A question of fit

Triathlon Forum
1

Everyone around here harps on buy the bike that “fits”. So what is that really mean? Noone can really define for me what a bike that fits is.

So I have been toying with something and it brings this into question. Here is what I came up with…

http://farm4.static.flickr.com/3643/3351753502_58f2458ff2_b.jpg

The black triange is my current stem on my current frame.

The purple is the change in stack and reach from Dan’s charts to go to a SMALLER frame.

The red is the resultant stem on the smaller frame that would position me in the exact same point in space relative to the bb.

I have a couple of thoughts on this…

  1. the resultant stem is still within what I consider a good fit (<13cm)

  2. the resultant stem is “easier” to come by

  3. the smaller frame will move the steering axis farther back and the stem will have more leverage.

So, which stem/frame is a good “fit”? Are they both good fits? If not, which is the good fit and WHY?

g

2

proposed:

a bike that fits is any bike where the stem isn’t so long or short that handling gets weird

and the seat post isn’t so long that it adds undue lack of stiffness

Which, means just about any bike will likely carry a size that fits for normal heighted folks. imo

But, I may be missing some important factors.

3

agreed, but what defines where things get weird?

g

4

I’m not sure, I live in Houston so I wouldn’t notice anything weird even with a 20mm stem. No technical riding here!

As a reference point, my girlfriend is on a 55c frame.

The seat post is pretty high up, but the stem is really short and angled up (80mm 30 degree)

So thats probably starting to have some handling downsides, plus the aeroness of the frame is probably negatively impacted by the up leaning stem.

There will be no good way to resolve, as a smaller frame would lead to a ridiculous seat post and a larger frame would lead to a ridiculous stem.

So, a different brand of frame is probably in order some day.

agreed, but what defines where things get weird?

g

5

Everyone around here harps on buy the bike that “fits”. So what is that really mean? Noone can really define for me what a bike that fits is.

So I have been toying with something and it brings this into question. Here is what I came up with…

The black triange is my current stem on my current frame.

The purple is the change in stack and reach from Dan’s charts to go to a SMALLER frame.

The red is the resultant stem on the smaller frame that would position me in the exact same point in space relative to the bb.

I have a couple of thoughts on this…

  1. the resultant stem is still within what I consider a good fit (<13cm)

  2. the resultant stem is “easier” to come by

  3. the smaller frame will move the steering axis farther back and the stem will have more leverage.

So, which stem/frame is a good “fit”? Are they both good fits? If not, which is the good fit and WHY?

g
It’s hard without knowing how tall you are and what size frame you are looking at. I.e., if you were 4’11" then I’d want a different max stem length than if you are 5’11".

Generally, I’d say that 13cm is a rather long stem for a tribike. Because of the additional up front weight on the aerobars, I tend to advise a stem that is ~2cm shorter than the equivalent “correct” stem for a roadbike. So if 13cm is the longest road bike stem YOU would want, then 11cm is closer to the longest tribike stem you’d want.

However, the stem length is also dictated by the specific aerobars you use (unless you are going aero or die) as some bars with excessively long pursuit positions can make handling very tricky. The newest Ritchey base bar is an example of this as is the “down-and-forward” sweeping Vision one piece. On an aero-or-die position, this is obviously not a factor, but stem length is still important in terms of your weight distribution relative to the front axle.

It’s also dependent on the frame itself. On a bike with a lot of trail and/or front center (Cannondale Slice) a longer stem is less problematic than on a bike with less trail and/or front center (Orbea Ordu).

So it’s a hard question to answer just based on what you’ve written. My default reaction is to fit first to reach and then fit to height. If a bike is long enough, there are many ways to change the height (different aerobars, stem pitch, etc.). But only one way to change the length. However, the question I believe you are asking is what defines “long enough” and that’s impossible for me to answer given only what you wrote above.

6

Everyone around here harps on buy the bike that “fits”. So what is that really mean? Noone can really define for me what a bike that fits is.

So I have been toying with something and it brings this into question. Here is what I came up with…

The black triange is my current stem on my current frame.

The purple is the change in stack and reach from Dan’s charts to go to a SMALLER frame.

The red is the resultant stem on the smaller frame that would position me in the exact same point in space relative to the bb.

I have a couple of thoughts on this…

  1. the resultant stem is still within what I consider a good fit (<13cm)

  2. the resultant stem is “easier” to come by

  3. the smaller frame will move the steering axis farther back and the stem will have more leverage.

So, which stem/frame is a good “fit”? Are they both good fits? If not, which is the good fit and WHY?

g
It’s hard without knowing how tall you are and what size frame you are looking at. I.e., if you were 4’11" then I’d want a different max stem length than if you are 5’11".

