10kw Carbon build possible????

[oldskoolhead]

carbon is not stiff it is flexible hence why a carbon frame feels smoother to ride as it absorbs some of the shock

Seriously? You have to talk a bit more in depth to make sense of the materials. All C. fiber fabric is not alike. Some is much stiffer/ stronger than others. Fiber to resin ratio? Resin types? Fiber orientation / direction/ weave? Vibration dampening should not be confused with stiffness. Even very stiff materials when made in extremely thin sections will flex significantly. Too many factors to be so general regarding off road carbon frames which are typically very over built.

yes you are correct carbon can be made more stiff laying it omnidirectional but resin to cloth ratio will always be the same if a resin infusion process is used as it is drawn in under 100% vacuum or for a part like a frame i imagine a pre preg carbon would be used which again is going to be the optimal amount of resin, i did say im not saying it cant be done but a bicycle frame is just that, it is not designed to carry the extra weight and travel at the extra speed that a 10kw ebike would require this is motorcycle territory you only have to go on youtube and look at all the repair videos there are with carbon cycle frames and these are being used as designed for pedal power.
you have to remember on a 10kw ebike you are going to be traveling at high speed and there is no warning when a carbon frame is going to break it just snaps and you face plant, even an over engineered off road bicycle frame is only over engineered for that use, it is assumed that you will be pedaling and not carrying heavy motors and batteries and traveling at motorway speeds lol
alls im saying is for a 10kw bike i would look at motorcycle carbon frames i wouldnt even consider using the frame in the opening post with anything more than 500-1000w or over 30mph if you value your life, after all 10kw is motorcycle power, its the top end of learner legal, its like 125-250cc type of power and they generally dont use carbon for motorbike frames because it is pointless and safer to use metal, a few grams off a 10kw bike is neither here nor there then compare what you are risking if it breaks hence why they are not that common even in formula one, carbon is used on bicycle frames because under pedal power a few grams does make a difference and the risks arnt as great if it does break, it is a great material but there is a reason it is generally not used structurally on motor vehicles.

 

[Chalo]

dont give a ***** of people they dont have any experience of anything.
carbon is the best material you can get/build when theres stiffness needed.

you can do everything with it....except last over 10 years and wreck some gaps in it

I've built spacecraft structures with CFRP. My practical experience with it is one of the reasons I'm hesitant to use it in a bicycle. You?

I've also witnessed many unnecessary failures of bicycle parts in my years of working as a cycle mechanic that came down to CFRP being used where a metal would have been a better material for the job. For example, I watched a coworker test ride a mountain bike down the four front steps of the shop, and saw its carbon fiber handlebar snap off before my eyes. Despite the fact that I have seen hundreds of times as many metal handlebars as carbon, I have never seen a metal handlebar snap off firsthand.

I know that CFRP is a good material for some things, but not nearly as many things as it is used for. Almost everywhere it's used in place of a metal, it makes for a machine that is less fault tolerant than the metal equivalent. When you start discussing putting more than 13HP of motor power through a bicycle, fault tolerance is one of the most valuable qualities to maintain.

 

[Doctorbass]

I can say that i have absolutly no worrie about strenght of the NYX bike carbon frames !

These was tested in every possible way for endurance test ( see link below as exemple)and high impact test to try breaking them. The guys that tested it with their specialized bicycle test equipment was really impressed to discover that the frame exceeded the limit some of their test bench without breaking! They all agreed to say that this frame is way too strong !

And guess what.. ? after over 7 years of many ebike i have tried i have never tested any bike frame that was as stiff as this one and that make you feel in perfect confidence like this one! It is truly AMAZING!! :wink:

It is so tough that after a guy that tried it jumped 8 foot with it my Manitou six way fully compressed and got stock in compressed position from a full stroke ( it was adjusted too smooth for that jump) so the rear shock broke with a 450lb spring... the frame took the rest of the impact without any dammage!. Believe me... normally a DH bike frame would have bent with such impact!

at 2:03
http://www.devinci.com/dtv/video_53

at 0:44
http://www.devinci.com/dtv/video_80

and many otehr test for the head tube stress with dummy fork etc

Doc

 

[amberwolf]

Despite the fact that I have seen hundreds of times as many metal handlebars as carbon, I have never seen a metal handlebar snap off firsthand.

