Oldave’s set up above is interesting. The fork is probably 8-9cm longer than the rigid fork the Kili was designed for, which explains why the bb drop is just about zero (design would be 3-3.5cm). As has been said, a zero bb drop would put off a lot of punters, but then again Chipps on STW would say bb drops are for wimps and real men don’t have one. OK, so personally I’m a wimp, but clearly a zero bb drop is not an impossibility.
I think the other point about Oldave’s design is that he has a longish stem and the bars appear to be pointing forwards if anything. If you’re going to reduce the head angle, in this case by about 5 degrees (it’s 0.6 of a degree per cm), you need to speed the steering back up by using either a shorter stem or swept bars or both. Oldave hasn’t done that. He also has his saddle way forward, so combining that with the grips position, his weight must be well forward and the whole thing is slowing the steering down like crazy.
Mention is made above of On-Ones, but Brant Richards now has his own brand called Ragley. His geometry gives a 67.5 degree head angle with a 140mm fork sagged 40mm, combining that with a short stem. What struck me about that is that folks come on here sometimes saying ‘can I put a 140mm fork on my 1994 Fire Mountain, as I like a bit of bounce?’ And they tend to be told in no uncertain terms that it wouldn’t be a good idea. But in fact a 140mm fork sagged 40mm on a 1994 Fire Mountain would give a head angle of just over 67 – i.e., very similar to the Ragley’s geometry. And it would be stupid to deny that Brant Richards knows what he’s doing.
I think the point is that with longer-travel forks, not only do you get more sag, but there’s also a bigger head angle change between the just-riding-along compression and the heavily-loaded compression, say in a sharp downhill corner. If you have your bike set up at 71 degrees in just-riding-along mode, the head angle is going to ramp up under hard cornering and the whole thing is going to get a bit tricky. That’s where the thinking behind the Ragley’s 67.5 degrees comes from, and combined with the sort stem you still have sharp handling.
My message to Doctor B is that 100mm will not cause a problem, but you might want to consider bringing your grips backwards a bit relative to the steerer axis. And remember that the position will be a bit higher and your weight will be a bit further back, leading to a more active riding style. It’s not either right or wrong, it’s just making a retro bike handle a bit more like a modern bike. Whether you prefer it is just a matter of personal taste.
