ShimmerFade

So, I was comparing the geometry of my new Jamis with that of a Surly LHT (known as being a favorite commuter around here). Anyways, the Jamis has a 20.5 in (52cm) frame with a 19.21 in (48.8cm) BB to TT. However, the chainstay, TT length, HT/ST angles, and wheelbase geometry of this size of Jamis matches up almost perfectly with the 22.8 in (58cm) Surly LHT. The stand over height is the same as the 56cm Surly LHT at a little more than 32 in (81.5cm) with the 58cm Surly LHT at 83cm.

To compare the differences:

The Surly LHT has a 22.8 in (58cm) frame with a BB to TT of 22.8 in (58cm).

The Jamis Commuter 4.0 has a 20.5 in (52cm) frame with a BB to TT of 19.21 in (48.8cm).

Most other geometry measurements are extremely similar (which are perfect for what I am looking for in a commuter relative to my body proportions). The Jamis has a sloping TT which may have something to do with the differences, but I feel like differences in BB to TT of 3.59 in and 2.3 in in frame size are quite large. I am trying to figure out what the significance is of these differences.

Does it simply mean that I will need to put my seat up higher on the Jamis, or does frame size/BB to TT mean anything more important when all other geometrical measurements fit very well?

I hope this isn't too complicated, but I just don't know enough about bikes to come to a conclusion. Just say if more information is necessary.

Edit: Oh yea the reason I am concerned is that the bike was bought in the US, and I am out of the country until August (too late to return the bike). My parents say it looks like the perfect size for me, but they don't know a ton about bikes.

astroman

i might be wrong, but it might be because the lht has a very low, touring style, bottom bracket, hence the difference in bb-tt. just a thought...