Frame Sizes

\\¯`·.¸biz¸.·´¯/ said:

My question is: Are dual susp bikes measured differently? ie are they
deliberately shorter for off-road purposes, or am I just looking in the wrong
places?

There are very few "standards" in the bike business, and "bike sizing"
is one clear example.

The "size" measurements all start from the center of the bottom
bracket (or crank bolt, if you prefer), and run along the centerline
of the seat tube to:

a) center of the top tube (the most useful if you're cutting tubes to
build frames, but kinda meaningless to the rider since he/she doesn't
really care where the center of the tube is)

b) top of the top tube (this one is IMHO the best since it tells you
where the part of the tube you need to worry about is located)

c) top of the seat tube (this one makes no sense at all, IMHO).

I suspect the thing that's confusing you is that the FS bikes tend to
be "smaller" from a frame measurement perspective because the bottom
bracket is higher (otherwise you'd be dragging your cranks through the
mud when the suspension compresses). That means that a given size
rider will ride a "smaller" FS bike than he/she would a hard tail.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

\\¯`·.¸biz¸.·´¯/ said:

Going by traditional sizing methods to check which size of bike I'd need;
having a long inner leg measurement I find that a 21" or 22" would be
about the correct size.

Not sure what you mean by traditional. If you mean using some goofy
math against your inseam to pop out a frame size, well, don't do that.

The first measurement you should look at to compare frames is effective
top tube length. If a bike is close to the right length for you, swapping
stems and moving the saddle around on the seatpost clamp can help you
make the fit perfect. If the bike is the wrong length by more than .75"
or so, there's only so much you can do. Seat tube height is really a bad
measurement to use to compare bikes (tradition be damned) since you can
"fix" the vertical fit just by changing seat height, and lengths vary
by mfger.

Full suspension bikes don't necessarily have a complete "seat tube", so
often the sizing is going to S, M, L, XL. And that makes a TON more sense
than talking about a 19" bike (when one mfger's 19 has a 24.25" effective
top tube and another mfger's 19 has a 23.5" ett).

Since you admit that you are something of a newb, here's the best advice
for you. FIND A GOOD BIKE SHOP. Not just a pretty shop that has the brands
you like, but a shop that has people who KNOW bike fitting. Especially
if your body proportions are atypical, you need the help of someone who
knows how to fit people to bikes. In person. And then you need to test
ride many bikes.
--
Tom Purvis - http://www.arkansasvalley.net/tpurvis/
"The whole problem with the world is that fools and fanatics are always so
certain of themselves, but wiser people so full of doubts."-Bertrand Russell

"Mark Hickey" <[email hidden]> wrote in message

Quoted message said:

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

"Tom Purvis" <[email hidden]> wrote in message

Quoted message said:

--
Tom Purvis - http://www.arkansasvalley.net/tpurvis/
"The whole problem with the world is that fools and fanatics are always so
certain of themselves, but wiser people so full of doubts."-Bertrand Russell

Thanks guys, advice taken on board.
cheers
biz