Bella's bike

Last year we moved to Sheffield from London, (via Aarhus), and have been struggling with taking Bella (~20kg 5y/o bull whippet lurcher) on our Omnium around the seven hills. Thought I would start a build thread of the 20" e-cargo I'm going to replace it with. (Omnium will be for sale soon too!)

I've decided to go 20" wheel front and rear. I can't really understand the advantage of having a large rear wheel if the front is small, as it just seems to take up more space (which is at a premium in our small victorian terrace with awkward doorways). A 20" Suntour 100mm suspension fork up front (so poor Bella doesn't get rattled around as much). Low stand over with plenty of space for a long dropper meaning my partner can also ride it if needs be (we had a similar setup on the Omnium, but the unnecessarily high/horizontal top tube meant it never quite worked). Grav grav tyres.

In terms of electrics: a Bosch Gen 4, Performance line cargo motor and the 545 externally mounted battery (with the option to add and additional external battery in case we go for a longer tour). Custom stem to get the stack height right (I could potentially do away with this and extend fork's steerer tube but that feels like more hassle/danger) Lights F&R, smart system controls. I've not built an e-bike before so this is a steep learning curve!

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First tubes cut. This is straight gauge Reynolds 631 (motorsport tubing) for the DT, TT and basket/platform arm. It's not light, but this bike has a motor. Then 525 HT, SS, and some nicely butted 631 for ST and CS.

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This thread is already a banger

Ace project, how supple is the doggy chore coat?

Looking forward to seeing this. The Bosch performance line motors are really powerful.

What’s your plan for the crate/box to hold Bella?

Pretty supple after many years of hard grafting in it.

I've not finalised that yet but I don't envisage a time where I would want to remove it, so I was planning to weld a rectangular rack directly to the main frame (probs more 631 plain gauge) with a webbing base. The ply box I made for the omnium is great because I can unclip a side to let Bella jump in/out, but it's 6mm birch and makes the front of the bike pretty heavy and unwieldy, so I was thinking of trying to lighten it by using a tubular frame with Cordura sides. TBC

The motor mount is rank, but this is a prototype. I'd like to do something neater and laser cut out of plate for the next one.

The Bridgeport makes holes nice and easy -- these are for the battery mount, so it kinda matters that they are in the middle of the tube.

The front triangle is almost ready for welding -- I need to work out LOADS of cable routing first though.

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All dogs should wear Carhart.

Dolly says hi to Bella and is keen to see how this goes. She already thinks it’s cracking.

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this is awesome. 2nd battery goes under the down tube?

Hey now, I feel cooler owning the same pick! This project is awesome. What Bosch line you going for?

My understanding is that all of the performance line motors are the same just with different tunes to their power output curves... so I think I'll go for the cargo line because it has a nice high torque start...

Yeah I think that's the most sensible spot... I think I will add the mounts and if it doesn't get used it's nbd. I'd really like it if Bosch would bring out a little water bottle sized range extender that could plug into the on board charging port.

Crumpet in her matching jacket (on the one day of the year it was cold enough for her to need it, she runs too warm for regular use). Now I just need to find the space, funds and trust in the dog for a matching cargo bike.

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Yes yes! Bella took to the Omnium pretty readily with lots of treats. I tend to take it slower when she's with me because she does like to lurch around a bit if she sees a cat...

Bit of a mare yesterday. Managed to neatly mitre the chain stays in the Bridgeport with a slitting saw for the drops and a massive end mill for flattening where they attach to the motor mount, and then promptly squashed one side when I carelessly moved the head to machine the second side. I should have ordered a 5mm end mill (only had 6), waited for it to arrive and done the slots from above, but I was feeling impatient. Lesson learned.

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Good progress over the weekend.

Pulled apart a perfectly good, sensibly sized wheel (anyone need a brand new 27.5 Stans Flow?) to make this ridiculous looking wheel with 145mm long spokes. It's a real hassle building small Rohloff wheels -- they're very fussy about where you're allowed to cross the spokes, and the spoke angle from the hub flange. This is the best solution I came up with: all spoke heads out, and with crosses avoiding the hub cap bolts.

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Also managed to mitre the seat stays. I hated this fixture the first time I used it, but this time (with some more thought and patience) I managed to get these fitted pretty well spot on straight from the mill. It helped that I had a brand new carbide end-mill to machine the dropout slots and avoid fucking around with slitting saws.

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Hi Liam. Sorry I wasn't more available when you were in Aarhus. You seem like a great guy and this project looks great. Makes me want to build more utility bikes.

Hey Mads! No worries! That year seemed to pass so quickly, but I really enjoyed that pedal out and about that we did. I wish I had stuck around a bit more last summer to make the most of the camp out opportunities and the long days though.

Tacked!

Managed to get a decent shift on last night. Can hopefully get the back end tacked over the weekend and then out of the jig to be fully welded.

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And because pictures of tacked metal tubes are extremely boring, here is Bella dressed as Mulder (or Scully?) at a fancy dress party. Which is exactly the kind of thing this bike will be used for.

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Made some good progress over the weekend and Tuesday night.
All fully welded, braze-ons done, and pretty well re-aligned (I put way too much heat into the motor mount and stuff moved a lot -- it's hard sticking a massive casting and thin wall tubing together).
Pics of it mocked up with the fork and a (skinny) front wheel. It's a weird looking bike for sure -- super long and super low.

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nice workshop