Bella's bike

It's really nice! Unfortunately not mine -- I rent a bench from a (far more capable) pal who does this for a living!

I can't really understand the advantage of having a large rear wheel if the front is small

Our shopping bike at Omnium HQ is an old prototype with 20" F+R. While there are benefits to the small wheel it's also very obvious it doesn't roll as well as a bigger one.

I can definitely see your point, but for me it feels like it’s the front wheel smashing into things that stops me rolling smoothly, so I can’t see how the large rear would help, because I’ve already been slowed down… if that makes sense? Anyway, I’m not fully convinced, but I’ll let you know after some back to back tests!

I wouldn’t worry about the slight increase in rolling resistance with a mid drive motor anyway. This bike looks so awesome!! V jelly

It does, but even on very smooth roads bigger wheels keep momentum better.
It's not a criticism of your design decision though, and as @MCamb pointed out it is not a concern on an E-bike anyway.

Will the stability not be affected by the wheelbase being shorter due to the 20" rear wheel giving less length behind the rider? The front wheel is already in a 'normal' position, with no extension under the load, which is sitting very high due to the suspension forks. Will there not also be a lot of brake dive with the length of fork travel combined with the high/forward weight over it?

Not criticisms as you're building the exact bike you want, just questions.

stability not be affected by the wheelbase being shorter due to the 20" rear wheel

I'm intrigued to find this out too, I stretched them out for that very reason so the chain stays are ~400mm in the shortest position... not much shorter than they would be with a larger wheel, so the contact patch is pretty well in the same place. I think they look very short because the motor mount encroaches into where they would normally be. I also don't think it will want to wheelie given all of the weight up front and at the motor, but I could very well be wrong!

The front wheel is already in a 'normal' position

Yes, although I have slackened off the HA as much as I dare (while keeping reasonable trail) to try to compensate for getting rid of the extension.

Will there not also be a lot of brake dive with the length of fork travel

I'm also a bit worried about that. The fork is 100mm travel, so it's more than I've seen on most cargos. It does have a lock-out though, and I think if I find I'm using that when its loaded I may end up making something rigid for it, or trying something shorter travel.

Appreciate the comments, and definitely don't read it as criticism... I only wish I'd started the thread sooner (i.e. before cutting tubes!) I suppose I think this is the bike I want, but it's definitely a prototype, so we will see.

Totally agree, with you -- I'm a convert to 29ers (and even 22" BMX), but for this my priority is keeping it as small a package as possible for getting through doorways!

Good stuff.
I think the bike will ride great. The small wheel in back longjohns are really popular here.

9 months since last post, and finally got the Bosch bits through!
Starting to figure out all of the wiring now -- worked out how to seal up and route the main power cable with some off the shelf grommets and a punch.

Also put some finishing touches to the frame like the stay/brake brace -- emulating the best to ever do it, Fastboy with this to match the curve of the rotor (not that it lines up particularly).

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Rack is on...
I think I'm ready for paint now. My plan is to gun blue it, add some white painted details and 2k clear coat over the top.

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Paint.
Had some fun with a cold blue patination and a pot of Humbrol. It came out ok -- the patination was really tricky to manage in my damp garage.

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nice work, very cool. Id love to build something similar. Somehow i missed this thread til now!

Furries Fit Fine
❤️

Not seen this until now, Bella is wonderful and the bike looks cracking. Can't wait to see how it comes together!