I’m only 5’8” on a good day and if I slide to the back of the seat I can pedal one of these things, it’s not optimal riding position by any means but I could pedal the thing a couple miles if I needed to to avoid a walk of shame. On bike 2 I already switched out the crankset to a nice Redline one I had lying around and a 38T BMX chainring. I will be switching out the crankset on the bike Mike is working on to a nice Raceface set I have sitting around, the crankset that came on the bikes stock were a pressed on steel chainring, actually pretty decent....for a steel one.gogo wrote: ↑Mar 03, 2018 1:39 pmThe frames are stout, but too small for many.
That swingarm has a common pivot bearing and can be mounted onto other, larger, frames. The pedal shaft could also be utilized in a DIY rear suspension longtail.-
I've often wondered if a similar aftermarket midrive swingarm would be a financially viable product.
I would think somebody would want them, they could be improved too, disk brake mount for starters.
The bikes have threaded bottom brackets, standard 1 1/8" headsets but one thing to keep in mind is the head tube is a full 9" long so you just about have to use a brand new fork with long uncut steerer tube. There is probably plenty of room for a 2.8 or 3.0 bike tire in the swingarm without a motor in there but in my case I'm going to be limited to the 2.35 Aiken's due to where the motor sits. There is a 2.25 on there right now and there's a pretty good amount of clearance left.JamesG wrote: ↑Mar 25, 2018 5:36 pmFirst post here, though I've been lurking and reading the forum for a year. Now that I'm looking to build an Ebike rather than buy another, the Mongoose 24v450 has been popping up as a great candidate for my intended usage. As I've been researching the bike this thread keeps showing up. I think LightningRods and the owner could probably answer most of my questions before I decide to drop money on a donor bike.
BB size? Is it press fit(BMX style) or threaded? It appears to be threaded in the photos, but I'm not sure.
It is a 1.125 threadless steer tube, correct?
Is there clearance for a 2.5" wide rear tire in the swing arm?
What is the drop-out width?
What is the stock front sprocket tooth count?
Questions for LightningRods:
If the motor was mounted the opposite direction(right side drive) and set up to drive a trials type crank sprocket, like a conventional mid-drive, would one of your "Big Block" motors fit?
What's the optimum RPM for that motor and at what voltage/amps is it most efficient?
Which Surly rear hub did you use?
Do you know of any "dual disk" hubs that would fit the swingarm?
So here's what I was thinking:
Swap the front fork for something better(used Rockshox or equivalent), as well a better rear shock.
Adjust fork height for level ride.
Stretch the swingarm 2-3" to allow for slightly taller(22") 2.50x17 moped tires(obviously on matching rims) and slightly longer wheelbase(stability).
Big Block driving a trials type crank sprocket, driving either freewheel or a fixed 6 hole sprocket dependent on final gearing needs.
Rear disk brakes.
I'm not looking for a 50MPH+ bike. I'd be fine with only 40-45 on flat ground if it meant being able do 25 up hills easily. That would work out to about 610 rear wheel RPM, or a 6.5:1 reduction from a motor speed of 4000RPM with the proposed 22" diameter moped tires at 40mph. With that much gearing, and a Big Block, hills should pose no problem. The wheelies should be fun as well
Anything I'm missing?
That's my biggest concern. I was pretty confident that if I tossed the pedals/chainring in favor of MX foot pegs, one would fit. I want to avoid that however. I still want to be able to ride it on the street some times and pedals are kinda mandatory.LightningRods wrote:...I think you could squeeze a Big Block in there. I’m not sure that you could get clean chain runs from the motor output to the chainring
At around 5Kw and 4k rpm the torque with proper gearing should easily meet my goals of 25mph up hill, so that's good to know.LightningRods wrote:I think it’s best at 72v 60A. It will run at 80A for quite a while...It makes 62 rpm/volt.
I missed that part while reading the thread the first time. I guess my only choice is to go new and expensive, or with one of the less expensive "China" forks on the market.Raisedeyebrows wrote:The bikes have threaded bottom brackets, standard 1 1/8" headsets but...you just about have to use a brand new fork with long uncut steerer tube.
That's good to know. I think 2.50 is about the sweet spot for most ebikes. I've owned 2, and ridden quite a few fat ebikes. Under 27.5, anything over the 2.50 width kills handling in my opinion. Not to mention the rolling resistance if you do get stuck pedaling.Raisedeyebrows wrote:There is probably plenty of room for a 2.8 or 3.0 bike tire in the swingarm without a motor in there