Brompton M2L-X (Titanium) - Super Lightweight Pedelec Conversion

[jerrysimon]

Do you know if the controller would fit inside of the main frame tube? Putting it inside probably not a good idea but curious to know nonetheless.

I didn't check to see if it would fit in the frame. Problem would be where in the frame you would put it and getting the wires out ?

As I said my whole project is to keep the "carry weight" of the Brompton as low as possible.

Dimensions shown above. It weighs around 220gms.

Are you sure Sky is a woman? I knew a guy named Sky. It's one of those names that could be male or female.

Would you be able to do estimation on battery consumption for your work/home commute in comparison to the Nano? I'm not sure if you've ever measured how much juice the nano used on average for the commute. Sorta like an estimation without a cycle analyst to figure out the Wh/km. It certainly seems very similar to the Nano in performance based on your review.

Some one else told me Sky was a woman. I will ask her next time I email him/her.

Currently I use between 600-800mAh on my 5.25 mile commute one way pedaling quite a bit myself but remember my commute is pretty flat in Cambridge. A lot is dependent on terrain, weight etc.

This is using my current Nano motor and DIY battery 36v, 2.3Ah 12s1p A123 cells.

Build details here.

Regards

Jerry

 

[jerrysimon]

Ok wet and raining out and I am not interested in watching jubilee celebrations so been playing in the workshop.

The older 2009 Brompton brakes don't really have room for the micro switch which I took out of existing generic ebrake and it would foul the fixing screw shown.

However my new 2011 ones look more promising. Shown here next to the micro switch/cable. The brake fixing for the handle bar is different and leaves room for the micro switch to be fitted.

First cut out the existing hole where the setting grub screw was. You have to open it out to around 12mm and take away some inside material.

More five min epoxy and its sitting in the workshop drying as I type.

Will fit later and report back.

Regards

Jerry

 

[jerrysimon]

Finally I made this smaller switch for my Moulton ebike build to switch the controller off and on using the brake cutout circuit. I will probably do one similar for the Brompton to switch the pedelec on and off as required.

There are lots of handle bar cutout switches available but many of them are quite bulky and large.

Regards

Jerry

 

[polyphasic]

Currently I use between 600-800mAh on my 5.25 mile commute one way pedaling quite a bit myself but remember my commute is pretty flat in Cambridge. A lot is dependent on terrain, weight etc.

This is using my current Nano motor and DIY battery 36v, 2.3Ah 12s1p A123 cells.

holy nettle soup, 15-20 miles per 2.3Ah! Amazing! That's the first post that I've found to provide data on the range for the Nano consistent with electricwheel AtoB claims. Doing happy dance. I'm going to extend the conversation to a separate thread as I don't want to detract from the discussion regarding building a lightweight Goldant Brompton. [h=2]Optimizing range for lightweight electric Bromptons can be found here:[/h]
http://www.pedelecs.co.uk/forum/electric-bicycles/11859-optimizing-range-lightweight-electric-bromptons.html#post142136

 

[jerrysimon]

That higher range really is based on me putting some work in, it being pretty flat and no wind/nasty weather.

More average would be about 10 miles for a 2.3Ah pack. Although these batteries are pretty robust and can take a lot of abuse, its not best to discharge any battery completely if you want it to last a long time.

One of my cells failed after about a year (cheap to replace) and I am now up to about 800 charge cycles and 30 months old. I now always charge at work though half way through the round 10.25 mile daily commute.

Regards

Jerry

 

[jerrysimon]

Ok modified Brompton ebrake fitted and working

View inside showing switch assembly. Requires positioning correctly so that it is closed fully and open when the brake is operated.

Fitted

I am pleased that I have been able to modify the Brompton brake as I detest the stock ebrakes that come with kits.

Well that's just about it now. Switch looks a little untidy but its tiny, works perfectly and is positioned just right.

Been out for a good ride today including finding a nice steep hill (hard in Cambridge). I will post some pics and conclusions of the ride later.

Regards

Jerry

 

[Kenny]

Terrific build Jerry. A classy looking ultra-lightweight electric folder.

All the more impressive that you've built it in your leisure time.

With still no sign of Brompton's own electric bike you put their
development team to shame

 

[jerrysimon]

Thanks Kenny. I plan to send Brompton some details and photos which I have done before and got a nice email back from them.

A couple of out and about pictures from today to finish of the initial review.

The first slight incline I could find in Cambridge lol

More of a challenge this is an actual hill!

This hill is about 1/2 mile long and pretty steep climb, a good test of the motor. The angle of the shot does not make it look steep but trust me it is. Whilst plenty of power to help me up the hill pedaling and not drawing a sweat, it's clear this motor is not quite as powerful as its Nano brother though not much less.

So in summary my opinion of this motor is it is a perfect partner for a light weight bike. Its real benefit is going to be providing light assistance on incline stretches and hills or when fighting a head wind. I see the system as something you switch off and on as required. Although initially, I thought the lack of throttle was going to be disappointing after using the supplied pedelec setup, I can see why they chose this option in preference. As I said earlier the system as it comes with its stock controller is smooth, with nice linear acceleration, good freewheel and whisper quiet after an audible whine as it spins up to full RPM.

