Here is my frame and mxus motor

Here is the cross country bike I bought. Its a Specialized Rockhopper XC FSR
https://www.flickr.com/photos/128734122@N04/15583487553/
Is there a way I can make the back suspension part wider. This one measures just under 135mm, I was thinking I would kind of like a fatter tire with a longer rear end. Make it out of steel instead of the aluminum, make the rear to measure 145mm wide. Would put everything out of wack, the rear derailleur line to the crank.


Here is the MXUS 3000W V2 motor I bought
https://www.flickr.com/photos/128734122@N04/16015968490/in/photostream/
You can see the slight minor damage

18fet Lyen Controller - $200
25A 14v DC Power Supply for Chargers (350W) - $39
HobbyKing™ ECO6-10 200W 10A 6S Bal/Dis/Cyc Charger w/ acc. - $40
I have a line on some Turnigy 5000mAh, 4s1p 20C - was thinking 75V

If the swing arm is steel, there's no problem making it wider. If it's aluminum, it would be risky to widen it more than 5mm imo.

Hmm...

yeah, that swingarm + motor = not a great match IMO. 5mm isn't too bad to spread Aluminum rear forks but +10mm is pushing things and good luck if/when you must R&R the wheel. It's hard enough spreading dropouts 5mm with a pry bar or large screwdriver when re-installing motor/wheel. Nice light frame like that I'd probably go with a Mac motor.

75V from 4S bricks, 20S I suppose? I use the same bricks @ 16S = 67V HOC (hot off charger) or 59V nominal. I'm fond of 16S size/shape format and using 8S CellLogs for quick checks of cell conditions. Plus, can run 3077 FET controller (Ask Edward) which is slightly more efficient than 41xx higher voltage rated FETs.

Here's my 16S1P pack from 4S hardcase bricks:

You are kind of screwed with that bike anyway, you are missing not just the shock, but a crucial rocker arm part of the rear suspension. It could be possible to fabricate it, but finding that rocker for sale will be tricky. Look up pictures of your year bike to see what that rocker looked like. Mine is a different year, so tracing my rocker arm won't work.

Re making a steel replacement for the swingarm, it can be done. Look for the Farfle swing arm threads. He was selling one to fit a Genesis frame at one point.

No doubt about it, you got a project on your hands. I'd start with getting the bike rolling, then for now, grab a cheap 135 mm motor. Then work out how to build, or get built an adapter to make that bike 145 mm. Much wider a tire, and you won't clear the front gears with the frame. Most have gone to a smaller diameter rear tire, so a fattie can fit in the stock frame width. Farfle's swingarm also made the bike a few inches longer, allowing a fatter tire to cram in.

5 mm wider on one side won't screw up the chain line that much.

Lots of builds like this, big motor with a moped tire and rim. Again, for now just get the bike rolling with a cheap 135 mm motor. You want to ride this summer, not next summer.

I widened this one to 150mm for my Xiongda motor. I put two pieces of wood in (planks) and then smashed a wedge between them with a lump hammer. I can't remember how far I had to spread them to spring back to 150mm. I think it was about 200mm. I've stretched a few aluminium frames and never had a problem.

The entire bike is aluminum, I think that bike is toast but atleast I got a crank and f.d. out of it, my current one is something like 44/32/22, so its just a touch off on the 44 gear, should be 42. I could easily swap everything over no problem from my current bike over to that, but its that rear suspension piece thats tough to acquire cheaply (under $75), that frame only cost me $20, should have just stepped over it.

It never even crossed my mind that a smaller rim, with a wider tire would totally fit. I am going like 19" moped rim, just wanted a fatter tire is all, plus a steel rear for strength. I measured it, 3.5" wide tire fits at 10" in from where the wheel peg sits. My motor might just be too much power for that rear suspension.

The batteries I got lined up are like $25 4s1p hardcase, puts it close to 14.8V at 5000mAh. Wouldnt 5 of those be good, to make it like 75V 5000mAh?

I should be on the hunt for a 100% steel frame, with disc brakes. I got to hit that community bike shop now every day with my magnet.

Dudes. here's what you need to spread dropouts. Powerful, precise, gentle. As close as your nearest trunk.

markz said:

The entire bike is aluminum...

Click to expand...

Specialized remains the foremost bike for technical & downhill racers. They are somewhat secretive about their alloy, but it an aluminium/manganeze/zinc alloy manufactured to very exacting standards to achieve the most optimum weight and strength possible. They're almost indestructible. A very good frame. But.... with the weight of the motor and battery added in, the extra expense for most people is not worth it. A good steel frame, even from Target or Walmart, for most high-duty eBikes is good enough.

I am scraping the bike, using the front derailleur and the crank.
Will find a suitable frame sooner or later.

Problem is I am in the 3 bills category (weight, 300+lbs), not fat, just stretched out in the 6'+ club!

Yeah, you do need a large frame. No way you'd be ok on a walmart genesis or mongoose frame. They are built for teens.

One option I recently saw done on a genesis frame, they just dished the wheel to the disc side, and put a one speed freewheel on it, making the motor fit a narrower frame. No problem to flex an alloy frame out 5mm, and some have done it to 10mm. Avoid permanent bends to alloy swing arm parts. But you can flex out to 140 mm no problems.

I aint getting no Wally Crappy mart bike.
In time I will find the right bike.
I do not know if any "good" bikes, like from Specialized or Rocky Mountain or the like come in steel or cromo thats full suspension.
Its going to be a long process, in the meantime I am building my ebike up on a Specialized Rockhopper with only front shocks.
Might just sell the thing in the end. Depends on how I like it.

I got a gaint upland with comoly frame for 55usd. but didn't look at the diarailuer , they don't put a good dialrailuer on a cheap bike. My mistake. So that's the clue. It looks like Teslanv's green bike is his new for sale thread.http://www.endless-sphere.com/forums/download/file.php?id=156588&mode=view

Hey I pasted a pic from a different thread a first. Do da Do. I used the car jack it was as close as my trunk. Plus I had to redish my rim. would go to work for JRHolmes if not so far away. Maybe wait for my second wheel build thru.