Sizing advice

Spagoose

Hi, I have agonized for ages over what MTB to buy and finally settled on the 2019 X-Caliber 8, the only issue is that I'm now agonizing over what size to get.

I am 173cm/5'8 so I am just in the 18.5" sizing range but I wanted opinions on whether I should be sizing down or not.
I tried the 17.5" but not the 18.5" so I have no real way to compare them and none of the shops I can get to have a 18." in stock to try.

Looking at the geo, the stack is identical between the bikes, the only difference is the reach (416mm vs 432mm) and seat tube length (actually 16.5" vs 17.5" despite the labelled size).

My inseam is 31" and I have an arm span of 176cm.

Does anyone have any suggestions on what size I should go for? Am I better off going for the longer or shorter reach?

Killerclown

Spagoose wrote:

Hi, I have agonized for ages over what MTB to buy and finally settled on the 2019 X-Caliber 8, the only issue is that I'm now agonizing over what size to get.

I am 173cm/5'8 so I am just in the 18.5" sizing range but I wanted opinions on whether I should be sizing down or not.
I tried the 17.5" but not the 18.5" so I have no real way to compare them and none of the shops I can get to have a 18." in stock to try.

Looking at the geo, the stack is identical between the bikes, the only difference is the reach (416mm vs 432mm) and seat tube length (actually 16.5" vs 17.5" despite the labelled size).

My inseam is 31" and I have an arm span of 176cm.

Does anyone have any suggestions on what size I should go for? Am I better off going for the longer or shorter reach?

The general way of thinking is, if you’re between sizes, size down tends to result in a more responsive ride, size up, gives a more relaxed ride. I would get a proper bike fitting done, if it was me though.

steve_sordy

You posted a similar question earlier about the Bizango and the consensus was to go for the smaller size then (ie the 16" and not the 18"). I know they are different bikes and will almost certainly have different proportions, but why go for the Trek 18.5"? Did the 17.5" feel OK or not? If it did, buy it!

Spagoose

steve_sordy wrote:

You posted a similar question earlier about the Bizango and the consensus was to go for the smaller size then (ie the 16" and not the 18"). I know they are different bikes and will almost certainly have different proportions, but why go for the Trek 18.5"? Did the 17.5" feel OK or not? If it did, buy it!

The Bizango was a bit of a pain, the 18" was definitely too big and when I finally tried a 16" the reach was way too short unfortunately.

The reason I'm looking at the 18.5" is because that's not the true size, it is in fact a 17.5" seat tube and likewise the bike listed as 17.5" is actually 16.5" because they are virtual sizes rather than actual.

I guess the reason I'm asking this is because I have never really been able to tell if a bike fits other than height wise. Since both are the same stack anyway I am deciding purely on reach which I struggle to judge.

Seeing as I have a positive ape index that makes me think I should tend towards the higher end of what the recommended sizes are.

Plus there's the fact that between the two options, I'm under the impression that putting a shorter stem on a longer bike is better than than vice versa.

I am basically wondering of the two, which would be more likely to fit and have a better range of fit for me to learn what my preferential fit actually is.