Very lightweight e-bikes

[Deleted member 4366]

If you look down the page here, you'll see a picture of a shield on the head-stock with a diamond motif. That's the cover plate. I haven't see inside, but I remember seeing a string of single cells a bit smaller than C cells somewhere.
http://www.alibaba.com/product-detail/700c-350w-CE-EN15194-Keyde-battery_970721171.html

 

[Artstu]

If you look down the page here, you'll see a picture of a shield on the head-stock with a diamond motif. That's the cover plate.

I think it's fair to say that we all already know that, you gave the impression that the forks wouldn't have to be removed, but it's now clear that you don't actually know if they do or don't.

 

[Deleted member 4366]

Sorry, I made a mistake. Now that I think about it, you have to drop the forks to take the battery out.

 

[Artstu]

I thought that would be the case, you'd need a very oversize steerer to allow a big enough hole to allow the batteries to pass through.

Cheers

 

[flecc]

The warranty and it's exclusions back up the real concerns about strength that I previously expressed. A one year frame and fork warranty is unacceptably short, and it being shorter than that for the motor and battery shows no faith in the product. The extensive range of exclusions enables them to cop out whatever happens.

Others can believe as they will, I wouldn't risk my neck on them at speed on UK roads.

 

[Kudoscycles]

Flecc,remember that the batteries and motor weigh only about 3-4 kilos,so the bike ,less electrics,could weigh less than 10 kilos....Wiggo and his mates roar down mountainsides at 50 plus mph with a bike weighing only 7 kilos.
So in theory it should be possible to make a safe e-bike weighing less than 12 kilos (road bike) or 14 kilos (MTB bike).
I have a feeling that we will look back on postings like this in 5 years time and find it amusing that we doubted it. However,I am not sure that the technology at this time can reliably offer such light weight.
Am not about to sell my soul on this but I do think we should evaluate such designs because they could be the start of the future.
KudosDave

 

[Kudoscycles]

Wonder why they didn't put the batteries in the seat tube,access would have been much easier.
KudosDave

 

[flecc]

Flecc,remember that the batteries and motor weigh only about 3-4 kilos,so the bike ,less electrics,could weigh less than 10 kilos....Wiggo and his mates roar down mountainsides at 50 plus mph with a bike weighing only 7 kilos.

I know Dave, we've covered this earlier, but as previously said, e-bikes have additional stresses. And those road race bikes you compare with cost fortunes, are made to the most exacting standards, are brand new and rigorously checked before use.

However, what concerns me is that they've given different warranty lengths to various items, showing that they had considered them individually. Their unwillingness to give more than one year for the frame and forks after that consideration shows a serious lack of confidence in those items.

The comprehensive catch-all list of exclusions only adds to my suspicions.

 

[Kudoscycles]

Fleck,I value your concerns. I have also done some homework on the Keyde/Tongxin motors. It appears they both come out of a project of Hangzhou university.
There appears to be a lot of concern about the reliability of these motors.
No big company seems to have used these motors which is concerning.
D8veh,you had a lot of involvement in postings on the endless sphere forum concerning these motors - do you know what ultimately was the outcome of those postings?It's so difficult to ascertain the true picture because so many clearly dodgy postings were made by those with a vested interest.
I have built up good trust with the Bafang products,which rarely fail,it's a shame they don't have a lighter product than the SWX motor (3,3kgs)
KudosDave

 

[patpatbut]

This is a lightweight motor from bafang
http://m.aliexpress.com/item/1298936045.html?tracelog=wwwdetail2mobilesitedetail

Patt

 

[flecc]

I have also done some homework on the Keyde/Tongxin motors. It appears they both come out of a project of Hangzhou university.
There appears to be a lot of concern about the reliability of these motors.
No big company seems to have used these motors which is concerning.

There's been plenty of past experience in this forum with Tongxin motors. Their first appearance was in the US Schwinn Pacific which was an all-round failure, the Tongxin set up for 20 mph assist in a 700c wheel. The first controllers often didn't last long enough for the motors to fail and we eventually saw an email issued by a Schwinn vice president withdrawing the product with the comment that it wasn't ready for consumers. A tiny number reached here, imported by Hilderthorpe Cycles, a small Yorkshire shop.

Used as kits by members, controllers originally also figured prominently in the failures, but a number of motors have suffered broken spindles and slip rings. Some members have gained the skills to repair these and created tools to assist with that.

These motors are most reliable in low stress small wheel applications, usually for lower speeds, a perfect example being the Tony Castles/A-to-B Nano-Brompton with assist to 13/14 mph in a 16" wheel. Mechanical failures have been more prominent in larger wheels, especially 700c.

Schwinn have since used them again in full size wheels with a very low power controller and the Toshiba SCiB low-capacity fast-charge battery, and those appear to be ok in that low stress application.

Cytronex have always used them, but an early enthusiastic band of about four members with those first bikes soon disappeared, so no idea how they lasted. One longer term and experienced member, HarryB, bought a Cytronex to use on his daily London commute and suffered motor failures. Eventually a replacement motor he was given by Cytronex he was very dissatisfied with, insisting it was markedly lower powered than previous versions. He eventually gave up on the Cytronex, swapping to another type of e-bike, but seems to be no longer active in the forum.

A few members who originally argued that they were reliable motors in their larger wheel applications have often been caused to eat their words later. Current members with them mainly seem to have them in small wheel, folder applications.

 

[Deleted member 4366]

D8veh,you had a lot of involvement in postings on the endless sphere forum concerning these motors - do you know what ultimately was the outcome of those postings?It's so difficult to ascertain the true picture because so many clearly dodgy postings were made by those with a vested interest.

