Mid drive DIY frames?

Ham

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Feb 18, 2016
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Afternoon All,

I am about to embark upon my next build and would love some input from you fine folk.

The cyc x1 pro gen 2 looks like the front runner right now as I am a mid drive guy at heart due to my motor bike years and offroad use.

I am trying to put together as many frame options as possible and Futr beta is pretty much perfect ish for my taste and battery size requirements, however, the price for a new one is prohibitive at this stage.

I am torn between a good downhill mtb frame like a giant downhill and use one of those velcro type frame bags for the battery, which isn't ideal visually for me tbh but would make motor mounting simpler and the whole project cheaper and a nice box style ebike frame...

If anyone has any ideas on DIY frame kits for mid drive then I'd be appreciative!

I did find an old thread on this subject but it has no images left and lots of dead links....
 
How fast you want to go? How far? On what terrain? Do you want to jump?
 
How fast: about 30-40 mph max

Terrain: mix of road and downhill so some kind of all mountain/enduro frame

Jumps: yes but nothing big...a few feet at most

Range: 30+ miles at a mix of PAS and occasional throttle
 
For those specs any mid drive conversion would do, no need for a custom frame for it. Get a frame with a steep downtube so you can mount the motor and battery under it.

The whole project would be much cheaper if you get the donor bike used. People are selling top notch bikes with little use for 50-70% off all the time on pinkbike.
 
There are a few good all mountain bike frames that would be good donors. I've got a cyclone on a devinici and ride it hard and it does well. Cyc would be even nicer.

https://ibb.co/sHSCXq3
 
Thanks for the input guys, appreciate it.

My only real issue with converting bike frames ( other than it doesn't look as slick) is the battery mounting... finding a good hard shell case is a challenge... any ideas?
 
You can buy the 3 dolphin case sizes empty, and fill them with your own battery.

I like frame bags, but not the triangle bags for they don’t fit on DH frames. I use top and down tube bags from Willier, small saddle bags from China, seat post bags and front bags (fork mount) from Axiom. Together, they can adapt to any DH frame, for batteries, tools, connections... And they keep the bicycle look to the bikes, much better than blocking the triangle. I build with modular batteries, 3 bags about 750Ah each RC lipo: One front that is always on, one top tube, one down tube, that are sometimes removed, swapped to another bike, assembled in different voltage series.,. Very flexible and practical system, that share common mounts on all my bikes.
 
Ham said:
Thanks for the input guys, appreciate it.

My only real issue with converting bike frames ( other than it doesn't look as slick) is the battery mounting... finding a good hard shell case is a challenge... any ideas?


If 30mi while doing PAS is enough, consider something like this.
https://www.electroncycles.co.uk/product/72v-12ah-864watts-jumbo-down-tube-battery-sony-vtc6-cells-60amps/

Will max out cyc 72v controller at 4kw. 40mph+ easy.
 
Ham said:
I am trying to put together as many frame options as possible and Futr beta is pretty much perfect ish for my taste and battery size requirements, however, the price for a new one is prohibitive at this stage.

The Beta is a bit of money but you need to make sure you are being realistic about used mountain bikes and their costs. There are few Downhill bikes with adequate space for easy battery mounting. If you find a killer deal on your favorite used MTB frame you are still going to need hundreds of dollars of bearings, pivots, headsets, shocks and forks. If you are going to be hard on it and jump then you are going to want it to be durable. Battery boxes and mounts that will survive a crash can be pretty tricky.

Having built a handful of ebikes out of regular bikes I'm starting to look pretty longingly at ebike specific frames. Everything I touch ends up looking like a science project. However I have not been able to talk myself into a FUTR yet either. I keep taking the bait on used money pit mountain bikes.

One upside of a non ebike mountainbike frame in my opinion is that the companies designing them have tons of experience in engineering bikes compared to a lot of the ebike specific frames. I am not trying to knock FUTR as I have never ridden one or even seen one in person. My gut feeling is that world championship winning mountainbike companies have the engineering figured out compared to ebike companies who's main priority is making a hollow box of a frame for batteries. Maybe the MTB industry design gimmicks have me fooled. Maybe the suspensions are designed primarily to eliminate pedal bob that doesn't matter with a motor. IDK. Just thinking out loud.

If you have some fab skills you could buy used high end mountain bike and just make a front triangle to hold your batteries that uses the same mounting points for the rear triangle and suspension. That is no small task but in my opinion is the best of both worlds unless you have some major bike engineering skills. It leaves the engineering intact and still gives you a nice enclosure for batteries.

I don't want to discourage you from DIY since that's what we do here. Just make sure you are making the best decision based on whether you enjoy the ride or the build more.
 
I didn't know about the dolphin surrounds being a separate item you could buy...thank you!

I have spoken with Electron cycles, very helpful chap once you can get hold of him.

Frames, I have previously built a mid drive on a stumpjumper fsr frame with lipo back pack style batteries (still have the mtb sans motor and still a possible option if nothing else plans out) and fabbed a RC high power one into a stealth clone frame filled with 40ah of 18650s...which was a total hoot but this time around I would like a little lighter and after spending time on a levo I really feel that 1500w is about the max I want for this build....those bafang g510 motors look almost perfect!

Currently looking through Alibaba for frame options to go with one of those g510 motors...I just need to workout the battery set up in those frames. I have a very skilled friend that manages the battery side of things for me for the most part.

I am happy to do a little fabrication as I have some steel welding experience with a gasless hobby MIG and would ideally love to get into TIG aluminium welding but those AC DC HF Tigs are as much as the build itself:)

Thanks again chaps for the help
 
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