Fat Guy Needs a Folding Conversion on Train Commute!

[Deleted member 4366]

After riding the Xiongda, which tops out at 10mph in low gear, i realised that you don't need a big motor to drag heavy-weights up steep hills. Many of us (if not most) only want the motor for the hills. On the flat and down-hill, you don't need a motor as long as you can pedal. OP says that he can't pedal easily, so it's just a question of speed.

 

[trex]

you've got a good battery and good controller on the xiongda and two speed gearbox and a pair of strong legs. The Sparticle on the Brompton has about as much power as the Woosh Gale that I know well, it's no match for the crank driven Zephyr CDN with a Nexus-3 gear box, which is no match for the Big Bear when coming to hauling weight.

 

[RobF]

Bromptons are all but bomb proof, so no problems with the weight of the OP.

It appears he is now considering the expensive option of a new Brommie and kit.

As a Nano owner, I'm bound to throw that into the ring.

I think the motor has enough grunt for the job, and OP may be able to get by with the smaller battery, which would save weight.

A three speed is about right, certainly no need for six.

On the negative side, Brompton with motor and Brommie bag with battery inside is a lot of weight to lug on and off a train.

Doable on an occasional basis, but it's not something I would take on as a commute.

http://www.nanoelectricbikes.co.uk/

 

[tommy2fingers]

ideally need more than 10mph. I have almost zero cartilage in one knee but can gently pedal. when i push too hard, in a matter of mins the knee ache's and is letting me know it's not happy.

i have a new job starting in London in October and its actually given me the motivation to shed some pounds and am joining gym, basically my initial target weight will be 110kg (so a Brompton can be an option).

Assuming a Brompton will be an option, the one i like is 11kg (Zepher is a hefty 21kg). The motor needs to give a min of 15mph but still be able to take on train. the thing I liked about the sparticle is speed, although I think I overlooked the extra cost/weight to achieve the higher advertised speeds. Nano was restricted.

All in all, I'd like a Brompton. I will be no more than 110kg's (honest)!. I need min of 15mph (but pref a tad more). And I'd like total weight no more than 15 ish kg. It will be knocking out 100 miles per week too.

From posts, this appears unrealistic so I might have to consider slower speeds. Thanks for your help & advice.

Thanks
Tommy

 

[RobF]

Whatever you decide, I wouldn't get too hung up on speed.

Bowling along at 15mph will get you there soon enough.

I don't know your route, but in the London area I doubt you will be able to go much faster than 15mph for long enough to make a useful difference to the journey time.

 

[trex]

the Brompton comes in at 11kgs, you need to add the weight of motor, battery, bag, controller, about 6kgs. Also, 100 miles a week without proper suspension is hard.
It's still one of the lightest e-bikes though but you should bear in mind that it will be an expensive mistake if the plan does not work out.

 

[Deleted member 4366]

If you have any mechanical ability at all, it's not difficult to do it yourself on a used Brompton. The risk is much lower then.

 

[trex]

have you seen the price of used Bromptons?
http://www.ebay.co.uk/itm/171426783242
Woosh sold this 6 year old bike a couple of days ago for £470. The guy who traded it in bought a Zephyr CDN. The difference is, he did 200 miles in 6 years and we do 200 miles in a couple of weeks.
You only have to look at cwah's e-Brompton to see how fast the bike gets scratched all over for being used in London.
If the plan doesn't work, are you going to put the old fork back? restore it back to non-electric? or sell the second hand electric bike for half the price?

 

[tommy2fingers]

just for the record really and for future readers of the post.

As trex says, (and many will probably be thinking), its looks like an expensive mistake that could be a chore. My reasons are, parking at Ipswich station £150 p/month plus london travelcard £60 to be squashed into the jubilee line.

I dont have a great paying job in London, so it's a way that I could save cash in long, within 8-9 months if i buy brompton second hand and a new motor.
will make a few calls this week and so it goes full circle will the post result!

 

[trex]

that why I suggested that you pop into woosh in Milton, Cambridge to try their bikes, then pop into The Electric Transport shop in Hope Street where you can test ride their Sparticle before even buying a second hand Brompton.

 

[tommy2fingers]

just a thought, was on another forum where a chap offered to do a conversion for someone...at a cost of course

if i was to buy a brompton off ebay, do any of the knowlegable regulars on here charge to do a conversion for other members? just thinking options at the moment. weight and fold are paramount. not sure if this is good etiquette to ask, apologies if not.

 

[RobF]

Tommy,

I think you are still trying to push water up hill.

There is no such thing as a 'lightweight' conversion.

A Brommie with a motor and controller will weigh about 15kg.

Weight can be saved by a smaller battery, but 20 miles a day means you need 8-10ah, so that's another three or four kilios in a Brommie bag.

In your favour, you will only have to lug this on and off a train - twice - a day, which might not be too bad if access is good.

