p.s. The SWX02 48V 250W kit gives a maximum output of 750w. The 250w rating is for sustained output.

hemo
Posts: 284
Joined: 16 Nov 2017, 5:40pm
Location: West Sussex

Re: E bike project advice and help

Postby hemo » 17 Aug 2018, 9:45pm

The off road law is exactly the same only 250w rated bikes are allowed, which means most of the UK. Unless the land is wholly private and you have the landowners permission. Any private land with footpaths and bridleways transiting etc,etc, this includes all parks and national parks, trail centres,basically everything then you can legally only use 250w rated bikes.
The fly by nights that sell these bikes as off road usable are correct they are but don't spell out the exact legalities surrounding their use or more likely don't know the law.
Last edited by hemo on 18 Aug 2018, 10:22am, edited 1 time in total.

hemo
Posts: 284
Joined: 16 Nov 2017, 5:40pm
Location: West Sussex

Re: E bike project advice and help

Postby hemo » 17 Aug 2018, 10:00pm

Battery capacity is better if you know the Wh ( watt hours ) energy of said battery then you can estimate approx. mileage. Generally unless you are a fit roadie /club cyclist expect to use 15 -20 wh per mile.

A 48v 12ah battery will have nominal 576wh.
A 36v 12ah battery will have a nominal 432wh.
For a 36v battery to match the 48v one it would have to be 16ah.

The woosh SWXO2 is a very good bit of kit and will be far better then those 1000w direct drive hubs available, the 1000w sound good because of the bigger numbers invovlved but generally they are sh*te.
They lack low speed power and climbing torque as they are high speed rollers designed for 20+ mph.
They are avergae with 48v but really need 52, 63 or 72v batteries to come alive.
Last edited by hemo on 18 Aug 2018, 9:29am, edited 1 time in total.

olddave
Posts: 12
Joined: 17 Aug 2018, 11:20am

Re: E bike project advice and help

Postby olddave » 17 Aug 2018, 11:27pm

thanks Stodd and Hemo for putting me right on a few things
If I get say a 48v 16ah battery 250w rated motor that would get me closer to target of 40 miles if I needed just to use twist and go
Would the motor stand up to this ? not over heat and burn out

hemo
Posts: 284
Joined: 16 Nov 2017, 5:40pm
Location: West Sussex

Re: E bike project advice and help

Postby hemo » 18 Aug 2018, 10:08am

This goes on a bit so excuse my ramblings :roll: .

Throttle only use will mean the controller and hub being under full power/ max amp draw all the time, at some stage both controller and hub will get warm or even hot. The max wattage these hubs (250w) can handle circa up to 800 or 900 watts is not for continuous use but for spikes in power for when needed esp on inclines or steep ones. Max watts is dependant on the controller max amp rating, I get slightly higher wattage spikes by using 20a rated controllers.

Under these circumstances range of 40 miles will be very doubtful and expect maybe 20/25 miles.
The 15-20wh use per mile I mentioned is for person power using the PAS ( Pedal assist sensor) levels in the lower three assist levels.
A good kit like the Woosh one will have 5 PAS levels, each pas level will deliver an increase in amps giving more torque in each level.
Approx % power supplied and approx. watts would be
PAS 1 13% / 84w
PAS 2 20% / 130w
PAS 3 33% / 215w
PAS 4 50% / 326w
PAS5 100% / 650w

If you were to pedal in pas level 1,2 or 3 then you would get very good range and the 40 miles will be easily achieved, the difference in range by using pas 2 over pas 3 is + 60% range in my experience.
On my bike with tired 3.5 year old battery I get 24 miles approx. in pas 3 by using pas 2 range increases to nearly 40 miles on level terrain at 18/20mph ( I am naughty and have set the cut out speed to 19.5mph) A new battery will easily achieve that and be able to do much more.
My current battery is 14.5ah/36v 522wh so the 12ah/48v 576wh battery will have more stored energy and range.
The advantage of these 250w geared hubs is they have much better low speed torque then the heavy 1000w direct drive hubs, which make the geared hub better to use at low speed and for inclines if a suitable rpm winding speed is selected generally no more then 270rpm. Mostly 250w geared hubs will have a 201 - 270 rpm winding speed which makes them a better choice over the 1000w which are wound to 390 - 490rpm.
The lower the rpm winding the better the torque for hill climbing.
Although not much in it the max speed of geared hubs is approx. as follow;
201rpm 15ph.
230rpm 17mph.
250rpm 18mph.
270rpm 19/20mph.

