Request for design critique: Mini Velo Cargo Bike

[TroySmith80]

Hello everyone, I've been lurking a bit here and learning from the many very talented builders on this site. I am not a framebuilder but am hoping to attempt my first this winter. Lots to talk about there and I'm not going to bother you with it, at least not right now.

For now, i'm interested in feedback on my design.

(SKIP THIS IF YOU'RE ADD)First, the reasoning and experiences leading up to it. My wife and I each have longtail cargo bikes right now. We like them a lot in many ways, and we love what we can do with/on them, but they are also a pain in the butt in other ways. They take up a lot of space in the garage and can't be hung on the rack with the rest of our bikes. We can't put them on our roof-rack and take them places. They can't be put on a bus rack. For my wife, they are heavy, difficult and awkward to move around and deal with (she's not very strong). They also don't handle as nicely as a normal bike. Lastly, we find that we very rarely use their full cargo capacity, and could get by with less.

So i've been thinking about what would work better. A regular bike with a couple large panniers and a large front basket would do pretty well, but that's too easy! Also, while you can fit a lot of small items in the panniers, it's hard to fit one large item. Front baskets make the bike tip over and make the steering difficult. That led me to thinking about cycle trucks with their frame-mounted front racks mounted low over 20" front wheels. Then i thought why not do the same in the back as well--another 20" wheel and another large and low rack. Some googling revealed that i'm far from the first to think this might be a good combination and i found several bikes that resemble very closely what i was envisioning.

• James Black Cycle Truck
• Kemper Lorri
• EBS Turn (scroll down a little)
• Humble Mini Cargo
• Donkeybike
• Also influences are two of the most well thought out bikes i've come across: Quixote/Clever Cycles Xtravois 2.0 and the Juiced Riders ODK

I contacted a few of these builders and they were able to give me some direction in sorting out geometry. I did a lot of research and found tons of info regarding bicycle geometry but it was almost without exception written assuming a 26-29" wheel size and i was unsure if it could be applied directly to a bike with 20" wheels or if i would need to change things. Researching mini velos and folding bikes provided some help as well, but there is far less information about those than about "normal" bikes.

Anyway, here's my design. Please let me know what is stupid and should be changed or what could be done better. There are a few design compromises i'm aware of but have chosen for important reasons:

• The seat tube is cantilevered WAY out past the mixte style chainstays. This is because very low step through height is critical and because i wish to use a standard 27.2 x 350mm seatpost. I'm thinking of using a straight guage 4130 tube 1-3/8" x .095" (34.9 x 2.4 mm) tube for the seat tube, with a sleeve in the top 4-6" to fit a 27.2 post. This is one of the things i'm unsure of.
• The chainstays are abnormally long. This allows for an e-assist battery to be mounted between the seat tube and the rear wheel, and also allows for lots of heel clearance for panniers and other rear loads.
• Racks: Bikecad only displays relatively standard racks. These are just placeholders for whatever rack design I eventually decide on. The front rack will be frame mounted (not fork) and both racks will be removable so that they can be replaced with a better design or a different modular accessory.

I'm hoping the bike can be fairly suitable for both my wife (5'5") and I (6'0"). I'm thinking of using a Montague Octagon extendable steer tube to allow for quick adjustment of handlebar height by several inches. I had thought about using Workcycles' Adaptive Seat Tube design as well, but have decided against it for now, mostly for the sake of simplicity since i've already got a fairly unconventional build ahead of me.

Wheels	20"
ETT	560
ST C-T	530
Est BB height	265
CS	465
HT Angle	73.5
ST Angle	71
Fork offset	30
Trail	41
HT Length	240

These first two pictures show the bike setup for my wife's height, the third is for my height.

[Guillaume]

Hi Troy,

Nice project!

I really like what the EBS people are doing in Japan. I'm looking up their blog a few times a week.

Take a look at the cargo bike I did with 20'' wheels : https://plus.google.com/photos/11759...705?banner=pwa

It was built for an engineer and I don't like a few features that he'd made me put on it but I'm really proud of the parts I did (geometry, tubing choice and fabrication). The XTRAvois 2.0 was an inspiration for it. I know Jon from Quixote and he answered a few of my questions along the way.

