Stem Length

jorge said:

I normally ride a 56cm bike.. I was recently involved in a crash that bent
my frame. I have the opportunity to buy virtually the same frame, except
in size 54cm (It is a good deal). I have taken all of the measurements
from my bike (relative to the BB), and determined that the 54cm bike can
be adjusted so that the seat and handlebars are in exactly the same
position as on my 56cm bike. The only major difference being that I would
need to increase the length of my stem from 100mm to 120mm. I am
wondering if this difference is stem length will substantially change the
feel or handling characteristics of the bike, for the better or for the
worse? Are there any other cons to moving to a smaller frame that I am
not aware of? Are there any other pros that I not aware of?

We can't really make this determination. In general, a "bargain" bike
that does not fit is no bargain. But, who knows, maybe the 56 was too
large for you. If the stem is any guide, and it really isn't all that
good, 100mm is on the short side, and 120mm is long (for a 54), but not
that unusual.

How much seatpost is showing on the old bike? You don't want it to look
like a compact frame with a 3-foot long seatpost (unless, I guess, it is a
compact frame, but that is another topic). If not enough post is inside
the frame, that would be bad. Where will your knee be in comparison to
what you are used to? Moving the seat up also moves it back; be sure to
take that into account.

--

David L. Johnson

__o | Become MicroSoft-free forever. Ask me how.
_`\(,_ |
(_)/ (_) |

the bike is not compact geometry, and the seat post goes into the frame well
past the "min insertion" line.

"David L. Johnson" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

jorge said:

I normally ride a 56cm bike.. I was recently involved in a crash that

bent

Quoted message said:

Quoted message said:

my frame. I have the opportunity to buy virtually the same frame,

except

Quoted message said:

Quoted message said:

in size 54cm (It is a good deal). I have taken all of the measurements
from my bike (relative to the BB), and determined that the 54cm bike can
be adjusted so that the seat and handlebars are in exactly the same
position as on my 56cm bike. The only major difference being that I

would

Quoted message said:

Quoted message said:

need to increase the length of my stem from 100mm to 120mm. I am
wondering if this difference is stem length will substantially change

the

Quoted message said:

Quoted message said:

feel or handling characteristics of the bike, for the better or for the
worse? Are there any other cons to moving to a smaller frame that I am
not aware of? Are there any other pros that I not aware of?

We can't really make this determination. In general, a "bargain" bike
that does not fit is no bargain. But, who knows, maybe the 56 was too
large for you. If the stem is any guide, and it really isn't all that
good, 100mm is on the short side, and 120mm is long (for a 54), but not
that unusual.

How much seatpost is showing on the old bike? You don't want it to look
like a compact frame with a 3-foot long seatpost (unless, I guess, it is a
compact frame, but that is another topic). If not enough post is inside
the frame, that would be bad. Where will your knee be in comparison to
what you are used to? Moving the seat up also moves it back; be sure to
take that into account.

--

David L. Johnson

__o | Become MicroSoft-free forever. Ask me how.
_`\(,_ |
(_)/ (_) |

-----BEGIN PGP SIGNED MESSAGE-----

In article said:

I normally ride a 56cm bike.. I was recently involved in a crash that bent
my frame. I have the opportunity to buy virtually the same frame, except in
size 54cm (It is a good deal). I have taken all of the measurements from my
bike (relative to the BB), and determined that the 54cm bike can be adjusted
so that the seat and handlebars are in exactly the same position as on my
56cm bike. The only major difference being that I would need to increase
the length of my stem from 100mm to 120mm.

_ That seems with reason and common practice.

See

http://www.hampsten.com/Company/design.html

for interesting comments on stem length/frame size.

_ There's a web page on the Park site about transfering
setup measurements from bike to bike. I would double
check that you can get all of these with the new bike
before purchase.

http://www.cyclingnews.com/tech/fix/?id=roadposition

Quoted message said:

I am wondering if this
difference is stem length will substantially change the feel or handling
characteristics of the bike, for the better or for the worse?

_ It will be different, but some people like it and some don't. A
lot depends on how far the stem extends above the top tube as
well. Really long quill stems like the Nitto can feel a bit
squirrelly at times. This is one place that Aheadset design
is superior if you use a steel steerer tube.

