Just put in an order for the SC-R55D after a dozen emails with questions and requests
Communication with Justin is always smooth and he usually replies within a day (if not an hour or two), though I feel bad about bothering him for a single frame.
I think this frameset looks really good. Similar to the Tavelo Arow, but some differences in shaping (look at the TT-HT junction), plus this frameset has SRAM UDH, a round steerer (much preferred from a safety perspective), concealed dropout holes. Compared to the older SC-R52D model, I think the fork crown and seatstay junction shaping is much better, as well as the deeper-profile fork legs.
I'm buying this frame for the aero upgrade -- I won a few cat 3 road races this year on a heavy round-tube aluminum gravel frame, but it will be harder to continue with it at the Pro/1/2 level. Aero-wise, I think the SC-R55D is probably decent enough. Looking through the Tour Magazine wind tunnel tests, the similar Wilier Filante SLR tests around 210w @ 45kph with Zipp 404 wheels. For comparison, the fastest road bike is the Simplon Pride II, basically a TT frame, and it's at 202w with the same wheels. Supersix Gen 4 and SL7/SL8 are somewhere in between the two. Comparing the SC-R55D to the Filante, the fork legs are deeper, the seatpost appears narrower, the seatstays attach lower, and the fork-HT transition looks more modern. So aero performance is probably on par with the SL8, at the cost of 100g or whatever, which I don't care about.
I was actually planning on buying a Supersix Gen 4, but after trying out a 58cm model, my thighs rub against the top tube. And I think this is a problem I will have with most aero bikes with wide, high top tubes. I could size down, but then that decreases the front-center too much, which isn't ideal for handling at my height. So I settled on the SC-R55D size 535, which has a lower top tube, and front-center almost identical to the Supersix 58cm at 606mm. The downside there is that the stack is pretty low, so I might need to use a number of spacers, but I'm thinking of using an up-angled stem instead (i.e. the Simplon Pride / Cervelo S5 / TT bike strategy).
The only real downside is BB86. Not ideal for DUB of course. I'll be measuring it with a bore mic. Worst case, buy a 40.98mm reamer ($150) and/or BBInfinite bottom bracket ($200) and it's still a good deal I think.
Oh and the shaping of FSA ACR spacers is slightly annoying. Spacers are on the leading edge of the bike and it seems like low-hanging aero fruit to make it airfoil shaped like the SL7/SL8 rather than a rounded rectangle. I'll either try to print something, or maybe try using a Deda DCR upper headset instead, as the shaping is a bit better.
Unfortunately, custom paint isn't available for a single frame. So I'm getting it RTP (ready-to-paint). Going to do spray.bike, which might be a pain in the cold of ~November, but I'll figure something out.
Prices (USD): $660 frameset (including seatpost), $30 headset, $20 thru-axles, $50 additional zero-offset seatpost, $172 shipping + paypal
Thru-axle dimensions:
Frame 164mm M12*P1.0*L18
Fork 120mm M12*P1.5*L12
