tsduke

lol. I have a 720 multitrack. The top bar is right there on the 4 but I can flat foot.

cloemans

Looking at the specs, it shows that FX 4 is larger.

Check measures between FX 4 "M" and FX 3 "L" (Both 2019) in Trek site.
(Since I am new, I can't post links or screenshots)

FX 3 "L" only have larger Seat tube and Stand over. But the rest are almost same values.
In fact, the "Effective top tube" is bigger on FX 4 "M" ( .2 cm, but my point is related to the difference between ML sizes).
Also, FX 4 is available on XS,S,M,L,XL against FX 3 S,M,L,XL,2XL.

I know that if I go with FX 4 I will chose Medium and it will be Large if I select FX 3.

tsduke

cloamans - which measurement makes you want to drop to a M on the FX4? It seems to me both of the bikes measure so close in the same size that one could make adjustments either way to get fit close to the other. I'm a hari shorter and don't think I could drop to a M in either model.

cloemans

Hi tsduke,

I'm 1,80 mts (5 ' 10,86 "). I'm in the limit of M and start of L, so that means is most depends on how it feels each size to me. Being in the limit I think there is no wrong answers here.
My current bike is 18 " and I'm feel fine with it. It has an effective top tube of 57 cm, and that's the same the FX 4 M and FX 3 L has. That's why I think FX 4 M or FX 3 L would be fine (for me).
I'm just need to decide on which model I will take. FX 4 looks better bike but also cost 40 % more.

tsduke

That would be tough having to decide without any test rides or without seeing one model/size before purchase. The FX3 L - FX 4 M do compare fairly close in reach.

In all things I always seem right in the middle and have to accept being off in one area to be better in another. Shoes, shirts, pants I swear I'm always between sizes so why would bikes be any different.

tsduke

It would be even better if we could all take the bikes on a full ride. I wonder what models shops that rent tend to have.

tsduke

Heres my little chart I did. I didn't compare across sizes though.

cloemans

About sizes:
Regarding clothes, I'm 90 % M and 10 % small. This thing of been between two sizes it only happens to me with bikes =P
At least you guys in US have several models and sizes to choose. Here were I'm live, I can't test FX 3 since is not in store. I have tested FX 4 M and I think it was fine about the size.

Pretty good table you've posted.
Like I said, FX 4 M and FX 3 L are very close on it's measures.

Have you tested both models?
What size have you felt better?

tsduke

Yes, but not at the same location. I will do that this week when my local gets a 4 L in, but I’m 95% on the 4 without a side by side test. I’m 5’10” with longer torso and arms with 31-32 inseam. The top bar is slightly lower on the 4 but on either model I’m barely on the starting edge of a large as far as the standover goes, but I think I reach for upper butter is too cramped on mediums.

i can always play with seat adjustment and handlebar angle/height slightly if needed.

Reach wise the 3 L and 4 M are close but on height they differ more.