Correct Top Tube vs. Correct Frame Size

I would say the LBS is mostly correct. The most important part of the
fit is your leg extension and knee position. As long as your seatpost
extends high enough for proper leg extension and your saddle position
and arm reach places your knee plumb with the pedal axle at 3 & 9
position you should be alright. If your stretched out reaching for the
bars your going to have back problems. If you are sitting too far
foward and your knee is forward of your pedal then your going to have
serious knee problems. My suggestion is to fit the bike to your torso
and legs first, then adjust for reach. If you don't trust your LBS go
to a different shop or google "bike fit".

Good luck.

-Michael

RP10128 said:

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?

No, a short stem makes for a bike that doesn't handle as well as it should.
The primary measurement for a bike *is* the top tube. A taller seat post can
make up for the frame size otherwise. Also, as you get more fit and in
better condition, you will have a tendency to want to get *longer*, that is
be more stretched out.

How did you arrive at the 50.5 dimension for the top tube?

"Dave Thompson" <[email hidden]> wrote in
news:[email hidden]:

Quoted message said:

RP10128 said:

I need a bike with a top tube of about 50.5 cm. To get a top tube

of

Quoted message said:

Quoted message said:

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

Quoted message said:

Quoted message said:

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

Quoted message said:

Quoted message said:

frame and install a very short stem?

No, a short stem makes for a bike that doesn't handle as well as it
should. The primary measurement for a bike *is* the top tube. A

taller

Quoted message said:

seat post can make up for the frame size otherwise. Also, as you

get

Quoted message said:

more fit and in better condition, you will have a tendency to want

to

Quoted message said:

get *longer*, that is be more stretched out.

How did you arrive at the 50.5 dimension for the top tube?

In two ways. First, I have been riding my current bike (a 52 cm.
Trek) with the saddle slid all the way forward, and with the nut that
secures the seat post clamp slid all the way forward. With the
saddle in that position, the distance from the mid point of the
saddle to the center of the head tube is about 50 cm. Second, I feel
that the top tube of my current bike (which has a top tube of 52.3
cm.) is about 2 cm. too long.

"tntcoach" <[email hidden]> wrote in
news:[email hidden]:

Quoted message said:

I would say the LBS is mostly correct. The most important part of

the

Quoted message said:

fit is your leg extension and knee position. As long as your

seatpost

Quoted message said:

extends high enough for proper leg extension and your saddle

position

Quoted message said:

and arm reach places your knee plumb with the pedal axle at 3 & 9
position you should be alright. If your stretched out reaching for
the bars your going to have back problems. If you are sitting too

far

Quoted message said:

foward and your knee is forward of your pedal then your going to

have

Quoted message said:

serious knee problems. My suggestion is to fit the bike to your

torso

Quoted message said:

and legs first, then adjust for reach. If you don't trust your LBS

go

Quoted message said:

to a different shop or google "bike fit".

Good luck.

-Michael

You suggest that I fit the bike to my torso and legs first, and then
adjust for reach. But do you mean that I should get the smaller
frame with the shorter top tube, or buy the larger frame and then
install a very short stem?

RP10128 said:

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?

Where it comes to fit, the only thing that matters is the relative
position of three points...

1) Saddle
2) Crank
3) Bars

Now obviously, it's possible to get the above items right without
having a bike that's a joy to ride (think "really, really long stem"😉.

In your case, if you can get the three "fit points" right with a stem
that's no longer than 10-11cm at the most, INCLUDING getting the bar
HEIGHT right, then you should be pretty good to go. The only real
down side to riding a "shorter" (vertically) frame is that the bar
height RANGE is lower. If you don't need the bars up around the level
of the seat and/or can live with lots o' spacers and/or a stem with
considerable rise, the "shorter" frame should work.

A tool to help you work out the stem issue:

http://www.habcycles.com/fitting.html

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

RP10128 <[email hidden]> wrote in news:Xns96A0D45BAB0C5richardpu2aolcom@
216.196.97.131:

Quoted message said:

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.

Top tube is more important, but if your seattube is too small then (depending
on frame geometry), your head tube may be very low. If you want your
handlebars several inches below saddle height, that may not be a problem. If
you want a more upright riding position, then you may have fit or handling
issues.

RP10128 said:

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?

Mark Hickey had some good advice above, but I just wanted to add that
seat tube angle can also vary between frames, and it's good to consider
this in addition to the top tube length. A 50.5cm top tube on a frame
with a 74 degree ST angle is not quite the same as one with a 73 degree
ST angle. If you put your seat in the same position relative to the
bottom bracket on both, then the reach to the bars will be about 1 cm
longer on the 74 degree frame (since you will need to slide the seat
farther back on the rails to get it in the same position).

Anyway, it's a very good idea to get properly fitted... there are lots
of online calculators and articles, and/or you could get it done at a
shop.

I just noticed that the price of a Habanero went up $100! Hasn't it
been $695 since the beginning? Maybe the recent currency value changes
in China had something to do with this...

-Ron

"RP10128" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

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?

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

"RP10128" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

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?

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

RP10128 said:

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?

Problem with a too small frame is the head tube is short and then the
hbars will be very low. To raise to a ridable height, need a lots of
rise stem or lots of spacers under the stem or something.

Frames from different makers are all different. perhaps a custom?

http://www.waterfordbikes.com

RS-14 series is only custom, made to order.

RP10128 said:

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?

Problem with a too small frame is the head tube is short and then the
hbars will be very low. To raise to a ridable height, need a lots of
rise stem or lots of spacers under the stem or something.

Frames from different makers are all different. perhaps a custom?

http://www.waterfordbikes.com

RS-14 series is only custom, made to order.

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.

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.

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.

In article <[email hidden]>,

Pete said:

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, [email hidden] (Drew

Eckhardt) said:

In article <[email hidden]>,

Pete said:

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

27 Jul 2005 19:52:31 -0500 RP10128 said:

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 [email hidden]
Madison, WI 53711 USA
-----------------------------------------------

In article <[email hidden]>,

Jasper Janssen said:

On Fri, 29 Jul 2005 10:25:29 -0600, [email hidden] (Drew

Eckhardt) said:

In article <[email hidden]>,

Pete said:

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.cfm?PageID=49&SKU=SM2344

That's...different.

This one's kinky:

http://harriscyclery.net/site/page.cfm?PageID=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 [email hidden] 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

Ryan Cousineau said:

In article <[email hidden]>,
Jasper Janssen <[email hidden]> wrote:

Quoted message said:

Quoted message said:

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.

Quoted message said:

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