Donor Bike and Conversion Kit FAQs and Figures

[bws308]

To minimize your work and the cost of extra parts look for the following in potential donor bikes:

1. low top tube, preferably at or below the top of the tires (check out women's and large kid's models too).

2. braze-on cable guides that are on sides or bottom of top tube, not top of tube or may interfere with position of seat base bracket and require removal by hacksaw and file (clamp-on cable guides are preferable and have complete housings).

3. front brake should be linear-pull (V-brake) or caliper, not a disc. Since the fork will be rotated 180 degrees (to maintain rake/trail geometry) a disc brake's attachment point would then be where the freewheel/cassette and derailleur will be located (would require special bracket to re-locate brake, and must also move the disc).

Look for a front brake like the photo at left, not the photo at right (http://en.wikipedia.org/wiki/Bicycle_brakes):

(all photos courtesy of Wikimedia/Wikipedia as linked from Wikipedia articles)

alt="linear-pull, or V-brake" alt="disc brake"
by Arnold Reinhold_____________by StromBer

4. threadless stem or you'll need to buy an adapter (note: the stem extension tube and longer fixing bolt are included in the kit).

Look for a stem like the photo at left, not the photo at right (http://en.wikipedia.org/wiki/Stem_%28bicycle_part%29):

alt="threadless stem (Aheadset)" alt="threaded stem (quill type)"
both photos by Andrew Dressel

5. seatpost must be the kind with a tapered top and separate clamp, and not a clamp that's partly integrated on the seatpost, else you'll need to buy a new seatpost of the proper kind to fit the seat tube of the donor bike.

Look for a seatpost like the photo at left, not the photo at right (http://en.wikipedia.org/wiki/Seatpost):

alt="standard tapered seatpost" alt="integrated seatpost clamp"
by Ralf Roletschek_______________by Andrew Dressel

6. front derailleur is clamp-on type for 34.9mm tube, or you'll need to buy one, or buy a braze-on adapter clamp, or just use a single chainring.

7. bottom bracket shell on conversion kit is 68mm wide so the donor should match, or you'll need to buy a 68mm bottom bracket.

8. rear wheel axle dropout width is 135mm (inside), or you'll need to use spacers, need to file the axle or buy a new rear wheel to fit the conversion kit's brackets which widen 100mm fork dropouts to 135mm (matching the kit's chainstays and standard 26" wheel axles).

9. front wheel axle (fork) dropout width is 100mm (inside) to fit the conversion kit's brackets when bolted to a 135mm wheel axle (note: most 26" wheel axles are 100mm front and 135mm rear but other wheel sizes may, and probably will, vary in axle width).

If the donor meets all of the above specs, you may only need to buy some new cable housings, and zip ties or cable clamps to attach the cables.

Full step-by-step instructions
http://charles.plager.net/documents/cruzbike_conversion_instructions.pdf

Putting the drive wheel up front and adding a quick release axle to rear wheel (the original front wheel)
http://www.cruzbike.com/putting-drive-wheel-front

Axles, Hubs, Quick Releases and Adapter Brackets
http://www.cruzbike.com/conversions-axles-hubs-quick-releases-and-adapter-brackets

Stem adapter (from threaded quill type to threadless)
http://www.cruzbike.com/stem-adapter-conversion-kit

Front derailleur size
http://www.cruzbike.com/front-derailleur-bracket-too-small-fit-around-cruzbike-tube

Front derailleur cable installation
http://www.cruzbike.com/fd-installation-creating-proper-directional-pull-fd-function-using-tube

Bottom bracket specs
http://www.cruzbike.com/conversion-kit-bb-specs

Bottom bracket plugs
http://www.cruzbike.com/where-do-you-findbb-plugs

Bent seatpost (layback style)
http://www.cruzbike.com/trek-y3-igh#comment-18060

Homemade seatpost
http://www.cruzbike.com/cheaper-seat-post

Homemade headrest
http://www.cruzbike.com/silvio-headrest-nice-comfy-cheap

Timelapse video of a conversion
http://www.youtube.com/watch?v=qu-9yhDiqPw&feature=share&list=UUwzNpm5dokD8c2E178bZ7Bw

 

[John Tolhurst]

Whoa! thanks very much for

Whoa! thanks very much for this!