I've had a metal stem (on DayGlo Avenger's base bike, 2005 Columbia something-or-other) long before I got into motors) snap while I was riding normally on a sidewalk. I'm guessing it was a defective weld, because IIRC that's where it snapped.

I've long since lost the files for the digital pics I took of it (maybe they're on a DAT backup somewhere), but it looked innocent enough. Except for the almost-broken point of my right shoulder I landed on, and my head and neck that also hurt for a good while.

But that's the only non-overloaded or overstressed or maladjusted metal part I've managed to break in my life of bicycling. :lol:

 

[cheekybloke]

Despite the fact that I have seen hundreds of times as many metal handlebars as carbon, I have never seen a metal handlebar snap off firsthand.

I've had a metal stem (on DayGlo Avenger's base bike, 2005 Columbia something-or-other) long before I got into motors) snap while I was riding normally on a sidewalk. I'm guessing it was a defective weld, because IIRC that's where it snapped.

I've long since lost the files for the digital pics I took of it (maybe they're on a DAT backup somewhere), but it looked innocent enough. Except for the almost-broken point of my right shoulder I landed on, and my head and neck that also hurt for a good while.

But that's the only non-overloaded or overstressed or maladjusted metal part I've managed to break in my life of bicycling. :lol:

I have had metal handle bars snap off at the stem when jumping off a whole 4 steps on a non e bike more than once.
Maybe the stem was too tight but it sheared off in one movement and i stayed on the bike .
Darren

 

[speedmd]

even an over engineered off road bicycle frame is only over engineered for that use

So a carbon mtb bike that can safely bomb a 50mph downhill flying through the air much of the time with a host of rider sizes /weights, can not handle 40mph on the road with a hub motor and a well placed battery? The wool shorts crowd is out in force on this one. It has nothing to do with construction material and everything to do with how its implemented. 10kw of smooth power into well designed torque arms and dropouts will be no issue with this. Wheel base will be at speed.

 

[richdeloup]

10kw of smooth power into well designed torque arms and dropouts will be no issue with this

Not sure about well designed ??? This is my first mock up out of aly, the arm goes approx 50mm up the frame and is held in place by polyurethane for now. Once tested and refined, it will hopefully be steel and cast in place with resin then wrapped.... Like you say, testing for wheel base/height etc, may go back another inch?
Wool shorts crowd, that's a good one

 

[richdeloup]

Surely there's nothing structural about this bit?? Thinking it may be a good place for series disconnect plug/charging port?

 

[speedmd]

If your road / gravel road riding at speed, you may want to add 3 plus inches to the wheel base. Many of the guys here can attest to the bennies of the added length. For tight trail riding, you may be good with just a inch or two. Your shock will need much higher dampening /spring power and the frame beefed up significantly in the pivot mount areas. Add like Doc did with his big carbon skin panels, it would serve to mount and house battery sections and stiffen those areas at the same time.

 

[richdeloup]

frame beefed up significantly in the pivot mount areas

I was just looking at this now opened up. It will be solid once cables are in.

 

[richdeloup]

Here's my attempt at drilling out an axle a few days ago. 6mm exit wound, yes 8) , is there an injury and scars thread on here?

 

[dachopper]

I'm currently prototyping a production carbon bike..... The best thing about carbon is that it is easy to use and make custom shapes / thickness etc, it's significantly lighter and stronger than steel, and much easier to manufacture yourself.
Don't underestimate the weight saving..... they are huge !


