Converting a Kids Bike to Adult use?

[ijeff]

I had an idea... while considering buying a small folding bicycle recently, because of ease of transporting in a vehicle, I thought "why not take a 20" kids bike, add a high seat post, and higher stem and handlebars and use it for my riding!" I like the folding compactness, but its not necessary... Just something small and light to take in and off a rack or from a inside a van/suv.

I'm 6' tall and weigh about 190 lbs. Would this work? I need a bike for mostly recreational riding when on vacation.

It would still be small and possibly lighter than some full size bikes.

Any Comments?

[juan162]

ijeff,
I have contemplated this myself and even had a BMX frame that I was going to start work on. It is definitely possible, but it doesn't necessarily mean that it is easy, cost effective, or the best option. The first and biggest problem is going to be getting a seatpost that is long enough for the bike. You probably won't be able to find one "off the shelf" so you'd have to do some fabricating to get the right height. The same may be true about the stem, but in my experience it is easier to find parts to raise a stem to a proper height. I've seen a couple similar conversions of BMX bikes on

http://www.fixedgeargallery.com/

One of them was a really nice looking ride that a guy made for his bike messenger job. Most importantly, know going in that it will require some time to source parts and fabricate. If you enjoy doing work like this, I would say go for it. The only reason I abandoned my project is that I have been pouring all my time and money into my Raleigh Twenty project bike.

[trentschler]

In addition to the appropriate finding parts, as juan162 noted, the frame and its components may not be nearly strong enough for a 190-pound adult. BMX bikes are certainly meant to take a pounding, but most kids' bikes will be used by, well, kids, weighing 100 or more pounds less than you.

[randya]

ZooBombers do this all the time, with kids bikes. I've got two girl's Huffy 20" bikes that I've put long stems, long seatposts and banana seats w/ long hoop braces on. I've also upgraded the wheels and tires to BMX wheels and tires, added a rear handbrake in addition to the original coaster brake, and regeared them with larger chainrings and longer cranks. While it is true that BMX bikes are probably stronger, I've ridden a couple of hudred miles on both of these bikes with no structural problems. I'm 6'2" and weigh 175#. One of the bikes was originally free, the other cost me $5 at a garage sale. I've invested about $75 into each of them.

[LittlePixel]

Thoughts on your proposition:
1: Reach - if you do this you'll find your knees in the bars so you'll need a long horizontal stem which may make the steering a little squirrely and probably one of those bmx seatposts that arches backwards so you can optimise the amount of space for your manArms™

2: Bottom bracket - kids have little legs so you'll probably find the BB is lower and with your legs at full extension you won't get the most efficient sweep with your legs.

Other than that it's a good idea. I'm only 5'5" and have thought along the same lines. The rare Mongoose Moosegoose BMX bike is a good base as it has an extra tall frame aslong as you don't let any die hard BMXers see you butchering it (there's a thread on here somewhere but search isn't working today) and you could check out what Tony Rentschler's been doing with his beautiful custom 20" adult bikes...

The other thing you could consider is getting a slightly bigger 24" BMX cruiser frame which is like a normal BMX that's been put on a photocopier and blown up by 25%

Moosegoose (http://www.rydjor.com/bikecollection/1979mon.htm)Rentschler's Minibikes (http://web.mac.com/w.rentschler/iWeb/Bicycle%20Site/Compact%20Bikes.html)