Quoted message said:

Are there any
other cons to moving to a smaller frame that I am not aware of? Are there
any other pros that I not aware of?

_ If the 54 and 56 are measured the same way ( ie c-c or c-t ),
then 2cm is not a killer IMHO. It really depends on a lot of
other dimensions that you haven't listed. Are the frame angles
different, has the wheel base changed significantly?

_ I regularly switch from a 52cm c-c bike to a 56cm c-t bike
and while they are definitely different, I would be hard pressed
to call one better than the other. Most of the differences
have to do with the rest of the geometry and not the 2.5 cm
on the seat tube.

_ Booker C. Bense

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jorge said:

I normally ride a 56cm bike.. I was recently involved in a crash that bent
my frame. I have the opportunity to buy virtually the same frame, except in
size 54cm (It is a good deal). I have taken all of the measurements from my
bike (relative to the BB), and determined that the 54cm bike can be adjusted
so that the seat and handlebars are in exactly the same position as on my
56cm bike. The only major difference being that I would need to increase
the length of my stem from 100mm to 120mm. I am wondering if this
difference is stem length will substantially change the feel or handling
characteristics of the bike, for the better or for the worse? Are there any
other cons to moving to a smaller frame that I am not aware of? Are there
any other pros that I not aware of? Thanks, Jeff

A 12cm stem is getting long for a 54cm frame. I think you'd be better
on the 56cm. The 54cm would be fine if the top tube was longer.

Booker C. Bense said:

-----BEGIN PGP SIGNED MESSAGE-----

In article said:

I normally ride a 56cm bike.. I was recently involved in a crash that bent
my frame. I have the opportunity to buy virtually the same frame, except in
size 54cm (It is a good deal). I have taken all of the measurements from my
bike (relative to the BB), and determined that the 54cm bike can be adjusted
so that the seat and handlebars are in exactly the same position as on my
56cm bike. The only major difference being that I would need to increase
the length of my stem from 100mm to 120mm.

---8<----cutting middle

Quoted message said:

_ It will be different, but some people like it and some don't. A
lot depends on how far the stem extends above the top tube as
well. Really long quill stems like the Nitto can feel a bit
squirrelly at times. This is one place that Aheadset design
is superior if you use a steel steerer tube.

------8<---cutting

Quoted message said:

_ If the 54 and 56 are measured the same way ( ie c-c or c-t ),
then 2cm is not a killer IMHO. It really depends on a lot of
other dimensions that you haven't listed. Are the frame angles
different, has the wheel base changed significantly?

_ I regularly switch from a 52cm c-c bike to a 56cm c-t bike
and while they are definitely different, I would be hard pressed
to call one better than the other. Most of the differences
have to do with the rest of the geometry and not the 2.5 cm
on the seat tube.

_ Booker C. Bense

I'll gladly second Booker's analysis. The seat tube length is not a big
deal. Now of course many builders will make a 54 frame a half degree
steeper (e.g. 74 in the case of Colnago) than a 56 (73,5), but that's
also small adjustments (of the order of 5 mm on the saddle rail, to get
the same effective setback relative to centre bracket). A slightly
bigger difference will be the loss of 1-2 cm on the top tube going to
the smaller frame, which can be offset fitwise by using the 120 stem as
you correctly point out. OK, that's not the complete story since you
will sit slightly more forward relative to the front wheel but it's
close enough.

I used to ride a 56 cm c-t but last year switched to a 52,5 cm frame
(Colnago call it a "54", but they measure from centre of centre bracket
up to seat post clamp, which is far beyond the top of top tube -
weird!). Now I have a proportionally shorter torso in relation to my
height, so the shorter top tube with a 120cm stem feels really good. I
also like the agility of the smaller frame with shorter wheelbase,
though I have to use a 4 cm stack of spacers between a-headset and the
stem. Just the same, the bar tops are a good 10 cm below the saddle tip.

