Jay said:
Joseph has suggested 'XXL size BMX frame with a monster long seatpost and
ape-hangers'.
<snip>
Quoted message said:I don't know what 'decent quality BMX frame' means. Let's start at the top
$, and work down if necessary. Keep in mind that I know absolutely nothing
about BMX frames.
BMX frames are not traditionally sized in inches, but by racing
category. This is a custom that has extended even to bikes that are
not used for racing. In order of size, the categories are:
Micro (think four-year-old kid)
Mini
Junior
Expert
Pro
Pro XL
Pro XXL (more or less normal adult size)
There are probably "Pro XXXL" and such frames out there, but there's
no conventional understanding of sizing outside what I have named. If
you are of average or larger adult stature, only Pro XXL frames will
be suitable for your purposes. Some frames are sized in inches, but
the size refers to the top tube length and not the seat tube. Don't
bother with anything shorter than 21.5 inches.
The vast majority of decent quality BMX frames are made for one of two
purposes, but not both:
Racing, or (more commonly)
Freestyle-- which is jumping and other stunts.
There is another discipline called "flatland", which is a kind of
artistic cycling, but those bikes would be of no use to you
whatsoever.
Racing bikes will be lighter, more fragile (but still stronger than
the bikes most of us are familiar with), and longer in the rear end.
They have V-brake bosses mounted above the seatstays.
Freestyle and dirt jumping bikes--variations of the same thing-- are
built to take a beating. They tend to be heavier than full-sized MTB
frames and very compact in the rear triangle. They usually have U-
brake bosses mounted under the seatstays or above the chainstays.
Note that many of these have 14mm dropout slots, for hubs with
oversized axles. If you wish to use a 3/8" or 10mm axle, you'll have
to have stepped washers to take up the difference in size.
Here is an example of the most expensive sort of BMX frame you should
consider buying:
http://www.danscomp.com/211339.php
It's a freestyle bike in a grownup frame size, with a grownup price of
$289 for the frame only. Its dimensions are all quite generous for a
freestyle bike, which is why it's an acceptable alternative to a
racing frame. It has oversized dropout slots.
Here is a racing frame that would make a decent choice:
http://www.danscomp.com/201340.php
It's pretty light, reasonably priced at $199, and fairly long in the
rear triangle for a 20" bike. Here are a couple more of the same
general description:
http://www.danscomp.com/201073.php
http://www.danscomp.com/201122.php
Things to look for if you'd like to use a BMX bike as a commuter:
25.4mm (1"😉 seatpost bore, which will allow a very long seatpost that
won't bend. Consider having a machine shop make you one by turning
down the top of a 1" aluminum rod or thick-walled tube to 7/8" to fit
standard seat guts.
U-brake bosses on the fork. If there are no bosses, you'll have to
use a long reach BMX sidepull caliper (which is a bit like trying to
stop your bike with chopsticks).
Steep seat angle. BMX seat angles vary wildly. The slackest of them
could easily put your saddle behind the rear axle if the seatpost is
long enough for full extension.
Handlebars with a minimum 8" of rise. 8" is the tallest common size
anymore; you may want to add a HeadsUp riser or the like underneath
the stem. The combination of a small wheel size and very short head
tube will put your bars too low unless you take extreme measures. BMX
handlebars are a different diameter than road or MTB bars, and their
stems are all very short, so having tall bars means you can tilt them
forward or back to get the right reach.
Steel frame with relatively long chainstays. This will give you a
fighting chance at spreading the rear end from the BMX standard width
of 110mm to something usefully wider for a multi-speed hub. It will
also allow you to add brazed-on details like a derailleur hanger and
shift cable housing stops.
There is one more kind of bike,now long departed, that might be a good
basis for your commuter. Formula One (or F1) was a sort of BMX bike
with gears for racing on autocross-style street courses. They came
and went sometime around 1990, give or take. Such a frame, if you can
find one, will be much taller than a normal BMX bike and set up for 6-
speed derailleur gearing. Haro, Diamondback, and Redline made them.
Good luck finding a suitable bike.
Chalo