Regards

Jerry

 

[shemozzle999]

Hi Jerry,
Will you be taking it for an outing at the Brompton World Championships?
I would like to join you on a circuit around the grounds at Blenheim on the 18th and 19th August and see how it compares with my ageing setup!

Bike Blenheim Palace - Day and Weekend Pass tickets | Register Now | powered by The Active Network

 

[jerrysimon]

Well here is a slight anomaly over the Nano ??

As its wet and I had a few spare moments, I went and fitted a trip computer to my new Goldant bound Brompton. I noticed that it was spinning up to almost 17mph on the stand

When I then tried it on the road this translated to around 16mph or just slightly less assistance when on the flat with gentle pedaling.

I thought maybe I had not entered the wheel dimensions into the computer correctly so I tried the same computer (both are cateye enduro 8s ) on my my Nano bound Brompton. This spun up to almost 16mph on the stand which translates to slightly less than 15mph about 14.7-14.8mph on the flat with gentle pedaling.

Both motors are marked the same i.e. 260RPM, the Nano is also marked 250W and the Goldant 200W and both 36v.

So it looks like the 260RPM Goldant motor provides another 1mph assist on the flat over and above the Nano for the same rim size.

I must admit I had thought it seemed faster when I was test riding it, but had put it down to the lighter Brompton Ti frame. This seems closer to the level of assist, speed wise, I get with a Nano in a 20" wheel as fitted in my Moulton.

Regards

Jerry

 

[shemozzle999]

With the standard green Brompton tyres at a pressure of 80psi I measured my 1 rev rolling distance with me sitting on it at 1435mm which appears to give a fairly accurate readout when compared to a friends bike on a recent trip out.

 

[jerrysimon]

Hi Jerry,
Will you be taking it for an outing at the Brompton World Championships?

I might consider it though had thought it was just a race of Bromptons which does not really appeal to me.

I run the Kojaks at just below 100psi and one rev rolling distance I measure as 1300mm. As I said I used the same computer on both bikes and both bikes have Kojaks on the front so clearly the Goldant motor is running faster.

Regards

Jerry

 

[jerrysimon]

With the standard green Brompton tyres at a pressure of 80psi I measured my 1 rev rolling distance with me sitting on it at 1435mm which appears to give a fairly accurate readout when compared to a friends bike on a recent trip out.

I just went out and measured the "actual" wheel circumference with the bike on the stand using a dressmakers tape measure. The Kojak comes out at 1300mm the same as I measured when rolling it.

I have a Brompton green flash on the back wheel of my M3L at the moment and I did the same thing. That came out at 1340mm ?

Regards

Jerry

 

[shemozzle999]

I have attended the event a couple of years at without competing - I'm far too old for all of that shenanigans.
I treat it as a purely a social day out.
The race start is quite a spectacle it amazes me how serious some of the racers can be.
It provides the opportunity to join in the family run around the course at a leisurely pace and take in the sights of the grounds and have a look in the Brompton tent at all the new developments, they even have a free service mechanic if you want your bike checked over.
Of course this year the E4 group will have a stand so you could try out other Ebikes and the Nano people are usually there as well.
I thought it would be a great opportunity to meet other members from Pedelecs without any formal set up.

p.s. you are right - I got the number wrong should have been 1345 not 1435.

 

[jerrysimon]

Thanks shemozzle999 I may give it a go though its a good 2 & 1/2 hr drive for me.

Regards

Jerry

 

[shemozzle999]

It is a shame we don't have an official Pedelec Member sticker so that other members could be easily identified.

 

[piotrmacheta]

Very impressive. One day when I decide to get a Brompton then I think I'll do the same. Can you tell why you didn't go for the motor with the controller built into it?

 

[jerrysimon]

Very impressive. One day when I decide to get a Brompton then I think I'll do the same. Can you tell why you didn't go for the motor with the controller built into it?

Thanks. They don't do one in the 80mm width, though I guess you could get one and spread the forks wider. Didn't want to do that with £265 Ti forks though!

Regards

Jerry

 

[cwah]

Jerry, I have this brompton brake:

I suppose there is no space to add a microswitch?

Better buy this new brake to add a microswitch?
http://www.sjscycles.co.uk/brompton-brake-lever-30-deg-rh-qbrlev30rh-prod13459/

 

[jerrysimon]

Jerry, I have this brompton brake:
I suppose there is no space to add a microswitch?

Correct. I have those on my 2009 Brompton as as you state there is no room to fit the micro switch. You need the newer versions as you linked to.

As well as drilling out for the switch you have to remove some of the material inside the brake. I used a dremel with a round/cylindrical grinding bit.

Cheaper/free postage here

Also as your motor is on the rear I would use the rear (left) brake to cutout the motor.

Regards

Jerry