For the front geometry I used a 71deg HT angle and a 52mm raked fork giving a ground trail of 29.4mm. Handling is great with and without cargo.

I'm not a fan of the cantilevered seat tube although 2.4mm is quite thick and should hold fine.

[TroySmith80]

Hi Guillame,
I'm not sure why i never responded to you here, but i know i commented on your design in another thread somewhere. I took some inspiration from it as well. Thanks for your feedback. Other projects and problems keep popping up and preventing me from spending much time on this... i guess that's life. I'm still planning to get to it though.

[Guillaume]

Hi Troy,

welcome in the life of bike builder with other obligations (family, day work...) things happend every now and then!

Keep us posted on the developpment of your project.

[Too Tall]

Troy, I am not a builder I'm just a guy who rides bikes alot ;) The project is OUTSTANDING and I do get what you are attempting. I'd be remiss to not point out the fact you propose to replace your longtail cargo bikes (heavy, hard to manage for the wife, can't rack them etc. etc.) with another bike that is going to also be heavy and hard to handle for a small woman. You've solved a couple issues regarding racking it however when loaded you won't be able to lift it onto a citybus rack maybe?

[TroySmith80]

Good points, Too Tall. Perhaps there is no (affordable) way around the bike becoming quite heavy if i want it to have lots of cargo capacity and e-assist. My wife probably still won't be able to lift it, but it will be easier for her to maneuver, simply by being shorter. Still not as easy as a regular bike, but easier than a car! At least i will be able to put it on the roof of our car if needed, and I'll be able to hang it on the vertical bike storage rack in our garage. The long bikes can't do either of those. Switching to a geared hub-motor instead of a direct-drive motor will save quite a bit of weight too.

I'm a fan of either having the bike baskets removable, so they can be taken in the store shopping with you, or of using cloth shopping bags in the baskets, so that those bags are taken in the shop with you. In either case, if riding a bus, i suppose you would have to remove the bags/baskets from the bike, and carry them on the bus. Otherwise, even a strong person might have a hard time getting the bike on the bus rack. My town is small and there is no need to use buses. That consideration is one that i had in mind for more people in larger cities, or in suburbs of larger cities, but it won't be important for my wife and I.

Thanks for the feedback!

I just discovered the Royal Enfield Revelation, what a gorgeous design! If you look closely, the construction is very rough and unattractive. But if one were to use the same lines but put a little more time and effort into the joints and details, it would be a beauty. I may go for something more like this.
PICT0201.JPG

[TroySmith80]

Found somebody building pretty much the same thing. Scroll down a little, It's not a bicycle, it's a Demonchaux: Design Portfolio

[Guillaume]

Indeed, the Lafayette's are nice bikes.

Thanks for sharing this.

[Too Tall]

Right on. That's a great design.

I like leaving the racks on the bike and using BaileyWorks Bags (I'm a fan) to fit.
Love it man, keep the project going.

[one60]

interesting project...have you considered the gruber assist electric drive which is housed in the seat tube? (this is the E-assist Cancellera was accused of using). That approach seems like a great way to keep the frame design & final look really clean & simple. Then there's the added bonus of removing the stigma of the e-assist motor from site but blasting past others laboring with their packages!

[TroySmith80]

I hadn't considered the Gruber. I didn't really know much about it. It is a clean package but i don't like solutions that drive the pedals. Seems like it would be awkward. I'd like to try one though.

I'm not at all worried about the "stigma". My wife and i currently have electric cargo bikes. There's really only been one or two friends who have given me any grief over it, and i'm not bothered at all. The rest all love them. It would be different if my mountain bike or my roadbike were assisted. When i ride those, i'm riding to ride and i intend to work hard and sweat. When i ride my town bike, i'm riding to get somewhere and i'd like to get there quickly, easily and without needing a shower. So to me, there is no stigma regarding assisted commuter/utility bikes. I think e-assist will be one of the best things to happen to bicycles in a long, long time. It will probably lead to a change in the way our cities are built, because it will get more people using bikes.