How important is that one centimeter?

[slowandsteady]

So this "inquiry" is prompted by an ad in the Classifieds and one I see fairly often...How important is that one centimeter?

I see people trading or selling beloved frames (or even whole bikes) to move up or down just 1cm in frame size. Is this really necessary for a better fit?
Don't you think you can achieve the same results 99% of the time by adjusting your components like stem, saddle and seatpost? Is that 1 cm longer TT going to be THAT different for you that you need a new frame?

I understand that we are a Forum of bike snobs (I say that endearingly mind you) and we like perfection...but honestly, don't you believe that 99% of the time if we fiddle with the stem length and height or the saddle height and setback we can effect the same change as selling our frames to go ONE centimeter up or down? Heck, maybe even two cm's!

[ergott]

Thread title sounds like and ad for something else :p

[Gothard]

In my case, 1 cm in top tube length, all other things being equal made all the difference in descending stability.

[tsarpepe]

You are asking a very diverse crowd here. For many, the 1cm will make a big difference. They will tell you that a 57tt with 120mm stem rides differently from 58tt with 110mm stem. And they'll be right. For 99% of riders out there, however, this question is academic. They will not feel the difference in steering between those two combinations of TT/stem.

[charliedid]

With all due respect to everyone here and your question, sometimes people (we) need just that little justification to buy something new.

I'm sure some can defend it with good reason and who am I to doubt them. Some days I feel like I wish my frame was a little bigger some days a little smaller. Depends how much I have stretched that week, what I ate and drank etc.

55 to a 56 nah. 55 to 58 I would buy a new frame.

Some people just really love the "process" and so be it.

[Uncle Jam's Army]

The answer to the question, for me at least, depends on several factors. For example, a 73 degree seat tube angle with a 58 cm top tube would require me to run a 105 cm stem with my saddle slammed all the way back on a 25mm setback seatpost. However, a 72 degree seat tube with a 58 top tube would let me run a 120mm stem and have the rails centered on a 25mm setback post. I could feel the difference, as I feel much more balanced on this latter bike. Also, if the saddle/bar drop on a new frame would be 1 cm shorter or longer (and you couldn't adjust it with spacers or removing spacers), that would make a big difference in fit to me. YMMV.

[witcombusa]

How important is that one centimeter?

For me, not at all. My 60's and early 70's bikes are fit "in the style of the day" so they are 62 or 63cm ST's. Some of my 80's stuff is quazie race sized and are 58 or 59cm bikes. These days 61cm is about my sweet spot but plus or minus one matter little to me. As was already said, angles, TT length and even BB drop or CS length can all effect the feel.

So ST length is just the tip of the iceberg. (don't care one bit about standover height for a road frame either)

YMMV

[rugbysecondrow]

Size matters...

thats what she said.

[bobswire]

If I'm buying a custom bike that 1cm makes a huge difference (in my mind) but if I'm buying a used quality frame I can ride comfortably between 54-57 TT. Go figure? :rolleyes:

[lhuerta]

The answer to the question, for me at least, depends on several factors. For example, a 73 degree seat tube angle with a 58 cm top tube would require me to run a 105 cm stem with my saddle slammed all the way back on a 25mm setback seatpost. However, a 72 degree seat tube with a 58 top tube would let me run a 120mm stem and have the rails centered on a 25mm setback post. I could feel the difference, as I feel much more balanced on this latter bike. Also, if the saddle/bar drop on a new frame would be 1 cm shorter or longer (and you couldn't adjust it with spacers or removing spacers), that would make a big difference in fit to me. YMMV.


+1 !!

[Grant McLean]

I would say it depends on which 1 cm it is...

Most people are comfortable within a range of their fit,
and their preference for component set up is a combination
of factors, it's not an exact thing.

So if someone's personal "ideal" bike is a bullseye target
with a point in the centre, the distance you move away from the
middle is fine until you reach that point where you're outside
the ideal zone. That's how I look at it.

So where does that final 1 cm actually fall?

-g

[rain dogs]

In reality, 1 cm isn't a big difference. For me, the question is:

Which bike is this?

Is it a "dream" bike... is it your "prized" ride?

Or is it the daily commuter/slap-it-against-a-post and lock it?

If it's the latter then go for it. The former.... get it exact, otherwise you'll be looking to buy the same frame in 6 months wishing you could have it in the right size.

Don't buy a bike that immediately makes you want to buy it again in the proper size. Just don't.