A few steps or other obstruction on the way will kill the job stone dead.

The only way I can think to save weight is to drive to the station, which will cut the bike journey to 10 miles a day, which in turn allows you to have a smaller and lighter battery.

Doing that answers another concern: 20 miles a day, even if broken up into five mile chunks, is a lot, day in, day out, even on an ebike.

As mentioned earlier, Brommies, good as they are, are not the most comfy of rides.

Having rained on your parade a little, we do have a member skilled in Brompton conversions - jerrysimon.

If anyone can build you a light e-Brommie, he can.

You could try sending him a private message if he doesn't pop up on thread.

 

[tommy2fingers]

thanks for the tip, i'll certainly contact him

actually, i can charge it at work, so only needs 10 miles. (carpark is £150 a pm plus £60 for train tickets at other end, ouch). your right though, and i might only sometimes use it and treat myself to day parking occasionally. also, im led to believe that the eezee wheels make it a doddle to push in/out/around stations...there is hope yet!

 

[Deleted member 4366]

Another thing: A lightweight build gives you better portability, but, inevitably, it'll have low power too, At 120kg, you need a strong motor and battery. The motors in the lightweight ones that Jerry does will melt under that strain. Considering everything, I can't see it working.

 

[derf]

thanks for the tip, i'll certainly contact him

actually, i can charge it at work, so only needs 10 miles. (carpark is £150 a pm plus £60 for train tickets at other end, ouch). your right though, and i might only sometimes use it and treat myself to day parking occasionally. also, im led to believe that the eezee wheels make it a doddle to push in/out/around stations...there is hope yet!

I have rohloff Brompton that weighs 13.2kg (had to weigh it for flying), it's not really the big deal it's made, easywheels go a very long way as you say and the occasional stairs is survivable. the only thingis I weigh around 90kg, I know someone (northernwalker - he has a blog on www) who weighs more like you) - I have abused my Brompton for years without any side effects, he on the other hand has had lots of broken spokes etc..I love my Brompton but thought you need to know Bromptons may have weight limits too

 

[tommy2fingers]

I have body frame of peter jones and strong as an ox, so maybe more weight will be acceptable trade-off for power and still up the odd set of stairs and then onto eezee wheels.

117kg now - on atkins! now targetting 100kg which might help kit options.

regardless of bike, a new job with commute requires a healther fitter me and am quiet motivated. i will get there and hopefully/eventually on an electric brommie!

 

[derf]

I have body frame of peter jones and strong as an ox, so maybe more weight will be acceptable trade-off for power and still up the odd set of stairs and then onto eezee wheels.

117kg now - on atkins! now targetting 100kg which might help kit options.

regardless of bike, a new job with commute requires a healther fitter me and am quiet motivated. i will get there and hopefully/eventually on an electric brommie!

well, two things, I think your motivation/inspiration is great (I'm not quite a peter jones but, when not in a hurry, I often use swinging the Brompton - as one can readily do with one arm - as a kind of workout, weird as that may sound), the second is that I second a Brompton (over the weekend me and OH was on a twenty mile rid, me on the Brompton, and I was saying to her how, over seven years or so the Brompton somehow always end up stepping into the breech as a default ride after other bikes have failed..)

 

[jerrysimon]

I have moved away from the Keyde motors not specifically because they failed, but because they became noisy compared to the Tongxin. I now have a Tongxin (28H with Brompton rim) back in my lightweight M2L-X Ti model.

Even with the Tongxin on board, with the controller and battery in the bag this Brompton is still around 12KG carry weight. With a regular Brompton unless you have a lot of hills to climb I would stick with the two speed which provides good weight saving.

The real challenge is the battery and unless you can build one specifically to match you commuting distance/terrain (assuming its less that 30-40 miles) you will be forced to use a standard 4kg + ebike battery.

Regards

Jerry

 

[Deleted member 4366]

What's your thoughts, Jerry, with a 110kg rider on board at your maximum current of ??

 

[jerrysimon]

Dave,

Its hard to say. There appear to be so many conflicting factors in this case. My Brompton/Tongxin will peak at 12A but rarely reads more than 6A (mostly down at 3 or 4) when I am commuting. My main concern here is just how much pedal effort the OP can put in. The Tongxin motor really is an "assist" only i.e. not thumb and go. Certainly the rider needs to begin pedaling a little before applying throttle. I can easily get my Brompton up to 15mph with minimum effort with the 260RPM version on the flat and maintain 13-14mph on thumb only if I stop pedaling on the flat.

Whilst a higher voltage/current/more powerful motor solution may be appropriate here, the counter problem is going to be carry weight and portability.

I will openly admit all my experience is with Tongxin/Keyde and light weight (non lipo) DIY batteries for folding bike conversions. I will leave others to advise for more powerful but heavier setups.

Regards

Jerry