But I love it and now wonder why I didn't try a smaller frame earlier on
in my biking life. It's kind of like having all the advantages of a nice
rigid compact frame without its ugly looks ;-)

/Robert

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

Quoted message said:

I normally ride a 56cm bike.. I was recently involved in a crash that bent
my frame. I have the opportunity to buy virtually the same frame, except in
size 54cm (It is a good deal). I have taken all of the measurements from my
bike (relative to the BB), and determined that the 54cm bike can be adjusted
so that the seat and handlebars are in exactly the same position as on my
56cm bike. The only major difference being that I would need to increase
the length of my stem from 100mm to 120mm. I am wondering if this
difference is stem length will substantially change the feel or handling
characteristics of the bike, for the better or for the worse? Are there any
other cons to moving to a smaller frame that I am not aware of? Are there
any other pros that I not aware of? Thanks, Jeff

It will feel significantly different when you stand up, as your weight
will be further over the front wheel. You may or may not prefer the
way it feels, so I can say if it's a pro or con.

You may also find that on the smaller frame you have trouble getting
the bars high enough, due to the shorter head tube on the smaller
frame. You'll likely either need a bunch of extra spacers, which may
lead to more flex in the steerer tube (again, which you may or may not
like) or you may have to use a stem turned over so that it angles
upward.

One last thing, while you're keeping the bars in the same place,
you're bringing the stem/steerer tube 2cm closer to the saddle, which
may lead to lot's of problems with you banging your knees on the stem
every time you stand up. Hard to see that one as a 'pro'.

The smaller frame is NOT a good deal, IF it doesn't fit. For what
it's worth, every time I've ever tried to get by on a frame that
wasn't right, it NEVER justified the savings.

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

Quoted message said:

I normally ride a 56cm bike.. I was recently involved in a crash that

bent

Quoted message said:

my frame. I have the opportunity to buy virtually the same frame, except

in

Quoted message said:

size 54cm (It is a good deal). I have taken all of the measurements from

my

Quoted message said:

bike (relative to the BB), and determined that the 54cm bike can be

adjusted

Quoted message said:

so that the seat and handlebars are in exactly the same position as on my
56cm bike. The only major difference being that I would need to increase
the length of my stem from 100mm to 120mm. I am wondering if this
difference is stem length will substantially change the feel or handling
characteristics of the bike, for the better or for the worse? Are there

any

Quoted message said:

other cons to moving to a smaller frame that I am not aware of? Are

there

Quoted message said:

any other pros that I not aware of? Thanks, Jeff

Unless the 56cm bike is on the small side already, I think you'll be fine
with a 54. The longer stem will slow down steering a little, but that's
usually the kind of thing you compensate for without thinking about it. I'm
6'10" and used to riding slightly small frames with big stems. My current
stem is 130, and that's on a touring frame with relatively sedate handling
already, I don't even think about it.

Quoted message said:

the bike is not compact geometry, and the seat post goes into the frame
well
past the "min insertion" line.

A bike can be a bad fit and still have the seatpost above the "min
insertion" line. The biggest issue going to a smaller frame is whether you
can get the stem high enough. But no matter what, if you had a 56cm that
you felt fit nicely, I wouldn't even consider going to a smaller size
without having the opportunity to ride it, properly set up, first.

I can guarantee you that, even if you set them up identically, they'll still
feel different. I can't tell you which will be better or worse, but
definitely different.

I will also say that, in general, people are more comfortable with frames
that are "too large" than those which are "too small", if the top tube/stem
distance remains the same.

A lot of this hinges on whether the 56cm was the right size to begin with.
If you feel that it is/was, then it's dumb to change. Or, let's look at it
this way. If money wasn't an issue, which size would you buy? That's the
way you should go.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com

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

Quoted message said:

I can guarantee you that, even if you set them up identically, they'll still
feel different. I can't tell you which will be better or worse, but
definitely different.

Could you please elaborate on this? Can you give some specifics
examples of what will feel different? Another poster mentioned how
the "longer stem on a smaller bike" will put the front wheel farther
back when standing and climbing. Can you give some similar examples?

I'm not trying to argue or criticize, I just want to understand this
subject better. (The subject being how two different size bikes feel
different if the points where the body contacts the bike are of
identical dimensions. This would mean identical distance from the
seatpost to handlebars, handlebar vrs seatpost height, bottom bracket
to seat distance and angle, etc).

