I am DETERMINED to build a bike that can do this!

Maybe not the first one, but maybe! How cool would it be to be able to ride up the trails at a moderate pace, then turn around and BLAST down them! This guy is truly AMAZING though, I can't believe how fast he is! The thing is, if you watch closely it really looks like smooth riding! Good suspension I guess!

[youtube]cVarDBb199M[/youtube]

Top of the line stuff, and talent. Fox shocks are some of the best. Great video. I wish I had trails like that where I live. Keep your setup as light as possible.

That's what I was thinking. I am fairly sure I can get it under 50 so it should be decent. I have heard that the upper class downhill bikes are actually heavier than the cross country stuff, like mid 30lbs range, so if I can get it around 45, I really am not too far off.. I am looking into as many carbon parts as I can afford to keep it light! My first rendition may or may not be on target, but I will get there for sure! I think I can get the frame and swing arm around 6-7lbs, add the motor (about 9) batteries (about 9) wheels (4-5ish) and crank (about 1 for a good one) and I should not be too far off as long as I keep the little stuff light like 150gram Carbon handlebars, 160gram Handlebar stem, only have one shifter for the rear derailleur, Single front sprocket, stuff like that and I should be able to get there...

Well don't be no weight-weenie sacrificing strength for weight. Just start with a quality downhill bike. If you try cutting the weight too much.... like an XC bike loaded with 20lbs of electrics.... that's not going to work very well downhill.


That video reminds me I need to get back into mtn biking. NO CARS. Ahhhhhh those are some sweet trails. And that's what a quality mtn bike performs like. (of course ridden by a pro)

I'd say any hub motor is out (weight position among other reasons) ...

get a good downhill bike. say sana cruz bullet. r/c motor. lipo. r/c controller. solar charge station at top of mountain.

most real DH bikes are prettly heavy already. but also have great suspension. which IS the key to going downhill. eg FOX 40 Marzocchi 888 on front. 8 inches travel .

I will be doing this soon!!! my frame is a RM9, should be perfect for this application.

ROCK AND ROLL !!!!!!

and when is matts going to do a crazy DUH bike (down /up/hill)!!!

Yeah, but I am going to try the MAC modified for the purpose. Its only 8 lbs and I doubt you would feel it that much to be honest... We will see..

You will feel it. and the thing will fry the first time you try climbing stuff like that.

But it might work to have an RC motor with blower cooling, and drive the chain through the lowest possible gear. Then start stashing the lipo at the top, so you can ride down with nothing but a tiny bit of motor and chain weight. The last ride down, you load a knapsack with lipo you've been stashing up there.

I know how you feel, too bad there isn't a ski lift everywhere. I'm liking my compromise though, a good slow winding rear 9c. Allows me to ride up and down fairly steep stuff at 10-20 mph. But with all that weight, I'm not jumping stuff. I got the hucking stuff out of my system on snow when I was younger. bottomless powder beats stumps and rocks for a landing anyday.

Well, the thing is, I can ride that kind of stuff on a 125cc MX bike NO PROBLEM and its WAAY heavier than my bike will be, I really doubt the weight will be a concern. Possibly to a TOP professional rider, he would be able to be bothered by it, but I really doubt it would hinder any average riders performance. And as for the burning up issue, if I can get the gearbox portion to live, the motor will take the 1800-2000 watts I will be driving it with I think, as its been tested that far on here a few times from different people, they just had trouble with the gears. I am hopeful I can make it live, but if I need to go R/C then I will do it. I just want to try the Hub due to the ease of manufacture, I don't expect it to race up the hill either, just make it easier so you don't have to walk the bike up the hill....I think that would be enough... Cooling of the motor will likely have to be addressed but I have a few ideas for that too...

It's nice to dream.... :lol:

but seriously tho.. i don't see it.. even IF you could build a bullet proof motor/gearbox setup ( a huge challenge in itself ) the bulk you have to add in battery packs would make it a real pain to roll with. Hard hits ( and the inevitable falls/crashes ) means you have to protect everything, snag a wire, poke a lipo cell, and it all goes wrong really fast..

Trail riding, yes... serious DH , no. :|

Well, I will at least give it a go, and if I miss the mark by a little, then I am left with a KILLER trail machine, so hey I think that would still be a win!

Agreed. (with Ypedal)
If one tried to go on downhill tracks at a speed like that with ebike motor components and batteries strapped to it....
It'd end ugly for sure.

On an aside. Sometimes I don't feel any different to when I was 20 years old, but when I watch a video like that one I realize
that , at 46, I would have to go a whole lot slower, to avoid a painful stack ! (and humbling lesson about healing)

Whiplash said:

Maybe not the first one, but maybe! How cool would it be to be able to ride up the trails at a moderate pace, then turn around and BLAST down them! This guy is truly AMAZING though, I can't believe how fast he is! The thing is, if you watch closely it really looks like smooth riding! Good suspension I guess!

Click to expand...

