Could she have a bad fit on a Trek Speed Concept - sure.
Could she have a mediocre fit on a Trek SC - prolly.
Could she find her best position on a this bike, cause that's what we want all athletes to have, the optimal position - unknowable on the internet.

There's really only two ways to know for sure:
1) She's already riding in the optimal position on an older bike that will be replaced by the Trek. If that's the case, get the Pad X, Pad Y off of that existing bike and we can compare it to the the SC prescriber.
2) Have her to got a fitter who is a) educated, b) experienced in pre-fitting for tri bike and c) has a dynamic fit bike and that fitter will spit out her Pad X, Pad Y and look compare it to the Trek's...and she'll also have her fit coordinates too (seat height, setback, cockpit, drop, etc).

If 1 is the method - I can help. If 2 is the method I can help. If you're going to forgo this process then it's not possible to answer your question because we don't know if the 5ft tall athlete is long in torso and short in leg and likes to ride long and low (so the Trek SC low-far stem would be installed) or if your athlete is long in leg, short in torso and needs the near-tall stem - or something in between our or outside of the Trek Speed Concept's range.

Ian

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Ian Murray
http://www.TriathlonTrainingSeries.com
I like the pursuit of mastery
Twitter - @TriCoachIan

Exactly. I wanted her to go to a specific fitter in our area who would fit her on a guru bike to get all measurements and then we could know exactly what would fit her. The fitter she went to used a fit bike but only gave her stack and reach and I am having a difficult time finding a fit with those numbers in the Speed Concept fit chart. The fit numbers that were given to her were reach 365 and stack 481. I did see a picture of her on the fit bike and this fit was super duper conservative. This is her first tri bike so nothing to compare it to. She only has a road bike right now. I appreciate your assistance!

This shouldn't be too hard.

Stack and Reach is 481 & 365. A good start.

Contact the fitter and tell 'em - "we're looking at a super bike, I need to know Pad Y (Pad Stack) and Pad X (Pad Reach) of her final position". The software that comes built into the Guru DFU preserves all the numbers and the hardware used during the fit so they will be able to zoom the bike back into the same position (albeit a conservative position). Ask them to put back on the SAME aerobar set-up that they used for her fit and measure from the center of the bar clamp to the top of the pad and then from the center of the bar clamp to the center of the pad (the center of the pad could be slightly behind the center of the clamp or in front we need to know that and by how much - in millimeters please).

Then, ask 'em to reach the HX HY right off the screen of their fit system.

I know this sounds confusing but we're talking about three X/Y coordinates that all exist in the same neighborhood:

1. Stack and Reach (used for mortal bikes, doesn't exist on the Guru Fit Bike)
2. HX/HY (this is what the Guru DFU tracks, remembers, and lives by)
3. Pad X, Pad Y (this is what we need to proceed in sizing the Trek Speed Concept and all other super bikes).

The fitter might already know how measure from HX/HY to get Pad X/Pad Y - if they don't you (or I, if you'd need me to) can walk them thru how to manually measure that, over the phone, in a matter of seconds.

Ian

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Ian Murray
http://www.TriathlonTrainingSeries.com
I like the pursuit of mastery
Twitter - @TriCoachIan

I talked with my athlete and she gave me the paperwork from the fitter and it has all the info we need.
Pad reach X - 425
Pad stack y - 610
Handlebar x - 425
Handlebar y - 555
Stem length - 80
Stem angle - -6
Stem stack - 40
Spaced height - 40
Head angle - 72.

With those numbers, to me, it looks like she would fit on an XS SC, right?
Thanks for the help!

another thing you might want to consider is her "future fit". This is the fit that she gets *after* the bad, ie. conservative fit she got before. In her future fit, done by and informed and competent fitter, she'll be in a much more orthodox time trial position and as such will most likely fit on an XS Speed Concept, in fact she'll *need* the extra reach, especially if they're telling her it will be too big now.