Tom

Quoted message said:

Quoted message said:

I can guarantee you that, even if you set them up identically, they'll
still
feel different. I can't tell you which will be better or worse, but
definitely different.

Could you please elaborate on this? Can you give some specifics
examples of what will feel different? Another poster mentioned how
the "longer stem on a smaller bike" will put the front wheel farther
back when standing and climbing. Can you give some similar examples?

I'm not trying to argue or criticize, I just want to understand this
subject better. (The subject being how two different size bikes feel
different if the points where the body contacts the bike are of
identical dimensions. This would mean identical distance from the
seatpost to handlebars, handlebar vrs seatpost height, bottom bracket
to seat distance and angle, etc).

On the frame with a shorter top tube & longer stem, you're positioning
yourself differently over the front wheel than would be the case with a
longer top tube & shorter stem. I know this very well, as I raced two bikes
that couldn't be more different in terms of top-tube length. My Bob Jackson
was exceptionally short, while my Cinelli was quite long. Had a 12cm stem
on the Jackson, and an 8cm on the Cinelli. The contact points were
identical, but the feel of the two bikes quite different. I preferredthe
Cinelli, but could descend equally well on either bike. They had different
personalities, but not really different capabilities.

Of course, since these were two different-brand bikes, there are more
variables than just frame size involved; the main point of the illustration
was that I could adapt easily to either bike, yet I preferred one over the
other.

From a practical matter, we set up bikes with the same contact points but
different sizes all the time at the shop, as customers often question what
the next larger or smaller frame would be like. It's a very rare thing that
someone comes back without an opinion that they preferred one over the
others. You don't hear people saying "I can't tell the difference."

For what it's worth, I'm not a fan of "3 sizes fits everybody bike fitting,
just change the stem & seatpost."

--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
IMBA, BikesBelong, NBDA member

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

Quoted message said:

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

Quoted message said:

I can guarantee you that, even if you set them up identically, they'll
still
feel different. I can't tell you which will be better or worse, but
definitely different.

Could you please elaborate on this? Can you give some specifics
examples of what will feel different? Another poster mentioned how
the "longer stem on a smaller bike" will put the front wheel farther
back when standing and climbing. Can you give some similar examples?

I'm not trying to argue or criticize, I just want to understand this
subject better. (The subject being how two different size bikes feel
different if the points where the body contacts the bike are of
identical dimensions. This would mean identical distance from the
seatpost to handlebars, handlebar vrs seatpost height, bottom bracket
to seat distance and angle, etc).

Tom

"Mike Jacoubowsky/Chain Reaction Bicycles" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

Quoted message said:

Quoted message said:

I can guarantee you that, even if you set them up identically, they'll
still
feel different. I can't tell you which will be better or worse, but
definitely different.

Could you please elaborate on this? Can you give some specifics
........

On the frame with a shorter top tube & longer stem, you're positioning
yourself differently over the front wheel than would be the case with a
longer top tube & shorter stem. I know this very well, as I raced two bikes
that couldn't be more different in terms of top-tube length. My Bob Jackson
was exceptionally short, while my Cinelli was quite long. Had a 12cm stem
on the Jackson, and an 8cm on the Cinelli. The contact points were
identical, but the feel of the two bikes quite different. I preferredthe
Cinelli, but could descend equally well on either bike. They had different
personalities, but not really different capabilities.

Of course, since these were two different-brand bikes, there are more
variables than just frame size involved; the main point of the illustration
was that I could adapt easily to either bike, yet I preferred one over the
other.

From a practical matter, we set up bikes with the same contact points but
different sizes all the time at the shop, as customers often question what
the next larger or smaller frame would be like. It's a very rare thing that
someone comes back without an opinion that they preferred one over the
others. You don't hear people saying "I can't tell the difference."

Thank you for the thoughtful reply. I have a lot of road bikes, most
of them 20+ years old with longer wheelbases, more rake in the fork,
and (some) with larger, wider tires. I also have three newer frames.
There are obvious differences in the ride characteristics. This what
got me thinking about this subject.

Tom