Bike Friday Family Tandem -> 2 wheel drive IPS Cruzbike tandem?

[richa]

Has anyone looked into converting a Bike Friday Family Tandem into a cruzbike tandem? Or have any thoughts or ideas on the feasability of such a conversion.

For those unfamiliar with it, it looks like this:

At minimum it would require a conversion kit, another rear wheel (for the front), an extra cruzbike seat, and different seatposts. But since these tandems can be found used for < $1000 is seems like a reasonable way to get an "inexpensive" recumbent tandem.

Any thoughts or opions?

 

[Charles.Plager]

I don't see any reason why

I don't see any reason why the front shouldn't convert just fine.

You can even imagine putting on a second Cruzbike seat in the back and having the stoker use the original crankset for the pilot. I'm not convinced that would work, but it might (and it would be pretty sweet if it did). You'd probably want different handlebars for the stoker...

It's not completely crazy and could be very cool.

Cheers,
Charles

 

[John Tolhurst]

reckon you could fit three

reckon you could fit three poeple on that sucker

 

[Doug Burton]

Tandem frame conversions...

I have been wanting a Cruzbike tandem for some time. We have a Vision R82, but the drivetrain is 10 miles long and pretty inefficient, and the bike is over 9 feet long - I don't have anything that will transport it anymore.

I have considered building a compact Cruzbike tandem, 406 or 451 wheels, where the stoker sits over the back wheel. I received a 9-foot-long piece of 80/20 aluminum extrusion for Christmas (yes, my Christmas presents tend to be a little strange) to build a frame jig for this project.

http://www.8020.net/

The basis of this frame is a BMX bike, where I would cut the bottom bracket area out to use as a "lug set" onto which I would weld longer tubes. The tube angles on a BMX frame seem to be just about right.

What I've learned about converting conventional tandem frames is that the distance between the captain's bottom bracket and the stoker's seat post doesn't allow for a long enough x-seam; generally this dimension is 22 - 24". You quickly reach a point where it's easier to build a frame than hack up an existing tandem.

Addtionally, the captain's seat back needs to be ahead of the stoker's crankset BB center, to allow for stoker knee clearance. The stoker Bb also has to be high enough off the ground to prevent pedal interference when leaning into a turn.

I have also considered using the Zox square tube tandems as a starting point, as they are pretty easy to build, relatively speaking, but fairly industrial in appearance.

Interested in any thoughts anyone has.

Cheers,

Doug

 

[MrSteve]

Interesting!

Tandems are not for me.
I've ridden as a stoker on one and, for a lot of reasons, I'll never ride one again.

With that said, they LOOK fun -and I've been passed by one fast couple riding their D.F. tandem.
A good tandem bicycle is it's own pace-line.
Recumbent tandems ought to be pretty fast!

My suggestions?

Invest in some good-quality, straight-grained 2x4 lumber and a panel
of void-free 1/2" plywood: I prefer Baltic Birch.
With wood, you can mock-up functional bikes pretty quickly and easily.
Especially if you bolt the frame elements together.

Bear in mind, I prefer building in wood, so I'm prejudiced.

At least, consider building your full-sized templates in cardboard and testing for fit,
before committing to building a wooden, metallic or composite final frame.

A clean-slate design would be best, I think.
Modifying an existing bike will give you experience... but I'm pretty sure that
your fresh, original design, incorporating a Cruzbike drivetrain, would work best.

-Steve

 

[Jerrye]

Steve has a great point

Mock up in wood, that is.

Used to have a customer in NC that would first mock up in wood anything he planned to build from steel. He built full size, not to scale, as he wanted to see full functionality before putting torch or welder to steel. His reasoning? Wood is cheap and easy to work.

I never saw him have to do any major revisions in his final builds, only minor adjustments. He saved a lot of money and effort doing this.

Seeing the pine and aluminum conversion has my mind working overtime...

 

[Shawnt]

Adding a longtail onto a BMX/Cruzbike for a tandem?

What about starting with a BMX, adding the Cruzbike kit, and then going the other way and adding an Xtracycle kit to get a longtail for mounting a seat? Or another way (and more expensive) would be to start with an Xtracycle bike and add a Cruzbike kit. I have no real idea of needed dimensions, just a few ignorant ideas. I was even thinking that the stoker could be in more of a crank forward position to get a bit more height to see over the head of the captain and be in a bit more vertical position if horizontal space was too limited. Anyway, I cannot build one at this time...