Pukeskywalker

I've got two little ones on the way (twins) and want to get started building some 20" bikes for them.

I'd love to convert a BMX to a multi-speed drive, but keep it on the cheap side.

Here is a short guide by a father who did something similar:
FAQLoad - Adding gears to a single speed BMX



The author took a Redline Mini Pro LE with a cassette freehub, machined it so that he could fit a addreviated 5-speed cassette on there, then hung a derailleur with a DMR wheel tug with an integrated hanger ($30).

I'm wondering if I could do something similar for less money.

Questions for the experts:

1. Is there an affordable ~$50-$75 out-of-the-box rear wheel that comes with a cassette freehub? I think I could go cheaper w/ beater craigslist BMX + new rear wheel w/cassette

2. Is a walmart Aluminum frame (Magna or the like) significantly heavier than an aluminum frame from a more reputable brand?

3. I'm concerned about the top-tube length on most BMXs I'm seeing. Should I look for a certain type so the kid isn't too stretched out riding?

4. Is there a cheaper alternative to the $30 DMR hanger? A lot of money for a small part like that. I see some cheapo shimano derailleurs with built-in hangers on them, like this: https://www.mpgear.com/rd8165/shimano...FfIF7AodIggArg


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Edit: more details on the guy's cool bike, with more sizing concerns.

"BMXs although having very low stand over height are long in the top tube - even the mini/micro frames. For this reason I had to turn the offset seat post that the farm came with around so I could get the seat further forward. I also had to tilt the handlebars back to further shorten the cockpit. A zero offset post would be best for this application."

https://faqload.com/faqs/bikes/bmx-to...n-redline-mini

198xBMX

Thats cool! Theres been a factory made 2 speed murray bmx on local craigslist. Its called the afterburner, cant get the idea of kids racing out of my head when thinking about it, "OH SXXX, Hes going to hit the afterburner" lol. Anyway

I would just start with some "junk" mountain bike part's, but thats just me. About that top tube/frame length issue you could build a frame around the parts. A good welder can make the frame how you want.

198xBMX

Also, that redline looks like a load of fun!

Pukeskywalker

The Afterburner looks sweet! Yeah I would have loved to have that bike as a kid.