Considering build - 20" folding bike

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Jan 28, 2022
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An ebike has gotten me far, but an ebike I can take carry on the bus will take me farther.

Edited - I originally stated I wanted to drop a wheel in this. But, how about 500w mid drive with CVP rear on a belt drive. Can that work here?

foldingebike.png

My other ebike is 48v so I'd prefer to stay with that.
Has anyone modded these folding bikes? Caveats particular to these? Thoughts?


I've come back here to ask because this forum gave me such excellent input on another build I was considering.
And, if the mods prefer for me to post all of my proposals under one thread, pretty please merge these.
 
If you are allowed to take something like that folded up on a bus, many drivers dont know the few that are douche bags may give you a hard time.

20" rim into a small geared hub motor would do you well, look at the spoke calculator to get an idea, if the hub isnt there just pick a close one but 20" should be fine, 16" rims get worse, 14" is a no go pretty much but it all depends on the diameter of the hub.
 
Yep if it gets a hub motor it will definitely be 20" no other way around it.

The bus where I'm at is not a city bus, but a regional bus between towns. They're cool with it. You make a good point though in other places some would have an issue.

What about a mid drive motor on this?
 
A NuVinci/Enviolo hub weighs as much as a hub motor by itself. So you'd be effectively doubling the weight of the motor drive. Watt for watt, you could unlock some more performance with a mid drive, but to what end? Going fast on a rickety small-wheeled bike will only get you in painful trouble. You don't want that.

You can't use a conventional belt drive because your bike doesn't have a split rear triangle. But don't think you'll be opting out of maintenance with a splittable belt-- motor power will knacker any kind of bike drive belt, and you'll be getting used to doing frequent and expensive replacements. Lubing a chain is much easier and cheaper.

I say figure out what top speed you really can't live without (being realistic that slow is actually fast on a folding bike), and use a geared front hub motor that offers that much speed. That will be lighter, cheaper, much lower maintenance, and generally easier to live with.

If you want an internally geared hub, use one. I recommend three speeds, because once you electrify that's all you'll really want. Top gear for zipping around with power in easy conditions, middle gear for helping the motor on hills, and low gear for when your battery is done or you have an electrical problem.
 
From personal experience with several folders, in both mid- and front-drive configurations — take Chalo’s advice, it is spot on. Folders can be great bikes, and electric folders both fun and useful ... but they do not benefit from high power (high torque or top speed) setup.
 
I never rode a folding bike that felt like it had enough integrity to go beyond 15mph.
The one i bought had the thickest and strongest folding latch i'd ever seen, yet still turned poorly and shaked.

The idea of converting it went squish upon the first ride.

Unless we're talking about the highest quality folding bike on the market ( Dahon? Tern? ), i'd have to say the most power i'd put on one of those is a geared hub pushing ~20mph.
 
Chalo said:
A NuVinci/Enviolo hub weighs as...

Chalo thank you so much for this. A big help and so much to consider.

As for power on the bike one problem I see are a lack of options at 48v 20". Everything is 1000w it seems unless you go mid drive.
I think I'm giving up on the CVP option for any ebike... in any case thanks again for your insight!

LewTwo said:
Riese & Muller did it on a 20 inch wheel frame but it is not a folder.
https://propelbikes.com/product/riese-muller-tinker-silent/

Thanks for this. Couldn't get the link to load it would just time out, perhaps I will try again later.

neptronix said:
I never rode a folding bike that felt like...

Thanks for this - I was leaning against doing it but your words here put the nail in the coffin on the idea. Thanks for your input!
 
metaneuralnetwork said:
As for power on the bike one problem I see are a lack of options at 48v 20". Everything is 1000w it seems unless you go mid drive.
I think I'm giving up on the CVP option for any ebike... in any case thanks again for your insight!
There are LOTS of 250, 350 and 500 watt geared hub motors available
 
Yeah, if I were building an e-folder like that for someone, I'd use this front hub motor connected to a 15-18A controller running at 48V, for a top speed in the 20ish mph range. It can be restricted electronically through a KT display if that's too fast for the bike. That's not the lightest or best option, but it's a known quantity, reliable, and cheap.
 
Chalo said:
Yeah, if I were building an e-folder like that for someone, I'd use this front hub motor connected to a 15-18A controller running at 48V, for a top speed in the 20ish mph range. It can be restricted electronically through a KT display if that's too fast for the bike. That's not the lightest or best option, but it's a known quantity, reliable, and cheap.