Generally, I’d say that 13cm is a rather long stem for a tribike. Because of the additional up front weight on the aerobars, I tend to advise a stem that is ~2cm shorter than the equivalent “correct” stem for a roadbike. So if 13cm is the longest road bike stem YOU would want, then 11cm is closer to the longest tribike stem you’d want.

However, the stem length is also dictated by the specific aerobars you use (unless you are going aero or die) as some bars with excessively long pursuit positions can make handling very tricky. The newest Ritchey base bar is an example of this as is the “down-and-forward” sweeping Vision one piece. On an aero-or-die position, this is obviously not a factor, but stem length is still important in terms of your weight distribution relative to the front axle.

It’s also dependent on the frame itself. On a bike with a lot of trail and/or front center (Cannondale Slice) a longer stem is less problematic than on a bike with less trail and/or front center (Orbea Ordu).

So it’s a hard question to answer just based on what you’ve written. My default reaction is to fit first to reach and then fit to height. If a bike is long enough, there are many ways to change the height (different aerobars, stem pitch, etc.). But only one way to change the length. However, the question I believe you are asking is what defines “long enough” and that’s impossible for me to answer given only what you wrote above.
Uh, I believe that Greg’s questions were rhetorical in nature…

7 
   Uh, I believe that Greg's questions were rhetorical in nature...

Oh, c’mon…I don’t think it was a total troll…I’m thinking he really is trying to decide between 2 frame sizes… :wink:

8 
   Uh, I believe that Greg's questions were rhetorical in nature...

Oh, c’mon…I don’t think it was a total troll…I’m thinking he really is trying to decide between 2 frame sizes… :wink:

what gave you THAT idea? :wink:

That said, I appreciate Jordan’s reponse. And I agree that there isn’t enough info to decide just in the stem info, but maybe there is.

The point is that the aerobar setup is already defined and works just well enough on the existing size/stem. I am not starting from scratch.

My general question is not how should I be fit (I am more than happy with the fit), but weither one frame size is a better “fit” than the other.

And is it better to fit to the smaller frame or the larger (and why)?

Or is it sixes?

g

9

"And is it better to fit to the smaller frame or the larger (and why)? "

Well, a smaller frame will usually be stiffer (that’s generally considered a good thing but in a tri-specific bike maybe it’s not)
The smaller frame will be lighter
The smaller frame will have somewhat smaller surface area

However, this smaller frame will require a bigger drop from saddle to bars OR the addition of spacers or upward stem which re-increase surface area.

Assuming you have a way to get all of your touchpoints to the same location without getting ‘weird’, then the smaller one is generally the way people would go…but I don’t think it’s a compelling difference.

So when you hear people harp on the best bike being the one that fits, don’t get caught up in that implying any specific bike. Translate that in your head to something like this: “the best bike for you is the one that gets your TOUCHPOINTS in the correct place”. And as you point out, with proper selection of bars and stem, that can mean a lot of different bikes.

It could be a different story if you already have your snazzy $900 aerobars already chosen…and if they include an integrated stem. At this point your touchpoints are dictated SOLELY by your frame choice and you’ve got no room to deviate from the appropriate stack and reach.

10

i think i have some interesting input: just like most of you guys i’Ve always thought a smaler frame ist better because of weight, bar drop,…

But a friend of mine (an excellent masters track rider competing at int. level) told me he had talked to the owner of BT Bikes (http://www.biketechnologies.com/) who had mentioned he tries to seat his riders on the LARGEST frame possible in order to

  • increase front end stiffness that you would lose when using longer stems
  • get rid of those shallow steering angles smaller frames had (???)

he had also added that he used as much as 75° (!!!) of steering angle for his track frames (normally only sprinters’ bike sport angles THAT steep), and that he tries to mount the TT bars with the shortest stem available or even directly onto the fork (check out the bars on the BT homepage to see what i mean)

while some of his ideas might come from the UCI regulations (it’s easier to obey the “maximum reach of extension = front axle + 15 cm” rule), some might also be feasible for triathlon: when riding with very steep seat angles the center of gravity is radically shifted towards the front end of the bike, making cornering more difficult and resulting in a more unbalanced feeling than on a road bike. so i’d probably build my tri bikes with steep seat angles, long top tubes/reach, short steerer tubes/stack and very short stems. you’d get a longer wheel base for a more balanced weight distribution, more stable riding and also a stiffer bar area (which might be more important to road TTists). you could compensate the longer wheel base with a steeper steering angle

what do you guys think of this approach? Slowman? Any of the bike builders?

11

the bike kind of looks like a fuji and those handlebars are pretty sweet. Is the bike track only?

12

I’ll be at Pardyjak’s house next week - come by and we’ll give you the “correct” answer :wink:
.

13

yeah, they have a TT and a sprint frame, both for track racing only
.

14

That is funny - My wife forwarded me the SLC Running Co’s email with you guys in it…

g