Correct Top Tube vs. Correct Frame Size

With a size 49 frame, presumably this frame has a sloping top tube -
which would make the handlebar height not as bad as it first seems. A
size 49 with a old-school horizontal top tube would have a rediculously
short head tube.

I'd make some careful measurements of the actual frames involved.
Different manufacturers measure things differently - you might find
that the 49 from one maker and the 52 from another are almost identical
in real life. Even if they are measured exactly the same, that's only a
one inch difference - pretty insignificant.

Before investing in a new bicycle, I'd STRONGLY suggest getting a
professional fitting. That way you can actually try out different
combinations and get things correct. Many good shops will waive the
$150 or so fitting fee if you end up buying a bike from them.

RP10128 wrote:

I need a bike with a top tube of about 50.5 cm. To get a top tube of
that length, I need to get a frame that is one or two sizes too small.
That is, I would have to get a 49 cm. frame, whereas my inseam would
indicate a 52 cm. frame. My LBS says that it doesn't matter that the
frame is so small, but this strikes me as being counter-intuitive. Is
the LBS right? Should I get the correct size frame and install a very
short stem?

Peter Chisholm replied:

Problem with a too small frame is the head tube is short and then the
hbars will be very low.

That used to be the primary concern, back when most bikes used the same
top tube length for all frame sizes, and tall stems were not readily
availalable.

This is no longer the case.

Most newer bikes come with threadless forks, with the same length
steerer supplied for all sizes, so if you don't cut it down too short,
you can get the same handlebar height on any frame size, just as you can
get the same saddle height on any size.

For threaded systems, tall, high quality stems are now readily available.

I've been through all of this personally, because like RP10128, I have
very long legs and short torso for my height.

I'm most comfortable on a frame with a 22" top tube, though I can stand
over a 61 or 63 cm frame. For cyclists proportioned as 128 and I are, a
"smaller" frame with a tall seatpost and stem give the best fit short of
a custom frame.

See my article on Frame Sizing: http://sheldonbrown.com/frame-sizing

Sheldon "All Legs" Brown
+-------------------------------------------------------+
| Military conscription is the worst form of slavery. |
| A more enlightened age will consider it a War crime. |
+-------------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

In article ,
Pete wrote:

Keep in mind that the smaller the frame, the lower the handlebars will be.
For example, you probably wouldn't be able to get them anywhere near saddle
level, because the saddle will be that much higher in relation to the frame.
Pete

Unless you retain more of the steerer tube on a threadless fork, use a
stem that is not the classic 7-shape, use a taller threaded stem....
--
a href="http://www.poohsticks.org/drew/"Home Page/a
In 1913 the inflation adjusted (in 2003 dollars) exemption for single people
was $54,567, married couples' exemption $72,756, the next $363,783 was taxed
at 1%, and earnings over $9,094,578 were taxed at the top rate of 7%.

On Fri, 29 Jul 2005 10:25:29 -0600, (Drew
Eckhardt) wrote:
In article ,
Pete wrote:

Keep in mind that the smaller the frame, the lower the handlebars will be.
For example, you probably wouldn't be able to get them anywhere near saddle
level, because the saddle will be that much higher in relation to the frame.
Pete

Unless you retain more of the steerer tube on a threadless fork, use a
stem that is not the classic 7-shape, use a taller threaded stem....

With threaded, it's fairly easy. With threadless, not so much. 'Retaining
more of the steerer tube' only goes as far as the thing was originally,
after all.

Jasper

On Wed, 27 Jul 2005 19:52:31 -0500 RP10128 wrote:

Should I get the correct size frame and install a very
short stem?

That's exactly what I would recommend. To my mind, that's why stems
are made in different reaches.

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
-----------------------------------------------

In article ,
Jasper Janssen wrote:

On Fri, 29 Jul 2005 10:25:29 -0600, (Drew
Eckhardt) wrote:
In article ,
Pete wrote:

Keep in mind that the smaller the frame, the lower the handlebars will be.
For example, you probably wouldn't be able to get them anywhere near saddle
level, because the saddle will be that much higher in relation to the frame.
Pete

Unless you retain more of the steerer tube on a threadless fork, use a
stem that is not the classic 7-shape, use a taller threaded stem....

With threaded, it's fairly easy. With threadless, not so much. 'Retaining
more of the steerer tube' only goes as far as the thing was originally,
after all.

The existence of riser stems seems to be a little-known fact in
cycling...

http://harriscyclery.net/site/page.c...=49&SKU=SM2344

That's...different.

This one's kinky:

http://harriscyclery.net/site/page.c...=49&SKU=SM4818

It does whatever you want it to. Adjust it. You know you want to.