All right I learned something - running 48v battery on 36v motor through that controller. Awesome.
Now I just need to learn wheel lacing and the sky is the limit.
 
Some of the 20" folders out there are really good bikes, when ridden within their design envelope. Tern makes some nice bikes, Bike Friday makes some nice bikes, Dahon makes some nice bikes. I'm not familiar with the bike in the photo, so can't speak to its ride qualities. But if you are going electric, do yourself a solid favor and start out with a bike that has a ride you really like.

The things that make small wheel folders fun to ride are their quick responsiveness and sensitivity to rider inputs. Other words for those two qualities could be ... twitchy, and easy to crash. Especially some of the BSO folders.

About over-volting. Do it if you want, it won't hurt the motor, and if you are the personality type who will actually electronically limit power it won't get you into trouble. If on the other hand you are like 99% of us ("hey, let's see what this baby can do"!), that power limiting strategy might not work for you.

I over-volted a so-so folder, running a motor spec'd for 36V at 48V. It was fun. For a while. Until the crash. Operator error for sure ... but the contraption I was riding didn't help.

So anyway, my advice for anyone who wants to go with folding-ebike: start out with good bike, electrify it with quality components (like the folder motors sold by Grin), set up for modest power levels. Spend the money to do it right. You could build a fleet of nice bikes for what a day at the Emergency Room costs!
 
The ideal bike for my purpose would actually be a step through 26" aluminum frame with rear suspension. Doubt it even exists.
 
metaneuralnetwork said:
The ideal bike for my purpose would actually be a step through 26" aluminum frame with rear suspension. Doubt it even exists.

I guess elderly poseurs aren't a big market.
 
metaneuralnetwork said:
I'm not trying to be cool it's for a specific task.

Understood. But it's still a small market, and you'll probably have to fend for yourself. I know I do.
 
It does make me remember the Shockster from back whenever that was:

iu14xe31zn921.png
 
Kind of cool kind of, what with its 1" of travel before the tire hits the cross bracing of the frame.
Would not a 200 dollar suspension seat post with a 100 dollar cushioned seat be more suspension, then you could even throw in the handlebar suspension stem along with a suspension fork. I personally never seen a 20" suspension fork, I am sure they are out there.
 
Chalo said:
metaneuralnetwork said:
I'm not trying to be cool it's for a specific task.

Understood. But it's still a small market, and you'll probably have to fend for yourself. I know I do.

Ahhh ok :) sorry I've been on some rough forums in the past. AOL in the 90s and stuff.
 
The 20" rim itself is a 508mm disk not a measly 203mm disk :wink:
or if your lucky 220mm https://www.modernbike.com/disc-rotors+rotor-sizeis220-

E-HP said:
Oooo nice. I want the disc brake version!


You are one old cat metaneuralnetwork, Geocities, audible modems, baud rate, replaying tones into the pay phones for free calls anywhere in the world.

metaneuralnetwork said:
Chalo said:
metaneuralnetwork said:
I'm not trying to be cool it's for a specific task.

Understood. But it's still a small market, and you'll probably have to fend for yourself. I know I do.

Ahhh ok :) sorry I've been on some rough forums in the past. AOL in the 90s and stuff.
 
LOL yeah pretty much.

2600

also... I know we hate foldables, right... but this is intriguing. 26. aluminum. step through...

foldingaluminum.png

edit - check this out... trying to imagine it with a with the seat lowered and taller, less aggressively positioned handlebars. More like a cruiser.
But can a rear carrier be mounted on this?
26alumstepthrough.png
 
Chalo said:
It does make me remember the Shockster from back whenever that was:

iu14xe31zn921.png
circa 1999, 3.2 pounds and adds 3 inches to the wheel base.
oops ... I just ordered one off fleabay :?

s-l1600.jpg


Reference:
https://www.endless-sphere.com/forums/viewtopic.php?t=81014
 
Why not use a bmx bike with 20" wheels, I did a quick check to see if there are any adult bmx or long wheel base bmx and nothing came up. The do have bmx in 22" wheels and 24" https://bmxmuseum.com/forums/viewtopic.php?id=613707
Get some foldable pedals, the handlebars can just swing when you undo the stem bolt.
 
metaneuralnetwork said:
But can a rear carrier be mounted on this?
From your supplied photos I can almost barely make out what looks like 2-3 bosses on the side of the seatstay, just before and after the name "PRODECOTECH." If that's what they are then you should be able to sturdily mount a good weight-bearing rear rack.
 
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