Its a shame you are so far way , you build the frame and let me sort out the power plant yes it can be done with a rc setup ,I am working on it I am at the stage that I really need a decent custom frame but I am really struggling with my confidence in my ( lack of ) welding skills

edit:
Look at the cross over between cycle components and light weight off road motorcycles i.e trials bikes, look at the frame design of a trials bike ( they are very strong and very light ) a rolling chassis of a modern trials bike is only around 30kg and a lot of this weight is the wheels and tyres...

Still working on this Karpiel Disco, but the X5 on the rear doesn't really seem to upset the handling as bad as I thought it would. The bike weighed in at 30 lbs stock, (light for a DH bike) add 24 for the X5 and it already weighs 54 lbs. Another 15 or so for controller and Lipo, brings it to ~70 lbs give or take. Realistically, it will never be as 'flickable' as it was, but at 48, I don't heal as fast as I used to either.

I do intent to sell this frame as a bare frame and anyone can do their own custom bits to it, I figure, that doing that will just add to my sales...I also plan on a "you assemble it" style kit too, for the guys trying to save the assembly costs. I truly think this can be done, and I will do my best to get there!

-Bryan

You don't need a motor when you're going downhill anyway :lol:

We just want you to do it. And when you need to re-engineer and adapt, after trying, is where we can all learn. Innovation is what comes from ideas like yours. Desire can, many times, overcome what seems impossible.

No need to have something super light weight for fun , better build it strong to last and save your money for other fun stuff. Think Hub motors are out , and btw half the speed this guy is going is also fine....
Video is awesome , he's got skills !

One word of caution though : Please , PLEASE don't go so fast yourself on trails with trees around them......

Trees are like nature's own concrete post's , the will NOT give way. Body armor and helmets will help but you can still break your neck , your back , crush internal organs or will still simply kill you because of the deceleration forces on your body.
Just think of how many snow ski people are killed each year because they hit trees.
Don't ask me why I know (not MTB related) ....both my tightly laced sports-shoes were lying 9 feet away almost perfectly next to each other like I put them there myself (I will never forget that one in a million chance freaking sight)
When you are in the hospital you are just a miserable sack of bones and organs , your whole world becomes veeeerrryyy tiny even the most boring thing in the world looks like heaven to you then.

Trees in the forest are nice , but don't hit them.

edit : I just re-read my post and I sound like some old preacher telling youngsters what not to do.
F.it , go nuts...have fun but keep you're brain working at the same moment. Probably just bad memories.....I guess I just related to some of the other persons who said they weren't that young anymore and needed more time to heal ( I am not even 40 myself) For heaven's sake I hope I will not turn into a "grumpy old man" later in life...... Blissfull shortsightedness and bravoury where did you go ? The ones who dare and get lucky have a great life for sure.

Evoforce said:

We just want you to do it. And when you need to re-engineer and adapt, after trying, is where we can all learn. Innovation is what comes from ideas like yours. Desire can, many times, overcome what seems impossible.

Click to expand...

That's exactly why I want to do it! Not to mention to be the first! But even though I know the HUB will have a hard time with this, I think the learning experience and tech from the buildup of it will make a hell of a cool Urban assault vehicle! I am sure it can and will do that much! I have big plans on the horizon for an R/C type setup for the real build, but I need to get something built so I can at least have something to offer to the public. Hopefully I can sell one or two to finance the design/construction of the all out "HIGH CURRENT" R/C bike! This is at least my plan, but plans change as we all know, and I could have a little something cool in the near future with a fellow member if all goes well...

Fligh High said:

No need to have something super light weight for fun , better build it strong to last and save your money for other fun stuff. Think Hub motors are out , and btw half the speed this guy is going is also fine....

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Don't worry quality AMERICAN 4130 Chromoly is one of the strongest/lightest things you can build a frame out of (if its designed well), and it does not work harden and crack like Aluminum (ALL Aluminum by the way), and crack and splinter upon a little Impact like Carbon Fiber, it just takes it like a champ and gets battle scars!

Evoforce said:

We just want you to do it. And when you need to re-engineer and adapt, after trying, is where we can all learn. Innovation is what comes from ideas like yours. Desire can, many times, overcome what seems impossible.

Click to expand...

This is of course true.

I didn't mean to put a negative spin on your idea Whiplash, just trying for a little balance.
I tend to fully agree with your opinion on chromoly also.

Go for it !

Ypedal said:

It's nice to dream.... :lol:

Trail riding, yes... serious DH , no. :|

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Hey Ypedal.. I would say:

Trail riding, yes... serious UH , YES. :wink: [/quote]

Up hill

Doc

LOL, DOC glad to have you! UH bikes rule!

Not easy but very doable

using a dh bike frame = FAIL
any bicycle frame? = FAIL
for they are not designed to handle the metal stress, torque, g-force, etc... for this type of riding.

what to use is a custom frame built as a dirt bike like this one -
http://www.motopeds.com



and use the right motor for it.

^^Deec will have a "Crisis" in his pants when he sees that pic mate hahaaa... Full agreeance with GWhy & Doc...well built rc setup will do that...uphill

KiM