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Bike Size vs Fit Measurements

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Bike Size vs Fit Measurements

Old 03-05-23, 09:31 AM
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Bike Size vs Fit Measurements

I've got two bikes a Salsa Fargo (XL) and a Kona Libra (L) and currently they are set up with the same:
Saddle, Saddle Height, Reach (Saddle nose to hoods), Saddle setback (BB-saddle nose, similar stems (but not the same) and Handle bar width.

But they still feel different with the Fargo being super comfortable and the Kona just not as comfortable. I have tweaked a bit but for the life of me I can't figure out why they feel different.
Any suggestions as to what I might be missing. I'm thinking I may have to sell the Kona and buy another Fargo but that seems a bit extreme.

Thanks
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Old 03-05-23, 05:54 PM
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Are you using the same saddle? Are you using the same handlebar? Generally speaking the nose of the saddle isn't the part you sit on, and handlebars come in all sorts of widths, shapes,and reach and drop dimensions. And depending on the shape, the location and orientation of the brake hoods can be different.
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Old 03-05-23, 07:34 PM
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Are you sure hard-to-transfer things like saddle drop and set back were measured exactly the same way? Are they the same hoods? Did you measure to confirm bar widths or rely the manufactures' specs? There are three ways bars are measured.

What is the comfort difference? Two bikes will steer and vibrate differently regardless of fit.
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Old 03-06-23, 08:22 AM
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oldbobcat, kontact;

The saddles are exactly the same (make and model)
My method of measuring the saddle setback was to stand a 48" ruler (kind used in carpentry) at the front edge of the bottom bracket and measure back to saddle nose. The ruler is thin enough to stand between the chain rings and frame.

The handlebars are very different (Salsa vs Kona) - I will need to doublecheck the measurements to verify I didn't screw up.

Kontact - right on as to vibration/feel. The steel frame on the Salsa vs aluminium Kona - Totally subjective but the Salsa seems to have a "softer" ride, but maybe that's more geometry vs frame composition.
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Old 03-06-23, 10:08 AM
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What year models? Sometimes the geometry spec's change for models of bike. Also Kona list CM sizes not S, M, L, XL for their English website here in the US.

The two bikes have a way different stack and reach. And the seat tube angle of the Kona is a degree slacker and head tube 2° steeper. So those and other things are going to make a difference and you won't ever get the same feeling. That's not to say you can't make them both equally comfortable. But you'll have to give up on the idea of having the same identical position.
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Old 03-06-23, 12:38 PM
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Originally Posted by Iride01
What year models? Sometimes the geometry spec's change for models of bike. Also Kona list CM sizes not S, M, L, XL for their English website here in the US.

The two bikes have a way different stack and reach. And the seat tube angle of the Kona is a degree slacker and head tube 2° steeper. So those and other things are going to make a difference and you won't ever get the same feeling. That's not to say you can't make them both equally comfortable. But you'll have to give up on the idea of having the same identical position.
The Salsa is 2019 and the Kona 2021. I figured that if I got the same "measurements" I would be good on both, but maybe it is a question of the geometry being somewhat different is contributing to the feel. Which kind of means that I'm going to put the Kona on the trainer and tweak a little. I don't want to touch the Salsa as it is nicely dialled in for those all day rides in the back country.

I bought the Kona so I wouldn't be without a bike during the pandemic when bike parts etc. were almost non-existent - its my spare gravel / bike packing bike.

Last edited by Vaughan51; 03-06-23 at 12:41 PM.
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Old 03-11-23, 09:36 PM
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I've said this before somewhere. A bike has three sets of contact points, pelvis, feet, and hands. Three points make a triangle. The feet move in a circle, but the center of the circle is the bottom bracket spindle. If the sides of the triangle aee the same, the angles are the same. Duplicating hand position is the easiest to screw up because handlebars come in different shapes and widths. You have to look at where the hands actually go in relation to the feet and pelvis, not an indirect indicator like stem length. You also have to look at the handlebar width and the way the hands grip or rest on the bar. Or maybe you just have to spend more time getting used to the other bike. Good luck.
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Old 03-13-23, 04:30 PM
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Originally Posted by oldbobcat
I've said this before somewhere. A bike has three sets of contact points, pelvis, feet, and hands. Three points make a triangle. The feet move in a circle, but the center of the circle is the bottom bracket spindle. If the sides of the triangle aee the same, the angles are the same. Duplicating hand position is the easiest to screw up because handlebars come in different shapes and widths. You have to look at where the hands actually go in relation to the feet and pelvis, not an indirect indicator like stem length. You also have to look at the handlebar width and the way the hands grip or rest on the bar. Or maybe you just have to spend more time getting used to the other bike. Good luck.
So just went through an interesting exercise. Firstly let me say that I can't believe how rusty my math-geometry is but we did brush it off. Using the seat tube angles, saddle height, manufacturers specifications on the bike reach, and then extending the centreline of the head tube to the hand placement on the hoods I got an approximate 15-20mm difference between the Salsa an Kona. The Kona being the longer measurement. Also realized (once looking at the seat tube angles) that different angles result in slightly different saddle heights so a person can't just say its "xx" inches for both bike because less angle means less height.