If a conversion was for a small wheeled bike under 20" then for torque you would need a geared hub with a 328rpm winding to get 16mph, in a larger wheel it would go about 25mph.

A throttle can be quite abrupt on ebikes and mostly should not be compared to moped or motorbike type throttles. Usually ebike throttles are all or nothing some can be feathered a little but they tend not to be very fluid in their use.
The advantage of a pas sensor bike ( magnetic sensing ring type or cadence type ) is that you can if tired or lack leg strength ghost pedal, as long as you rotate the cranks you will be wafted along at 15 mph or whatever the speed is set to, if you want to go faster then you have to increase the cadence to go faster.
Last edited by hemo on 18 Aug 2018, 10:36am, edited 10 times in total.

hemo
Posts: 284
Joined: 16 Nov 2017, 5:40pm
Location: West Sussex

Re: E bike project advice and help

Postby hemo » 18 Aug 2018, 10:14am

olddave wrote:thanks Stodd and Hemo for putting me right on a few things
If I get say a 48v 16ah battery 250w rated motor that would get me closer to target of 40 miles if I needed just to use twist and go
Would the motor stand up to this ? not over heat and burn out


olddave the best thing to do is first go to a ebike retailer and test ride several different bikes to get a feel of how they ride and assist you, all new bikes won't have a throttle but you can get the feel of how the pas works by trying all assist levels whilst ghost peddling.
Although I wouldn't buy from halfords they do offer 1/2hr test rides so use the opportunity to try one or two. I can assure you that a kit like the 48v Woosh kit would be far superior then most bikes you will try and being a kit you have the option of afull throttle for a boost if needed as there is a loop hole in the regs concerning them which isn't covered.

stodd
Posts: 49
Joined: 6 Jun 2018, 10:24am

Re: E bike project advice and help

Postby stodd » 18 Aug 2018, 10:36am

If I get say a 48v 16ah battery 250w rated motor that would get me closer to target of 40 miles if I needed just to use twist and go
I think that the motor would stand up to it, but it would need significant input from you to get the 40 mile range. When I quoted 35 miles on the lesser battery that is using level 2 on the flat and level 3 assist on the hills; out of 5 levels. So, gentle on the battery as well as gentle speeds (?12mph on the flat). We almost never use the throttle; but mostly not pushing too hard and sometimes just pedalling to keep the motor going with no power from us.

As I said before, and I am sure Hemo would agree, ask the opinion of the people at Woosh. They want to sell things that the customers are satisfied with, they aren't just out to get a sale. I've not tried ringing, but they generally answer email or Pedelec forum questions pretty fast.

You would need to guess a bit about the drive, but the Bosch calculator takes into account a lot of details. https://www.bosch-ebike.com/en/service/range-assistant/.
* You can play with the variables to get an idea of what makes the big differences. It came out about right for what we do.
* There are efficiency differences between motors and drive methods but most people say less than 5%.
* Note: all speeds and result distances are in metric.
* I guess riding mode tour would be like our level 2/3 assist.
* The power pack in in wH, so 576 for the 48x12 (as Hemo says); so multiply up a bit from their largest 500.
* Probably the Active Line is the closest equivalent motor.
* You will see very large differences according to surface.

Woosh have got a predictor as well, but much less detailed and I don't think it allows for off-road. Its hill steepness estimates are a bit curious too. http://wooshbikes.co.uk/clearway.php

hemo
Posts: 284
Joined: 16 Nov 2017, 5:40pm
Location: West Sussex

Re: E bike project advice and help

Postby hemo » 18 Aug 2018, 10:49am

Woosh bikes are excellent to deal with and are first class any issues you have they will bend over backwards to help, currently they are an online mail order only unless you live near Southend in which case they have a shop/office on Queens Street and you can pop in to test ride or discuss any options.