[DRZRM]

I think the reason people are picking up used frames all the time is not to find the perfect size, but instead to try out the "dream" frame. I can make anything from a 58-61 top tube work, both of my road bikes have a 59. But only once have I sold a frame to replace it with the same frame in a larger size. Seems like everyone I knew was riding smaller frames in NYC the early 90s and I thought I belonged on a 57 (I may have even once owned a 56 Pinerello SLX with a 140 stem). Eventually I realized that I can't really make a 57 Legend work, so I essentially swapped it out for a 59. But generally, if a frame is in my size window, I figure I can replicate my contacts with setback and or stem adjustments.

[Ken Robb]

One way I can see that 1cm might matter is when the present bike is already a marginal fit and there is no way to get more comfortable by fiddling with stems, etc. any more.

[Aaron O]

I'm clearly in the 99%...if I adjust my post and stem a CM, I'll call it a day and not notice a heck of a lot of difference. To my surprise, I am finding that 2cm makes a notable (but usually acceptable) difference, and anything over 2cm is unacceptable.

I rode 53/54cm bikes when I was young and continued riding that size...I ordered a custom and was told by my builder that with my foot size, age and weight, I'd be better off on a 56 cm. I thought that seemed huge. We negotiated it to 55cm and I was skeptical. The sneaky bugger built it at 56 anyway. When i first saw the frame I thought...wow...that's big! Too big! I used a short stem (90cm) to compensate.

He was right...it's more comfortable for me, it's more stable for me and I've skewed larger ever since. I'm going to change the stem out to 100cm soon because it truly is neutral at 56cm. My 53cm bikes are all gone...the 54s are being phased out and 55-56 seems just right.

[ultraman6970]

IMO it depends, The geometry of the bikes plays a lot in the game if the frame is 1 cm shorter. Specially the seat tube angle because the reach of the bike will change. The other thing is that adjust 1 cm of difference is easier than try to fix a frame that is 2 cm or more cm shorter or larger. There are limits on what you can do, riding style have some influence too.

[azrider]

Too many factors in play IMO to make blanket statement does 1cm make that big a difference. Riding style, geometry, beater or race bike, st angle, etc.

I also think that if someone has gotten to the point where they are looking for a trade or to sell their bike they've probably already tried throwing a cm longer stem or adding a bit more setback. :rolleyes:

[mister]

like grant said it depends on where the 1cm is

the 1cm could probably be made to work with the fit
but sometimes that 1cm can change where the wheels are
that can make a large difference with the ride/feel of the bike

[MadRocketSci]

innuendo aside, i don't like 1cm too big...1 cm too small, much easier to deal with....

[charliedid]

All good points here.

if it is only the 1 cm TT and all other things being equal I would suggest it is a rare instance that this makes a discernable difference. If you go up one cm in TT and HT goes up slightly it could. Now if it means going from a 9cm to a 10 cm that could change the handling characteristics for someone who rides quite a bit and is tuned into the fit.

Am I square in my thinking here?

[mister]

All good points here.

if it is only the 1 cm TT and all other things being equal I would suggest it is a rare instance that this makes a discernable difference. If you go up one cm in TT and HT goes up slightly it could. Now if it means going from a 9cm to a 10 cm that could change the handling characteristics for someone who rides quite a bit and is tuned into the fit.

Am I square in my thinking here?

1cm in the tt all else being equal will make the front center 1cm longer or shorter
pretty sure most of us would know something was different

so many factors at play
everything relates to everything
there is no changing just one thing

[John H.]

1cm can make a lot of difference. I had a hip surgery about 7 months ago- post surgery, my saddle height went up by 1.6cm. I was all jammed up in the hip and not getting full hip extension.
This rendered my custom rain bike too small- It was built and set up to work with my saddle to bar drop and reach at 72.3cm saddle height- did not work very well at 73.9 saddle height- I could only raise the bars another 2mm.

[charliedid]

1cm in the tt all else being equal will make the front center 1cm longer
pretty sure most of us would know something was different

so many factors at play
everything relates to everything
there is no changing just one thing

Right, but if I follow the original question...I go 1 cm longer TT and swap my 110 stem for a 100. That seems like a reasonable fit/fix vs keeping everything the same and just buying a frame that is 1cm longer which is a much larger undertaking when a stem could do it. Or does that stem swap make a huge difference to you in terms of how the bike handles?

Me, not so much.

Follow me?

[jvp]

Off the shelf compact frames come in fewer sizes, leaving the size tweaking to stem length and saddle position. Not the type of bike the OP was refering to, but it seems to work for the many riders that can live with owning a sloping top tube bike:rolleyes:

[witcombusa]

Off the shelf compact frames come in fewer sizes, leaving the size tweaking to stem length and saddle position. Not the type of bike the OP was refering to, but it seems to work for the many riders that can live with owning a sloping top tube bike:rolleyes:

You mean that some people "like" them? :eek:

[tiretrax]

Size matters...

thats what she said.
According to some ads I hear on the radio, it's girth, not length.