 

[Doug Burton]

I think this needs to be a sticky post at the top of this forum

Nicely compiled. Thanks a lot for the research.

 

[bws308]

You're welcome, John ...

... and here's to a successful and easy build for all the future Cruzbike converters reading this now.

Thanks to you, John, for all your efforts in bringing your ideas to market, and thanks for making this a "sticky" topic.

If anything is incorrect in the first post, please let me know either here or by this website's email system. The opening post will be edited whenever other relevant forum topics are found to link from here.

It's been an interesting month reading many of the forum entries and saving the most helpful as links for future reference, from which it was relatively easy to create this forum topic.

Cheers, Brian

 

[bws308]

And thanks to you too, Doug!

Your blog and creative engineering in conversions is great support for the community and the company.

Cheers, Brian

 

[mikexpress]

Got me going ...

Brian,

Your exceptionally timed article got me to take the plunge and make the purchase this evening of a conversion kit. I know it won't be easy for me having limited experience compared to the majority of the community here, but I certainly appreciate the support thus far. Thanks again, and hopefully this foray into the recumbent world will be an interesting one ...

Regards,
Michael

 

[Charles.Plager]

Hi bws308,
Very nicely done.

Hi bws308,

Very nicely done. And the pictures are a great idea, too.

A couple of comments:

* I would lessen the warning about threaded forks. Ahead adapters work fine.

* Likewise, the seatpost warning. I agree an integrated seatpost won't work, but seatposts are cheap and easily available.

* Your disc brake warning could be made even stronger: If the fork has both disc brake tabs and v-brake brase-ons, you'll be able to use the fork after cutting off the tabs. If there are no braze-ons for a v-brake, then the fork won't work. (I don't know of anybody who's ever gotten a conversion kit to work with a disc brake up front.)

Cheers,
Charles

 

[bws308]

Hi Charles,
Thanks for your

Hi Charles,

Thanks for your comments and for the copy of the full instructions posted in your blog.

Just to clarify: this topic was not meant to be taken as a warning against using any specific donor bike, nor as a prioritized list of what to look for when considering a conversion. This topic is only meant to point out all the things that might cause unnecessary extra efforts, expenses and time if you're not careful in choosing a donor bike. In other words, it's mainly meant for those with little patience, time or mechanical ability, and frugal people. However, those with little patience or time probably won't ever read this topic. So, it's really for frugal people and those who are mechanically-uninclined but still somewhat handy with a wrench.

In my searching, there seems to be no "perfect" bike that meets all the specs given above, especially the stem and seatpost. Most low cost bikes have the "wrong" stem and most higher-cost bikes have the "wrong" seatpost (and often the "wrong" brake). Of course, everything has a work-around, but many people would prefer to just get the job done and not tinker for hours or search for parts and wait for delivery. I know I'm one of those people, though Doug B. is probably not!

I'm wondering if Cruzbike could add a bracket and a couple hose clamps to attach the seat back to any kind of seatpost.

For now, I think I'll just boldface the opening line: "To minimize your work and the cost of extra parts..."

Cheers,
Brian

 

[Charles.Plager]

Hi Brian,
I think you've done

Hi Brian,

I think you've done a really nice job summarizing the situation. For seatpost and threaded/non-threaded, you are right, it really is a case of "a little bit easier." For brakes, it's more important as one could easily end up with a fork that would not work (and having to get a new fork is definitely a bigger deal than getting a new seat post).

I'm sure some sort of bracket could be manufactured to use the integrated seatposts, but given the cost to do so compared to the cost of buying a regular seatpost, I would guess the business case to do it isn't there (for now, at least). But I could be wrong about that.

Cheers,
Charles