Anyone done a carbon fibre ebike ?

Hyena

Hyena

10 GW
Joined
Aug 13, 2008
Messages
6,222
Location
Sydney, Australia
People often ask me about frames to convert and when they suggest carbon fibre I usually say no no no but in a case of "do as I say and not as I do", I'm keen to make a super light weight commuter and I don't see why this shouldn't be possible with proper torque arms. I'm not looking to put my usually ~5kw through it, it'll be a small geared Mac or BPM seeing 1500w max. It won't be ridden over anything too rough (I'll resist the urge to gutter jump) so predominantly street ridden.

Cheap carbon mountain bike frames have suprisingly positive reviews so if they survive offroading as normal MTBs I don't see why they shouldn't hold up at modest ebike power level if ridden sensibly.

Anyone with any carbon ebike conversion experience ?
 
It can be done.

What's the point though? A steel frame is 1/2 a kilo more and costs a fraction. Alloy frame is nearly the same weight.

I can understand weight saving in racing. General commuting or trail riding it's not noticeable. Ebiking - pointless.
 
http://www.endless-sphere.com/forums/viewtopic.php?f=1&t=41424

http://www.nzz.ch/lebensart/auto-mobil/ein-fliegengewicht-von-einem-e-bike-1.17318558

e-mountain bike that weighs only 7.66 kg
1.17317736.1341407659.jpg
 
I like the thought and look of carbon as well. Only problem I have with it is you may not have any warning prior to catastrophic failure. Steel bends and aluminum will often crack near a weld sometimes noticeable before failure if you keep an eye out. Carbon fiber from what I have seen just lets go all at once kind of like someone's recent aluminum handlebar. Built well, used within specs and maintained with a watchful eye I think that carbon should be just as good as anything else. I do keep a close eye on my bars and crank as they are made of the stuff. Three years and no problems so far.
 
full-throttle said:
What's the point though?
Click to expand...
"Just because" :lol:
To be honest it's more of a gimmick, for something different and largely because they look cool :p I want to build a low powered commuter to force me to pedal more so I figure while making everything else mini I'd do the same with the frame weight. I've got some trials rims too with big holes in them that in reality are probably no lighter than an expensive brand name normal XC rim or similar but yeah - largely cosmetic.
But the whole thing should be under 20kg which is pretty good. I imagine a light weight aluminium frame is going to be more expensive
than a cheap carbon one ? The carbon ones are just over $300 delivered. I built a bike for a guy recently with an expensive giant (trance xo I think)
and it had no business being as light as it was. I went to wheel it around to the other side of my bench with the same level of force as I would for my ebikes and lifted the thing right off the ground. Bolting a H40 and 1000whr pack on it solved that "problem" :p

adrian_sm said:
http://www.endless-sphere.com/forums/viewtopic.php?f=1&t=41424

http://www.nzz.ch/lebensart/auto-mobil/ein-fliegengewicht-von-einem-e-bike-1.17318558
e-mountain bike that weighs only 7.66 kg
Click to expand...

Yeah I saw that one. I don't need it to be record breaking light weight, as above it's more just to do something different and if I'm going to do a minimal build it may as well look cool too.

Something like this

97.jpg
 
biohazardman said:
I like the thought and look of carbon as well. Only problem I have with it is you may not have any warning prior to catastrophic failure.
Click to expand...
Yeah that's the one thing that's stopped me from buying one already.
If it just cracks on me then no biggy, I say "bah, bloody carbon fibre, I should have known better" but if I'm saying that from a wheel chair after getting busted up at high speed I'll be kicking myself. Or trying to, with my now non-functional legs :lol:
As full throttle says the weight factor really isnt an issue for an ebike, so maybe it's not worth the risk for the gimmick factor...
 
Perhaps use a Chromo fork and put a Tongxin geared hub up front? (I've read that the Tongxin is the quietest of the small geared-hubs like Cute, Bafang, etc) Perhaps an Alfine-11 in the back and a single chainring on the BB?