I can definitely feel it on a compact frame, but not conventional geometry.

[bambam]

I would air on the side of my size or a cm bigger.
This is just me and it is because I usually have the seats all the way back with set back seatpost. I use the KOPS method of fitting and getting that knee to far forward concerns me. This may be irrational with the way people are set forward on Tri bikes but it is what it is. Frames sometime change the seat tube angle between sizes and a steeper angle means further forward saddle and I just don't want to buy if I'm mot sure it will fit. Right or wrong, I'm not sure.

[Chance]

In my case, 1 cm in top tube length, all other things being equal made all the difference in descending stability.
How did you go about keeping everything else equal on what sounds like a different bike? :confused:

[CNY rider]

I'm itching to buy the Hampsten Giro in the classifieds.
ST and TT are perfect.
But it's missing at least 1 cm, and preferably 2 cm, off the head tube that I need.
So I am going to pass, very reluctantly.

PS If you ride the same size bike as me (53/54) and like some saddle to bar drop, you need to buy that thing ASAP. It is hawt!

[jischr]

I guess its just me but I'm all over the bike on a typical ride. My butts back and hands on the drops descending; hand on the drops and butt on the nose on a sit down 'sprint'; and butt back and hands on the tops climbing; butt on the nose when I'm on my century bars; etc. A cm is nothing.

About the only thing in the same place all the time are my feet. I've never had a bike 'fit' partly because if they told me my favorite one didn't fit I ride it anyway because its fun to ride. For me fun is the bottom line. Don't even get me started on mm seat adjustments. :D

[Grant McLean]

Right, but if I follow the original question...I go 1 cm longer TT and swap my 110 stem for a 100. That seems like a reasonable fit/fix vs keeping everything the same and just buying a frame that is 1cm longer which is a much larger undertaking when a stem could do it. Or does that stem swap make a huge difference to you in terms of how the bike handles?

Me, not so much.

Follow me?

I was thinking more along the lines of you're already at a 10 cm stem,
and you need to go down a cm. Would you go to 9? It's about the
straw the breaks the camels back, as it were.

-g

[happycampyer]

Grant's point about the bullseye is dead on (no pun intended). And as others have mentioned, the dimensions often do not change in isolation, especially in a range of stock sizes. Over the years, I've owned dozens of bikes with 55 - 56cm-ish top tubes, which is a pretty narrow range. Even though most if not all could be made to work, differences were noticeable. An example was my old Moots Compact SL—I liked the way the 55 handled, but the head tube was a little short so I sold it and got a 56. The drop was better, but the handling wasn't quite as good. Once I arrived at a "Goldilocks" moment with a bike where everything is in the right place, I would hop on others and it would feel like i was steering a barge. At that point it was easy to unload a bunch of bikes and become much more selective about adding new ones.

[Chance]

I was thinking more along the lines of you're already at a 10 cm stem,
and you need to go down a cm. Would you go to 9? It's about the
straw the breaks the camels back, as it were.

-g
That’s an excellent question. But first we’d have to know what optimum stem length is. And we rarely see definitive opinions expressed in that area. Particularly from builders which seem to be purposely vague.

For me a range of plus or minus one centimeter from "ideal" seems very acceptable. And if for no other reason than aesthetics a bike’s ideal stem length should be in proportion to its size. Obviously function is more important but it seems to work out about the same for most riders anyway. Bottom line is that a 13 cm stem on a tiny bike looks as silly as a 10 cm on a huge bike. In the context of the OP my personal preferences:

For very small bikes 10 cm seems about right. So a range of 9 to 11 would be quite workable.

For medium size bikes 11 cm is a good target. Therefore anything between 10 and 12 is fine.

For large bikes 12 cm is more proportional. Any stem length between 11 and 13 is acceptable.

As others have implied, without some logical limits on stem length it would be possible to make almost any frame fit. If we can buy stems from 5 cm to 14 cm with ease then top tube lengths could vary by as much as 9 cm, and that’s just not proper and ridiculous to consider. So to answer the “last straw” question we first need to know what is the appropriate load rating for a camel. Even a rough guess of average is helpful.

Any opinions on what lengths fall in the right range?

[witcombusa]

The answer is whatever works for the owner of the bike.

Current "style" does not have to enter into it but often does.