If you ringing you will most likely have Hatti the brains/boss answer, most likely she will hand you to over to Tony to speak to who is one of the highly technical guys who know's his stuff as they also build computers etc, so ebike tech is kids play for him.

Regarding Stodd's findings with his conversion they are a bit different to most conversions as the drive has to contend with a heavier bike and two people so more energy will be required from the battery to propel the larger weight mass, conditions ridden in will also have an effect esp strong head winds.
Last edited by hemo on 18 Aug 2018, 10:53am, edited 1 time in total.

stodd
Posts: 49
Joined: 6 Jun 2018, 10:24am

Re: E bike project advice and help

Postby stodd » 18 Aug 2018, 10:51am

you have the option of a full throttle for a boost if needed as there is a loop hole in the regs concerning them which isn't covered.
Are you sure on that. My reading was that a throttle is only allowed on a certified design (I forget the exact terminology) of complete bike, so that nothing put together from kit was technically legal with a throttle that operated above walking speed.

eg:
The e-bike’s pedals must be in motion for motor assistance to be provided
from https://www.cyclinguk.org/cyclists-library/regulations/eapc-regulations

stodd
Posts: 49
Joined: 6 Jun 2018, 10:24am

Re: E bike project advice and help

Postby stodd » 18 Aug 2018, 10:56am

as they also build computers etc, so ebike tech is kids play for him.
I didn't know that. But, I'd say computers are easier to build than ebikes, and there are fewer unknowns and obscurities (though you have helped me understand some of the ebike obscurities, thank you hemo)

hemo
Posts: 284
Joined: 16 Nov 2017, 5:40pm
Location: West Sussex

Re: E bike project advice and help

Postby hemo » 18 Aug 2018, 10:57am

stodd wrote:you have the option of a full throttle for a boost if needed as there is a loop hole in the regs concerning them which isn't covered.
Are you sure on that. My reading was that a throttle is only allowed on a certified design (I forget the exact terminology) of complete bike, so that nothing put together from kit was technically legal with a throttle that operated above walking speed.

eg:
The e-bike’s pedals must be in motion for motor assistance to be provided
from https://www.cyclinguk.org/cyclists-library/regulations/eapc-regulations



If you speak to Tony at Woosh of flecc on pedelecs they make a case for kits not being include in the regs, any bike pre 2016 are exempt as having grandfather rights and this appears to include kits added to bikes.

stodd
Posts: 49
Joined: 6 Jun 2018, 10:24am

Re: E bike project advice and help

Postby stodd » 18 Aug 2018, 11:08am

If you speak to Tony at Woosh of flecc on pedelecs they make a case for kits not being include in the regs, any bike pre 2016 are exempt as having grandfather rights and this appears to include kits added to bikes.
Ah, so that is the loophole, thank you. Time flies: just checked that we had our tandem before that, and in fact we have had this one since 2012.

Still, enough of forums, I must be out on my bike (sadly not the electric tandem as my wife is doing something else this morning).

hemo
Posts: 284
Joined: 16 Nov 2017, 5:40pm
Location: West Sussex

Re: E bike project advice and help

Postby hemo » 18 Aug 2018, 11:08am

stodd wrote:as they also build computers etc, so ebike tech is kids play for him.
I didn't know that. But, I'd say computers are easier to build than ebikes, and there are fewer unknowns and obscurities (though you have helped me understand some of the ebike obscurities, thank you hemo)


The Woosh proprieters/directors i.e, Hatti/Tony Lee like alot of independant importers diversify and have other related business's run in tandem within the same property, as the ebike market can be fickle. However it is a growing market and you will see more kits then bikes becoimg avilable from Woosh bikes as they have noticed their popularity rising and the lack of proper decent kits on the market.

Ebay has to many unsuitable kits available with scant info available on there true capabilties and some have woeful batteries to ideally suit the kits needs.

olddave
Posts: 12
Joined: 17 Aug 2018, 11:20am

Re: E bike project advice and help

Postby olddave » 18 Aug 2018, 3:32pm

WOW there is a lot to take account of when trying to get the right set up
So next week I am off to Halfords and then I will be speaking to Woosh
The water is now a lot clearer thanks to Stodd & Hemo
got say a big thanks to you both for taking the time and having the patience to explain things and now I am on the right cycle path