If you want one of the small geared-hubs, you can help it out a little by giving the motor some gears, with a BB-drive. Shouldn't hurt the carbon-fiber frame at all?

chaindrive1.jpg
 
Hyena said:
I want to build a low powered commuter to force me to pedal more so I figure while making everything else mini I'd do the same with the frame weight.
Click to expand...
Ha ha, I had a similar idea. All made sense until I went for a ride.. :oops: Put it this way - I'd rather commute on a road bike. Ananda Q100 is light but gutless.

Hyena said:
I imagine a light weight aluminium frame is going to be more expensive than a cheap carbon one ? The carbon ones are just over $300 delivered.
Click to expand...
Usually the other way around. The cheap chinese carbon frames are heavy (at least as heavy as alloy) and not to be trusted.

Sub-20kg bike sounds nice. My commuter is 23kg - steel frame, BPM, Headways, front suspension, DH rims. Super-reliable and I spend less than $1k to build it. The donor bike was $400.
 
Under 20kg pulls another positive here in Aus, in that the longer haul trains let you carry bikes when you travel if the weight is less than 20kg... (assuming you can pack it in one of their bike boxes, dimensions yet unknown).
I think I have solved this logistically with a "standard" in that I can take off the hub motor, and put it in a wheel bag and take off battery as well and tote that extra weight as hand-kuggage... mmm... slight side track there... yet to test this in practice...

Hey Hyena... after seeing full-throttle's build adn with a background challenge myself of building a fast light road oriented e bike the bafang style geared motor running around 48 volts 25 amps LOOKS like the bees knees.

Dunno the full specs of his rig, but definately half the motor weight, and compared with a straight 48v at 25A in a dd using one of my kits, the low-end torque was the awesome... hugely noticable.... Light weight, superclean build wit in triangle style Lipo... Very impressive.

Not withstanding ya can often get the geared motors pre-laced in 700c wheels...

I'll race ya.. you go carbonfibre, I'll go old school brazed steel no suspension :) (that's where my geared motor is headed for, single spead rear 53 tooth chainring... an electrified Fixie that's not a Fixie... Oh no! I've gone all Hipster... Someone shoot me...pants tightening, chest and neck naarrowing... tufty beard...noooooooooo)

Joe
 
full-throttle said:
Ha ha, I had a similar idea. All made sense until I went for a ride.. :oops: Put it this way - I'd rather commute on a road bike. Ananda Q100 is light but gutless.
Click to expand...
I wasn't planning to go THAT small :lol:
BPM or MAC - still 1500w odd. That's weak as piss compared to what I normally ride but probably scary powerful compared to the Q100 :lol:

The cheap chinese carbon frames are heavy (at least as heavy as alloy) and not to be trusted.
Click to expand...
I would have thought the same but there seems to be heaps of positive reviews on MTB forums and you'd think people would be quick to rubbish them if they break easily. As I said the whole CF thing was more about the look. Maybe I should invest in some CF vinyl wrap :lol:

My commuter is 23kg - steel frame, BPM, Headways, front suspension, DH rims. Super-reliable and I spend less than $1k to build it. The donor bike was $400.
Click to expand...
Cool, that's not bad. I'd be using an 8ah 18S lipo pack or ideally even 12S with a faster wind motor so the battery weight would be potentially only 2.5kg. The motor is around 4kg, 6 fet controller + throttle and wiring say 1kg so that's only around 7.5kg of added weight for the whole electric driveline. I too would want front suspension over something rigid for the sake of an extra kg or 2. But at the same time it's not worth spending $500 odd on a fox or similar light weight fork. Sounds like I'm looking to come down your current level, but you're looking to go even lower!

winkinatcha said:
Hey Hyena... after seeing full-throttle's build adn with a background challenge myself of building a fast light road oriented e bike the bafang style geared motor running around 48 volts 25 amps LOOKS like the bees knees.
Click to expand...
The BPM is good, the standard bafang you see in most commercial ebikes is rubbish.
Well, not rubbish but a bit gutless in comparison.
The benefit of DDs is they're cheap and you can belt a heap of current into the. Yes geared motors might have more torque for the same low current input but when you belt higher current into a DD that would melt a small motors gears/windings they get up and go.