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Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

Thought the same exact thing after I saw her photo on the fit bike.

Give Dan Kennison a shout . I know he just produced an extra small. I believe he is dkennison on here.

https://www.premierbike.com/pages/bike-fit-guide

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Big Sexy Racing 2018

Seems like two different data sets, best to affirm the correct one first.

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"They know f_ck-all over at Slowtwitch"
- Lionel Sanders

The athlete would fit on our XS if those numbers are correct.

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Dan Kennison

facebook: @triPremierBike
http://www.PremierBike.com
http://www.PositionOneSports.com

He already messaged me but I am a big proponent of Trek and the Speed Concept.

As a follow-up to Eric's comment about maybe later wanting to be more aggressive ... I am about the same height; Ianpeace is my regular fitter for the last almost 15 years (Dan did a front-page article on my fit evolution last year).

I am surprised by how high that pad-Y number is -- my notes say mine is ~489 (saddle height 61), although I needed 650 wheels, undermounted bars, and a -27 stem to get there, and probably would have gone even a bit lower if I could have (even the fit bike can't get the front that low). When it is time for a new bike, I have no idea what I am going to do.

Fair enough ! Best of luck !

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Big Sexy Racing 2018

Can you refresh my memory and post a link to that article?

To everybody in general:

If the industry doesn't want to produce a 650C bike any more could they at least produce a 700C bike with a higher bottom bracket so the stack and pad Y is smaller? People can argue that handling won't be as good but as small as we are, the change in center of gravity won't make any difference.

The lowest 700C bikes have a stack of 480-500mm. If they brought that down to 450mm I could fit on a 700C bike.

Just for info...Trek hasn't made an XS in a Speed Concept for quite some time, so she'd have to go with a Small (700c), which can fit those coordinates, though I'm suspect of that fit.

Also keep in mind that if she's going lower, she'll need more reach. As it stands now, she's a bit in between the Med-Near and Med-Far stem, but I'm guessing, if she's relatively fit, that she could easily go lower, at which point a Low-Far would probably come into play.

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Jim Manton / ERO Sports

This caught my eye since my wife is 5'0" and she rides a XS gen 1 SC 7.0. I'd frankly be shocked if your rider doesn't fit on that bike.

Unfortunately, Trek no longer makes the XS. In the first gen they made it in both the 7 series (no integrated front end) and the 9 series. In the second gen they only made the XS in the 9 series for a while but now it's completely gone. I have saved on my hard drive the fit charts from both the first and second generation SC.

I compared your rider's numbers to my wife. Her stack looks a bit high and pad reach looks really long. Is the pad reach to the back of the armpad or middle? Either way a lot longer than my wife's numbers. Sorry to say, but I personally wouldn't trust that the fitter knows what he's doing.

At 5'0 ft, standover height will be an issue. I'm 5'4 and I can just barely clear most 48' frames. I started another thread last month asking for input on tri-bikes for shorter rides that was helpful.

Based on my research, Felt and QR are better geometries for shorter riders in general, but again every rider's flexibility/proportions are different.

https://www.slowtwitch.com/...on_Evolved_6318.html

I happened to be at Dan’s house during his flip-turn-lesson phase, and I had brought some underwater pictures. Somehow that led to my also showing him these, and then this article. I have newer pics now, but we haven’t changed the basic fit since then.

Pad stack of 610mm seems awfully high for an XS bike. Are you sure that's the correct number?

I ran a 610mm pad stack on an SC three sizes bigger.

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Favorite Gear: Dimond | Cadex | Desoto Sport | Hoka One One

we're dealing with a fitter who gave her a "kitchen table fit"....

ie. you sit down on a chair, lean forward onto your elbows, and eat dinner

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Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

This. My wife would be able to hit her pad coordinates on a Trek SC Small (with a low-far stem, slammed) - but she'd be sitting on the top tube dangling her feet at traffic lights. We're happy we went for the Felt.

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ZONE3 - We Last Longer