I can suck some of that length difference up by switching out the stems and going to a shorter stem on the Kona and probably moving the saddle a "smidge" forward. But who would have guessed. I know it's all just "millimetres" what surprises me is that a persons body can feel it still. What can I say fun times.

Thanks everyone for the discussion it helps in approaching the problem in different ways.
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Old 03-18-23, 07:24 AM
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One important geometry spec hasn't been mentioned yet: STACK. Do you have the geometry specs of both bikes and can you post them here?
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Old 03-19-23, 12:44 PM
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Originally Posted by Vaughan51
So just went through an interesting exercise. Firstly let me say that I can't believe how rusty my math-geometry is but we did brush it off. Using the seat tube angles, saddle height, manufacturers specifications on the bike reach, and then extending the centreline of the head tube to the hand placement on the hoods I got an approximate 15-20mm difference between the Salsa an Kona. The Kona being the longer measurement. Also realized (once looking at the seat tube angles) that different angles result in slightly different saddle heights so a person can't just say its "xx" inches for both bike because less angle means less height.

I can suck some of that length difference up by switching out the stems and going to a shorter stem on the Kona and probably moving the saddle a "smidge" forward. But who would have guessed. I know it's all just "millimetres" what surprises me is that a persons body can feel it still. What can I say fun times.

Thanks everyone for the discussion it helps in approaching the problem in different ways.
Going off what oldbobcat mentioned, instead of doing a bunch of calculation, try measuring BB to saddle nose, nose to hood, hood back to BB. You don't need angles to see if you get two similar triangles. If they are different, figure out why. If you know the saddles are in the same spot (height and setback), then it will be easy to use the vertices from the nose and BB to figure out how to move the hoods.

Your comment about seat tube angle - that's why we measure set back. If your set back is right and your saddle height is right it doesn't matter what STA you started with. But you can't change either without affecting the other. Back and down or forward and up.

So double check your saddle positions and then measure the other two parts of the triangle and report back.
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Old 03-20-23, 07:52 AM
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Another way to get some idea is to put the bikes side by side. Stand back and take a good look at your contact points on the bikes and compare. But if the BB is in a different position under the saddle of each bike then they will feel different even if bar drop, saddle drop, saddle distance to bars/hoods is the same.

But you probably won't see the few millimeters of distance the BB might be off between the two that will make you feel that difference.
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Old 03-21-23, 08:55 AM
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Originally Posted by Kontact
Going off what oldbobcat mentioned, instead of doing a bunch of calculation, try measuring BB to saddle nose, nose to hood, hood back to BB. You don't need angles to see if you get two similar triangles. If they are different, figure out why. If you know the saddles are in the same spot (height and setback), then it will be easy to use the vertices from the nose and BB to figure out how to move the hoods.

Your comment about seat tube angle - that's why we measure set back. If your set back is right and your saddle height is right it doesn't matter what STA you started with. But you can't change either without affecting the other. Back and down or forward and up.

So double check your saddle positions and then measure the other two parts of the triangle and report back.
So I did measure saddle setback and etc. and they were different - not sure if I did some tweaking and forgot to record it or what. But I took a straight edge and clamped it to the centre of the bottom bracket against the chainring, measured and adjusted the Kona. So now I've got the same saddle setback and nose of saddle to hoods measurements.

At this point I'm got the Kona in the trainer and will ride for a week or two and see how it feels.

Oh and the Stack and Reach for the Salsa and Kona are 690/409 and 660/394 respectively. The Stack to Reach ratio is 1.69 and 1.68 so proportionately they are identical in that respect.
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Old 03-22-23, 11:52 AM
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Are tires the same? Tire pressure?




if these are the bikes in question, (Salsa is one year off so may be different) why should one expect them to feel the same? Steel v Al and geometry differences.
Measure the front-center, looks to be a big difference with Salsa greater. But that should affect handling more than cockpit comfort. I could not find the BB drop for each, but that also affects handling characteristics over 'comfort'. 'Comfort' is too subjective a term for analysis, unfortunately.

edit: My suggestion would be to ride the uncomfortable bike for a month, then compare to the comfortable one. Body adaptations over time can be amazing when one's focus is on having fun rather than analysis.
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Old 03-22-23, 02:30 PM
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Originally Posted by Wildwood
edit: My suggestion would be to ride the uncomfortable bike for a month, then compare to the comfortable one. Body adaptations over time can be amazing when one's focus is on having fun rather than analysis.
Except that discomfort on the bike can make it not fun.
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Old 03-22-23, 03:29 PM
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Re: saddle nose to either handlebars or BB vertical - as mentioned above, saddle noses aren't very good reference points if you are comparing different model/brand saddles. I put a piece of tape halfway between the nose and the back. Still not "precise" but this is a better indication of where my hip joint is going to be. I measure saddle height to the same point on the saddle.

