I built an Audax frame a few years back and have been riding it ever since.
It is built with a Reynolds 631 main triangle (all .8 .5 .8) 28.6 TT and ST 31.2 DT and 31.7 HT with 725 seat stays and Columbus chain stays (cannot remember the specs of these) My weight is 168lbs and I am 6 foot tall
The bike is supremely comfortable and perfect for winter rides, Audax rides etc. It is a little flexy however and not ideal for fast club rides. I did take it touring once with just rear paniers and fast down hills were interesting
I am now planning to build another frame, again with 631 (or possibly 853) but want to make a pure road bike for faster club rides. So I would like it to be less flexy to improve handling whilst sacrificing as little comfort as possible. and of course, not adding too much weight.
My initial thoughts are below, your comments, advice and criticism would be appreciated.
1 I will be using an off the shelf carbon Fork (At the moment I am looking at the Columbus Minimal) 1 1/8 inch as there is a lot more choice and the larger HT will help handling.
2 I will stick with .8 .5 .8 tubes but use a 35 mm DT, to reduce flex.
3 ST and TT to be 28.3 to retain some comfort. Reynolds do a ST that tapers from 31.7 at the BB to 28.3 at the top - might consider this. The frame will be sloping top tube so I can use a relatively long 27.2 seatpost which I believe helps comfort.
4 631 or 853 ?? Reynolds have a minimum order so I could get 2 sets of 631 tubes or 1 set in 853. I believe they will both feel the same so am leaning toward the 631 with spare tubes for a second frame or in case of errors.
5 Seat stays and chain stays - not sure yet maybe lightweight seat stays and some beefier chain stays.
6 I have considered going fully oversize with 31.7 TT and ST I am not sure if this will make the bike too stiff, also, seat posts for this size seem to be few and far between.
7 Geometry. I am looking at 73 degree HT 72.5 seat tube. 57mm trail 75mm BB drop and 419mm chain stays
8 BB will be approx 260 to 265mm off the ground depending on tyres. Possibly lower as I dont race and am OK with a low BB
Does this all seem logical and practical ?