this is damn close to what i'll be aiming for...with the understanding that all this is theoretical, the finished bike may be off a bit, but better to design precisely and build imprecisely than to design imprecisely and build imprecisely. and yea i'll be trying to make it precise.
the area that needs work now is the front end/steering geometry...i don't have the headset in hand yet, so i need to find out its exact lower stack height before locking anything down and building a jig.
the top tube is a compromise between fit and toe clearance. this is one area where i found an enormous amount of conflicting info. Paterek claims front center determines toe overlap--that 58cm is the magic number over which it's not a problem. R. Sachs says not to worry about it--that fit is infinitely more important. a recent discussion on the framebuilders list went on for a week.
i tried to strike a balance between the two Rivendell models i'm copying, the Atlantis and Ramboulliet, and my TT length is about mid-way between the TT lengths of their 58cm sizes. ditto for the chainstays, which are shorter than i had originally planned, but should make the bike a little more maneuverable.
i'm going with a 71.5° HT, a half degree shallower than planned, to allow for a short TT and decent toe clearance. this stretches things out on the front end a bit, so the chainstays got shorter to make up for it in handling. hopefully the wheel flop will be OK. i kept trail 58-59 cm with a 30 mm tire by increasing fork rake 2 mm. the front end is by coincidence very close to the cannondale touring model, which i'm planning to test-ride before building.
i'll attach a drawing soon; it's stuck on my home computer with no WWW access.
in cm unless noted
this was all done in BG 5.1 by Martin Manning, so the info below will be most applicable to users of that program.
sternal notch 148.0
arm length (avg) 65.75
femur (thigh) length (avg) 52.2
foot length (avg) 26.35
saddle height, BBc-saddle top 73.64
virtual ST 58.7
virtual TT 57.0
HT angle 71.5°
ST angle 72°
CS length 44.4
BB drop 7.75
fork rake 5.2
@ 700x30 tire
front center 60.93
BBc height 26.35
trail 59.3 mm
standover, mid-TT 82.18
TT angle to horizontal 2.5°
TT c-c 56.26
DT c-c 63.12
HT length c-c 16.23
front brake reach 64.0 mm (designed for cantis, long calipers or centerpulls possible)
HT upper free length 20 mm
HT lower free length 6 mm
fork length on steerer axis 38.75
seat tube Deda ZeroUno 28.6 mm
down tube Deda ZeroUno 31.7 mm
top tube Deda ZeroUno 28.6 mm
head tube Deda ZeroUno 31.7 mm
steering column TT Verus 25.4 x 240 mm
chainstays Deda ZeroTre 29.9 x 16 mm single bend
seat stays Deda ZeroUno 16 mm
fork blades TT Verus 27.6 x 20 x 400, 1.1-0.6 mm
seat lug Long Shen 74° long pt
top head lug Long Shen 74° long pt
bottom head lug Long Shen 60° long pt
BB shell Long Shen 60.3° x 62.3° x 7.3° x 30x1
fork crown R. Sachs/Long Shen Newvex
top eyes/seatstay caps Silva 16 mm
rear dropouts Tecnociclo 70° 2-eyelet
front dropouts Long Shen stainless 2-eyelet plug-in
chainhanger Columbine Quikchainger
brake and chainstay bridges 1/2" 4130 CrMo
bottle bosses stainless, dead-ended
rear rack mounts
cranks 175 mm 26-36-48t
cassette 9-speed 11-32t
rear hub spacing 135 mm, 2.5mm narrower if possible
steerer 25.4 mm threaded
stem 80 mm Nitto Technomic 26 mm
bars 45 cm Nitto Randonneur 25.4 mm
nitto shim 26.0->25.4 mm
i assumed a lower headset stack of 14 mm and an upper stack of 19 mm based on info in Paterek and specs on the Harris Cyclery site. this is until i can get a measurement of the actual headset to be used, likely a Ritchey Logic.
I decided to design for a mid-length stem, so in the event that I'm off on the TT length, I'll have a few cm leeway available in both directions.