Al I can say is that the motors are good when they work. I've ridden two over a relatively short distance including hills, from which I'd consider that their power is OK. The one motor that we had on test broke. Anything that I know after that is based on hearsay. I don't believe that any hard facts came out of the ES discussions. Other than Jerrysimon, I haven't heard of anybody else that's actually tried one - not counting sellers.

The main thing that makes me think that they might be worth considering is that Reef Bikes have been selling them for about a year. If they were bad, they'd have dropped them by now, or they'd be out of business. Surely?

I think that the idea that the frame won't be strong enough is ridiculous. There's nothing that I can see would give it enough additional stress to cause any concern. The basis of the the bike is a a good road-bike like you can buy for about £800 to £1200, which i'd be quite happy converting with a motor more powerful than the Keyde. Who's ever broken a bike by converting it? Incidentally, Reef offer a three year warranty on the frame. I wouldn't take too much notice of the details in the Annad listing. Like many Chinese listings, it's probably just copied from somewhere else without them understanding what it means.

The Keyde rear motor is completely different to a Tongxin.

 

[Kudoscycles]

This is a lightweight motor from bafang
http://m.aliexpress.com/item/1298936045.html?tracelog=wwwdetail2mobilesitedetail

Patt

Patt,thanks for your suggestion but the weight is too high to achieve these very light weights overal-
Bafang,SWX01..........3.3kg (the common one used in most cheap ebike)
Bafang,SYX-EO1.......2.7 kg (your suggestion)
Keyed,100 SWXR36...1.9 kg ( the Keyde rear motor)
The Bafang BPM motor is 4.7 kg,
I am starting to think that it is better to accept the weight of the BPM motor and try to save weight with the frame and batteries....the BH Neo Race Carbon is down to 18 kg with carbon frame,maybe with a smallish battery 15-16 kg is possible.
KudosDave
www.kudoscycles.com

 

[Kudoscycles]

D8veh....do you know whether any battery manufacturer has developed Lithium batteries that are very lightweight,I think we need 8-10 ah about 2 KGs,Lithium Ion seems still to be about 3.5-4.0 KGs.?
KudosDave

 

[flecc]

I am starting to think that it is better to accept the weight of the BPM motor and try to save weight with the frame and batteries....

Cytronex, admittedly with the light Tongxin motor but heavier NiMh batteries achieve the following examples:

Alloy Frame Transeo 1 model = 18.6 kilos

Alloy Frame Charge Grater model = 16 kilos

Carbon Frame Super Six model = 12.7 kilos
.

 

[Deleted member 4366]

It's changing all the time. The latest Panasonic cells are 49g and 2900maH. so a 40 cell battery will be about 2.5kg including case and BMS for 11.6aH with plenty of current for a BPM. Your battery maker should be ale to get them, but make sure that they use genuine ones. There's loads of other cells that can give 20amps each and still more than 2000maH, so you could make a 30 cell battery of 6 to 8 aH for a lighter application.

 

[trex]

amigafan2003 has Panasonic 3400mah NCR18650B's sitting in his fridge. Those are 49g/pc. The strong point of the annad design is stealth. Are there enough customers wanting to pay £500-£700 extra for this? I think possibly but it's a big risk.

 

[bmc]

Hi Guys......First post......but been following for a few months, trying to learn about electric bikes, so thanks to everyone for sharing your knowledge and experience.

My interest stems from having a very steep hill to climb up to my house. I have some hills on my regular loop which I can manage to pedal alright, but it would be nice to have some assist up that last one.

So I only need something small and light, and the Keyde motor and tiny 6.2Ah battery seemed to fit the bill.

That was until I realised the Keyde motor is 135mm wide (OLN), and the rear dropouts on my carbon frame road bike are 130mm.

This is where it is now getting confusing as this thread is discussing fitting this motor to lightweight road bikes, when to my knowledge all road bikes are 130mm dropouts. I'm not counting new models coming out this year which will have 132.5 and 135mm owing to disk brakes.

I hope someone can clarify this for me. I know you can spread steel frames, but I don't fancy trying to spread ally or carbon.

At the moment I'm thinking of sourcing a lightweight cx frame which will have 135mm dropouts.

Bill.

 

[flecc]

I've happily spread alloy rear frames far more than 5 mm Bill. You can either spring them apart that much to get a tight entry or overstretch them at greater risk to make the width increase set permanently. On large wheel bikes the risk to get a 5 mm permanent gain is small.

I've even changed tubes and tyres using frame stretch as shown here on this 26" wheel alloy frame, entailing an over 30 mm stretch:

 

[103Alex1]

I wonder if this one really is sub-12kg and how decent the frame and forks really are :

http://annad.en.alibaba.com/product/1437861210-218567348/11kg_electric_road_carbon_buy_electric_bike.html

What exactly would it really cost to land one here ? Notwithstanding all the concerns, would really like to test ride one as for non-commuting "weekend use" use away from the local 'cols', without spending stupid amounts of money for branding the design itself is appealing (except for the white frame, which I have an peculiar personal aversion to). The Shimano 105 is the minimum gear set I would be happy with also on a bike of that sort. Wonder if it's genuine ?

Must admit it doesn't bother me so much the idea you'd have to mess with the forks to remove the battery, provided that you can charge 'on-bike'. Does anyone know if this is possible ?

I thought long and hard about the pros and cons of "building in" a battery on the Trek project and in the end it has proven to be absolutely fine. I've never had cause to take it out. You might want to for transporting - but not on a 12kg bike !

It would be good to see if the Keyde motors last the course. My only experience of them was hearing one whining with a high pitched resonance at the NEC show last year and seemingly having trouble cutting out !