I would never however start with a bike and use "it" as a base model and just add 10KW worth of stuff to it. Given that I hit 89Kph on my 3KW motor..... with 10KW you need to increase your safety and impact factors, wheel strength, shock strength, brake cooling, because of the speed your travelling at.

 

[speedmd]

You will want to get friendly with the mat type material to help fill!

 

[richdeloup]

Given that I hit 89Kph on my 3KW motor..... with 10KW you need to increase your safety and impact factors, wheel strength, shock strength, brake cooling, because of the speed your travelling at

I just really want to be able to do wheel spins in front of girls, however will be looking at all the aspects above to some degree.

 

[gogo]

It is so tough that after a guy that tried it jumped 8 foot with it my Manitou six way fully compressed and got stock in compressed position from a full stroke ( it was adjusted too smooth for that jump) so the rear shock broke with a 450lb spring... the frame took the rest of the impact without any dammage!. Believe me... normally a DH bike frame would have bent with such impact!

I'm reminded of a Judge Wapner episode where some lady backed into a motorcycle and knocked it over by colliding with the helmet hanging on the side of the bike. Judge Wapner declined to replace the helmet because 'it looked ok to him', even after the motorcyclist explained that fiberglass helmets were designed to absorb impacts by sacrificing their internal structure, and were expected to be replaced after impact. Wapner thought he was bull-chipping to get a new helmet.

Has the factory ever tested a frame after such an impact? Do they recommend that you keep riding it? Have their frames been independently tested according to some standard? Do they disclose their testing standards beyond the description of "bench test"?

I'm not trying to be a smart-ass, I'm just wary of unqualified claims from entities that are trying to part me from my money. I also understand the general mentality of consumers belied by the quote from the video, "When buying a new bicycle, most mountain-bikers pay very close attention to the quality of the paint job."

 

[richdeloup]

You will want to get friendly with the mat type material to help fill!

arr yes, that's exactly the sort of stuff I was thinking of, thanks

 

[richdeloup]

If I go down the hub motor route, i have a question which may have been covered before?
Rather than drilling out one side of the axle to take 10/12g, has anyone drilled out both sides to a lesser degree? I'm thinking that if I want sensors, thick phase wires, a temperature cut off thermistor/switch and a monitoring thermistor then wouldn't drilling a 6mm hole the other side be better than opening up the existing one further?

 

[richdeloup]

@boisrondevens

If I go down the mid drive route I'd be interested to learn more about your RV120 set up, with or without sensors, controller etc? Do you have a thread on this build?

 

[amberwolf]

If you click on the Profile button in his post, or on his membername, the build thread is his most-posted-to thread there.

 

[richdeloup]

If you click on the Profile button in his post, or on his membername, the build thread is his most-posted-to thread there.

Aharrr, thanks

 

[richdeloup]

OK decision made I think, going to take boisrondevens advice and dive into my first mid drive attempt. I'm figuring that I should have the room if I move the dropouts back a bit more and the more central weight distribution would prob do me some favors?

 

[speedmd]

You will have suspension that works better also without significant mods. If you still want 10kw..... http://www.plettenberg-motoren.net/index.php/en/motor-serias-nova/motor-serias-nova-15 I am saving up for one.

 

[boisrondevens]

http://endless-sphere.com/forums/viewtopic.php?f=28&t=64342

 

[flathill]

Carbon in a wonder material. The problem lies with the material you impregnate it with. 99.8987651321% of the time it is fine but QC control needs to be really strict for the matrix material (epoxy or whatever). The other issue is how does the matrix age?

Even with a bad batch of steel or a aluminum frame that had a bad heat treatment, the material will still retain most of its strength, and even if it does fail...the fail mode is much more benign. Aluminum with fatigue over time but steel rusts. Metal matrix or amorphous metal for the win.

 

[amberwolf]

Just thought I'd link this thread here for reference:
Calculation of front fork stress due to hub motor