I'll race ya.. you go carbonfibre, I'll go old school brazed steel no suspension :) (that's where my geared motor is headed for, single spead rear 53 tooth chainring... an electrified Fixie that's not a Fixie...
Click to expand...
Yep, that's along the lines of what I was thinking too. I never shift mine out of top gear although with the lower powered motor I might need some gears for the steep hills. Courtesy of my fairly savage but (thus far!) life saving chemo and radiotherapy I don't have the cardiac or lung function to pedal hard even if I wanted to. I just get dizzy and fall over. haha. But sure, I never turn down a race :p

Oh no! I've gone all Hipster... Someone shoot me...
Click to expand...
haha it's OK mate, we're all ebike hipsters here on the sphere. In a few years time we will all be saying "I was in the ebike underground like 5 years ago man, but they've ruined it now that it's mainstream" :lol:
 
There's carbon fibre, and then there's carbon fibre.

Some manufacturers use carbon fibre as a gimmick - it's not much lighter than alloy, so the advantage is not the weight loss, but the "Ohh, cool" factor. Other manufacturers use carbon fibre because it's the best material, and they're trying to get the most out of their bike.

There is a huge difference between a $500 CF frame, and a $2000 CF frame, but most of that is in the geometry and balance of the bike. If you envision pedaling a fair bit, then I think you'll find that a good quality CF Frame will help you go faster with less energy, but this will be the reason to spend the extra, not a kilo of weight loss.
 
^^ Very true

You could look for a 2nd-hand XC carbon with all the bells and whistles. I'd imagine there will be a lot of folks jumping on the 29er band wagon and getting rid of their 26ers..
 
^^^Mmmm that would be nice, more quality second-hand 26" running gear...
'Kay
***Quick non-carbon fibre related***
For da Build Race, I will be using an old steel "road racing" frame, indeterminate age but judging by the brackets I reckon it's brazed... Even has chrome lower front forks... I found it about 2 years ago, leaning against a tram stop, no tires, busted rusted and last time it was ridden it had been painted firengine red with rattle can house paint...

I rebuilt it enough to ride it round the block, then took all the components off and put them in a box, waiting on time for a restoration. Even has "suicide" head stem mounted gear levers and chrome rams horns (drop bars to you younguns)

I'd guess age would say it is an old 28".. 700c running gear fits it... strengthening the rear and dropouts for torque might be a challlenge... anyways...

the motor I'll use, I recently stripped from a "commercial" build, and pulled apart for my first glimpse into a geared motor... the commercial build was an underpowered "road oriented" 700c based... When I got this the 36v commercial lithium pack was ill, I only ever test rode it on some lipo and it did not give out a lot, I think maybe 200watt compliant so no surprise...Cursory glance at this motor and with my rudimentary knowledge I reckon the motor is good for 500 watts, even possibly 1000.
I need to re-assemble it and am "relying" (read hoping) that by using a single gear on it, I can reduce the "between dropuot" width to squeeeze it into the racer frame.

I am planning on running power through one of my Kit controllers... i've got enough knowledge on these controllers now to drop the max current down to around 10 amps... I have no idea what the top speed of this wheel is based on voltage, but its original form was at 36 volts, so I have at least room to go up to 48v. Be nice if there was a direct correlation with my dd hubs, and a wheel speed around 35kph on 36v... Bout my ideal...

Will be running Lipo or Ping, some kinda mit frame mount for batteries, and trying to be as minimalist as possible.

