Hello all! As a recent re-discoverer of road cycling, I am hooked on this forum. I'm still riding a Diamondback Master GT that I've owned since ~'89/'90, and am considering an update to a newer steel frame with carbon fork. I also love the techie side of cycling, and over the years became pretty handy with bike mechanic stuff (even built my own wheels years ago). My plan is to buy a frame and fork and build up, using components from the Master, mixing in new (STI shifters, for example) where an obvious update is available. The Soma Smoothie has me pretty intrigued because it is unusual, is built with Reynolds 853 (main triangle) and seems a good compromise between being light but solid. They sell it on their site for $450/frame plus $180/IRD fork.

My questions have really to do with sizing. My DB Master TG is a conventional frame, with the following:

1) Seat tube C-T 56cm
2) TT C-C 56
3) standover height ~32" <<--not sure if I measured that correctly. Measured floor to top of TT with tires inflated--is that correct?
4) CS 41cm

This frame fit me very well, although I've had to be careful with stem length so as not to become too stretched out to the drops. BTW, I am 5'9", ~153#, and overall am trying to achieve a fit similar to the Master.

The Soma website states that the smoothie uses a "slightly" sloped TT, so I assume that means that their road frames use something of a "compact" design, and they give their geometries usign "actual" TT length and "level" TT length. Here's how they list out their Smoothie in the 54 size:

1) Seat tube C-T 54cm
2) TT "level" 56cm
3) standover height 30.6"
4) CS 40.5

OK, here's how I understand these numbers. The seat tube is going to be lower on a frame with a sloped TT, and the "level' TT measurement is right where my current bike is. The standover height is an inch and a half lower, but I assume that to be because of the sloped TT. I may be a dunderhead, but I am thinking about the sizing correctly? Any insight anyone can offer into sizing ideas and/or the quality of Soma frames for the price will be greatly appreciated! I emailed Soma on Sunday, waiting to hear back from them.

Thanks all!

Chris

All of them manufacturers use different reference points for seattube height and so on, but yea your in the ballpark as far as thinking is concerned, just reference everything using the bottom bracket as the reference, your not standing on the floor when riding after all and bbs seem to be getting higher for pedal cornering clearence-raise the bb means raise the seat and raise the bars too so in the end they are all in the same position relative to each other as when you started, many modern bikes have no standover or even a defecit(tiptoes) when properly fit because of this and many new bikes are misfit due to those that cling to the old standover standby fiting method.
try this link
https://www.sheldonbrown.com/kops.html
also try this one and click on
1. Ergobike: Competition Bicycle Size/ Proportions Analysis
It's a fitting program that lets you select the bike builder.
https://www.bsn.com/Cycling/