[pedalinbob]

18.5, 2018 Top Fuel was slightly large (felt a bit long). But the saddle was nicely centered on the seatpost, which has 25mm setback. This allowed the tip of the saddle to be 2.25" behind the center of the BB.
I'm 5'7.5", inseam a few mm less than 32".
I have fairly long femurs.

Per the literature, the 17.5 front end should be 16mm shorter, with an identical rear. Saddle should have been in the same position.

Yet, I have to push my saddle all the way back on the 25mm setback post. Even that far back, the saddle is only 2" behind BB. I think this is placing more weight on my hands, causing discomfort.

Mino is in low position. In high position, the saddle is ~9mm more forward.

A side note: what is the real seat tube angle on the Top Fuel? It is listed as 69.4 degrees for the 2018, but this makes no sense to me. I think it is 74 in low, 74.9 in high, same as the 2019 model

I'm stumped.

Bob

 

[LyNx]

Can't help you with why things seem to be lining up differently with the STA, once the post is at the same height on both sizes, it should also be at the same angle. What I have to ask, is why you went with the smaller frame instead of just getting the 18.5" and running a bit shorter stem than stock? ut: You do know you can change/replace stems, right? :skep:

 

[Shartist]

I dub thee, Goldilocks!

 

[pedalinbob]

Princess and the pea.

Despite a 50mm stem ( stock is 90 on the 18.5), I was still slightly stretched, and couldn't easily get behind the saddle on descents.
It also felt cumbersome in some of the tighter, twisty trails.
The bike just felt too long.

Bob

 

[chazpat]

Ditch the setback seat post if it's too long on the large. Sounds like you're a bit hung up on the numbers.

Or try some other bikes.

 

[newking]

Shorter stem. I'm probably the same size as you.

I just upgrated from a 2016 Top Fuel 9.8 17.5 size to a 2018 Top Fuel 9.9 RSL 18.5 size. The 18.5 felt slightly bigger so I changed from stock 80mm stem to a 40 and it fits great.

Never liked stems longer than 50-60mm anyways.

the 2018 TF 9.9 RSL with 120 stepcast is an AMAZING bike!!!

18.5, 2018 Top Fuel was slightly large (felt a bit long). But the saddle was nicely centered on the seatpost, which has 25mm setback. This allowed the tip of the saddle to be 2.25" behind the center of the BB.
I'm 5'7.5", inseam a few mm less than 32".
I have fairly long femurs.

Per the literature, the 17.5 front end should be 16mm shorter, with an identical rear. Saddle should have been in the same position.

Yet, I have to push my saddle all the way back on the 25mm setback post. Even that far back, the saddle is only 2" behind BB. I think this is placing more weight on my hands, causing discomfort.

Mino is in low position. In high position, the saddle is ~9mm more forward.

A side note: what is the real seat tube angle on the Top Fuel? It is listed as 69.4 degrees for the 2018, but this makes no sense to me. I think it is 74 in low, 74.9 in high, same as the 2019 model

http://i65.tinypic.com/2arxh3.jpg[/IMG

I'm stumped.

Bob[/QUOTE]

 

[pedalinbob]

The setback seatpost was required on both frames to attain proper pedaling position.

I'm definitely concerned about the numbers, because despite paying careful attention to them, I clearly ended up with a strange fit.

I posted this question hoping someone may notice something I've missed (I tried to post a pic but it didn't work).
In other words, instead of assuming omniscience, I assumed I made a mistake or missed something, and reached out for some collective wisdom.

I think I will contact Trek, because something is definitely off.

Bob

 

[LyNx]

As someone who can feel a few MM in saddle height difference, who adjusts saddle height depending on which shorts I'm wearing, I think you definitely take the award for biggest princess ;0

Think you have the size you want, but maybe not the actual bike to suit your riding preferences or you needed to try a 40mm stem and give the 18.5" more time to get accustomed to the handling.

I think people are just surprised about what you're "feeling" :skep: Absolutely hear you on the setback post to get in the proper position relative to the BB for you, I have to do the same with a STA steeper than 73*. Have absolutely no clue what could be going on in that you can't get the saddle to where you need it with the same setup, geo lists STA the same on all models, so at the same height, with the same post and saddle, it should fall the same place relative to the BB.

Have you actually taken a tape measure to the bike to see what measurements you come up with? Are you in fact on the same saddle as you demoed the 18.6" with? Same post brand?

Princess and the pea.

Despite a 50mm stem ( stock is 90 on the 18.5), I was still slightly stretched, and couldn't easily get behind the saddle on descents.
It also felt cumbersome in some of the tighter, twisty trails.
The bike just felt too long.

Bob

The setback seatpost was required on both frames to attain proper pedaling position.

I'm definitely concerned about the numbers, because despite paying careful attention to them, I clearly ended up with a strange fit.

I posted this question hoping someone may notice something I've missed (I tried to post a pic but it didn't work).
In other words, instead of assuming omniscience, I assumed I made a mistake or missed something, and reached out for some collective wisdom.

I think I will contact Trek, because something is definitely off.

Bob