With current workload (I have a human-powered bike to complete refurbiishing for someone by tomorrow arvo, and a Strictly legal build to complete ASAP, I reckon I could get to proof of concept (powered but not pretty) in about a week..
all the finer faff of stripping down the frame again, rebuilding bearings and components and pretty-fying is gonna take time tho, coupla weeks from that at best, fitting around other stuff... danged if I know...


Or sooner :mrgreen:

*** End non c/f stuff...

joe
 
If you guys are willing to pay for carbon fiber price just for the weight saving, why not go for titanium then? This would make much more sense to me. From what I have seen, it is not like you guys are running full suspension carbon anyways. So the vibration damping vs titanium would be minimal.

I say if you have money for a decent carbon fiber build, might as well go for titanium.
 
I've been wanting to do a frame with just enough steel to make it just strong enough everywhere it counts to make catastrophic failure all but impossible but a frame like spaghetti otherwise. Then use a carbon/aramid weave to provide rigidity and toughness with little weight. Of course it's a gimmick since we have motors, but it's a cool one that makes flowing curves and a battery box as part of the frame itself fairly easy. Mine would be a rocket though, not a legal down under pedal assist...too much competition in the low power arena and too little fun. I can't even ride a 5kw ebike anymore unless it's being used as a truck or a school taxi. :mrgreen:

I can't wait to see what you come up with.

John
 
I seriously love carbon fibre & Ti as a material but I'm not sure they are the greatest of things to stick between your legs.

Old fashioned steel/ali's more forgiving and forewarning....better a creak than a crack.

But an alloy space frame structure with carbon cladding wud be nice 8)

DoD
 
full-throttle said:
You could look for a 2nd-hand XC carbon with all the bells and whistles. I'd imagine there will be a lot of folks jumping on the 29er band wagon and getting rid of their 26ers..
Click to expand...
Yeah actually the majority of frames I found online are 29ers. I was thinking one of those could be actually perfect for fitting a thin, low key battery behind the seat post in the extra space with a 26" wheel but pedal strike would be an issue.
But yeah, I dont want to go buying any whole bikes. Even this one I shouldn't be building! I have so many projects in various stages of completion (or should I say various stages of beginning :lol: ) and I think really it's largely the physical appearance of carbon that's attracting me.

As for Ti, I doubt I'd find one of those cheap enough for what is just another passing project to amuse myself :p And as above it's not really about the weight.

winkinatcha said:
am "relying" (read hoping) that by using a single gear on it, I can reduce the "between dropuot" width to squeeeze it into the racer frame.
Click to expand...
Off topic, but you'd probably need to machine the axle down to get it to fit a narrower dropout. On most motors the wider part of the axle is machined to 135mm width so it fits snug against the dropout. Your GM DD's dont but use a spacer tube instead that the nut on the outside of the dropouts tightens in again. On those ones it's just be a matter of cutting 10mm (or whatever) off the spacer to make it fit, but machining down a little axle on a baby bafang will be almost more effort that it's worth.
 
Dude, it wouldn't be fair if my build was just a straight up bolt on jobby... there'd be no sense of challenge... :mrgreen:

Joe
 
I'm sure the hideously priced blacktrail krautcycle is carbon. Sorry, karbon. https://www.youtube.com/watch?v=NzlLMWAWc9s&feature=youtube_gdata_player
 
Samd said:
blacktrail krautcycle
Click to expand...
:lol: :lol: :lol: I haven't heard anyone use that word in 20 years.
Yeah it's all carbon. And with rigid forks to boot!
I'm sure it's alot sturdier than your average CF bike. Atleast it better bloody be for the price!
 
You must log in or register to reply here.

Similar threads

R
    • Like
Really good article comparing Bafang vs. Tongsheng vs. CYC
Replies
12
Views
10,620
999zip999
999zip999
S
    • Like
Rad Power Bikes: 2016 Rad Wagon Review
Replies
6
Views
5,819
Syonyk
S
Back
Top