In truly desperate circumstances, there is this:

http://sheldonbrown.com/harris/stems/index.html#raisers

But with uncut forks going for $30 and up on eBay, this isn't a big deal.

What?

--
Ryan Cousineau http://www.wiredcola.com/
"I don't want kids who are thinking about going into mathematics
to think that they have to take drugs to succeed." -Paul Erdos

On Sat, 30 Jul 2005 04:47:12 GMT, Ryan Cousineau wrote:
In article ,
Jasper Janssen wrote:

With threaded, it's fairly easy. With threadless, not so much. 'Retaining
more of the steerer tube' only goes as far as the thing was originally,
after all.

The existence of riser stems seems to be a little-known fact in
cycling...

I wasn't talking about going up 3 or 4 inches. If you get a seriously
mismatched frame, you're more likely going to want something like a 20 cm+
stem.

But with uncut forks going for $30 and up on eBay, this isn't a big deal.

As I say, 'uncut' only goes so far, and of course if you have a *good*
fork to start with (let alone a good suspension fork), you're screwed.


Jasper

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In article ,
Jim Adney wrote:
On Wed, 27 Jul 2005 19:52:31 -0500 RP10128 wrote:

Should I get the correct size frame and install a very
short stem?

That's exactly what I would recommend. To my mind, that's why stems
are made in different reaches.


_ There are worse things, but either a very short or very long
stem will make the bike handling "different". You'll adapt after
a while, but IMHO top tube length is much more important that
down tube length, IF you can get the handlebars in the correct[1]
relative postion to the saddle.

I can't quite find it at the moment, but there is a fairly
interesting article about bike fit at the Hampsten bike site,
in particular it talks about the appropriate stem size for
a give size frame.

http://www.hampsten.com/index.html

_ There's lot's of other interesting stuff there as well.

_ Booker C. Bense

[1]- i.e. the one that you like best.

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In article ,
Jasper Janssen wrote:

On Sat, 30 Jul 2005 04:47:12 GMT, Ryan Cousineau wrote:
In article ,
Jasper Janssen wrote:

With threaded, it's fairly easy. With threadless, not so much. 'Retaining
more of the steerer tube' only goes as far as the thing was originally,
after all.

The existence of riser stems seems to be a little-known fact in
cycling...

I wasn't talking about going up 3 or 4 inches. If you get a seriously
mismatched frame, you're more likely going to want something like a 20 cm+
stem.

Once you are building a non-BMX bike with an 8" rise, you are into
serious freak-show territory, threadless or not. Indeed, For a flat-bar
road or MTB that, for some reason, needed 20 cm of rise, I probably
would recommend a BMX bar.

But with uncut forks going for $30 and up on eBay, this isn't a big deal.

As I say, 'uncut' only goes so far, and of course if you have a *good*
fork to start with (let alone a good suspension fork), you're screwed.

Okay, look: it's possible, I suppose, for a rider to be in possession of
a frame with a close-cut (no spacers) threadless fork of some value (how
good a fork, BTW? Deal of the day seems to be a lightly used Easton EC50
going for $3.24 on eBay with 3 days left...) which, for whatever reason,
they want an 8" rise on.

How on earth did the poor rider get into that situation in the first
place? Threadless or no, if the first step to properly sizing a bike is
an 8" riser stem, you should not be the owner of that bike. I don't care
if this is the bike you were racing until you slipped a disc and that's
your excuse: I own a bike with a close-cut steerer that fits me well for
racing, and the difference between my very low boy-racer position and
the wildest fantasies of Grant "Rivendell" Pedersen is a short stem with
4" of rise. Seriously. With that on the bike, it would be comfy for my
similarly-dimensioned but non-racing father.

Jasper: have you ever seen a rider on a conventional road or MTB frame
actually using an 8" riser stem, threaded or threadless? What was their
excuse?

Of the many differently-sized regulars on this newsgroup, the only one I
can imagine who would have call for an 8" stem, even in the worst
compact-frame-in-three-sizes circumstances, would be 6'lotsa" Chalo, and
he would probably break an 8" threaded stem. He is a great breaker of
parts and a fan of threadless stems, you know...

At some point, the frame doesn't actually fit,

--
Ryan Cousineau http://www.wiredcola.com/
"I don't want kids who are thinking about going into mathematics
to think that they have to take drugs to succeed." -Paul Erdos

Per Booker C. Bense:
There are worse things, but either a very short or very long
stem will make the bike handling "different".

I have a custom hard tail that I specified an extra-long top tube on - expecting
it to help keep the front wheel down.

It did, but my FS - which has an effective top tube over an inch shorter - is
even better in that respect.
--
PeteCresswell