I see that you are using the same seats. That makes things easy. Still, using the mid-seat as a reference means that your measured heights and reaches change little as you rotate the seat to optimize butt comfort. And to seat height, I use the heel on the pedal spindle, the appropriate shoe and heel thickness and that magic point where I can either bend my knee or straighten it without lifting my heel off the pedal For that test, seat shape, tilt, setback, STA doesn't matter.
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Old 03-22-23, 03:41 PM
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I mis-spoke OP's words:
'the Fargo being super comfortable and the Kona just not as comfortable.'

if he rides leather saddles is the Kona saddle broken-in like the older one?
OP seems to have eliminated the cockpit components.
Geometry won't change. The bikes are different.

Did I miss (quite possibly) a better definition of 'comfort'? Upper body, lower body, back, neck?
Does stack to reach ratio being almost equal mean comfort? Or genuine size differences?

Are we talking handling differences?

The Kona is on the trainer, and that's a good place to analyze fit, removing so many road variables. Swap 'em once that's a plan.
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Old 03-23-23, 12:39 PM
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Originally Posted by Kontact
Going off what oldbobcat mentioned, instead of doing a bunch of calculation, try measuring BB to saddle nose, nose to hood, hood back to BB. You don't need angles to see if you get two similar triangles. If they are different, figure out why. If you know the saddles are in the same spot (height and setback), then it will be easy to use the vertices from the nose and BB to figure out how to move the hoods.
That's the idea. But I don't use the nose because that's not the part most riders sit on. Saddles come in different lengths and shapes. For instance, a Selle Italia Flite and a Fizik Arione are both long saddles, but the Fizik has that long v-shaped section in the back that hardly ever gets sat on. Then there are those new shorty saddles that apparently let you hang your junk over the nose. The widest part of the saddle at the butt end is a more direct indicator of where the pelvis sits.
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Old 03-23-23, 04:30 PM
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Originally Posted by oldbobcat
That's the idea. But I don't use the nose because that's not the part most riders sit on. Saddles come in different lengths and shapes. For instance, a Selle Italia Flite and a Fizik Arione are both long saddles, but the Fizik has that long v-shaped section in the back that hardly ever gets sat on. Then there are those new shorty saddles that apparently let you hang your junk over the nose. The widest part of the saddle at the butt end is a more direct indicator of where the pelvis sits.
Since its the same model saddle, the nose is easier to measure to.
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Old 03-27-23, 08:10 PM
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Originally Posted by 79pmooney
Re: saddle nose to either handlebars or BB vertical - as mentioned above, saddle noses aren't very good reference points if you are comparing different model/brand saddles. I put a piece of tape halfway between the nose and the back. Still not "precise" but this is a better indication of where my hip joint is going to be. I measure saddle height to the same point on the saddle.

I see that you are using the same seats. That makes things easy. Still, using the mid-seat as a reference means that your measured heights and reaches change little as you rotate the seat to optimize butt comfort. And to seat height, I use the heel on the pedal spindle, the appropriate shoe and heel thickness and that magic point where I can either bend my knee or straighten it without lifting my heel off the pedal For that test, seat shape, tilt, setback, STA doesn't matter.
I use the widest point of a saddle to estimate where my sit bones are when riding. The justification is totally undisciplined, however, but its focussed on what supports my weight, rather than a totally arbitrary geometrical point. After I get a bike set up to sit comfortably, that's where my sit bones end up.

The value of this is that I can use a measurement from that saddle point to the hand contact point on the Ergopower levers, to compare their functional reaches, and sometimes to match them with a change of stem or bar.

This idea also does not have the disadvantage of possibly varying locations of the saddle nose, to a small degree with traditional leather like Brooks or Ideale, but especially with a Selle AnAtomica, which can stretch surprisingly from its as new condition, to those who use the nose screw to set the saddle gap width per S-A instructions. Even some Brooks have this problem: Swallow noses (beaks?) can be very extended after years of use and adjustment.

As well, if a saddle is goin to stretch, it will stretch a lot more near the front rivets and screws than it will in the wide part of the saddle. This is because the width of the leather surface is a lot wider near the nose than it is near the sitbone support area near the cantle. But (warning, here's the math part) if you integrate the saddle stress across the saddle at the front versus the rear, the stress will be a lot higher where there is less leather. Hence the strain or elongation will be greater at the front.

There's no good reason for this to be objectively correct, but it seems to work for me.

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