If I were to order a new triathlon specific frame, and were to have the bike custom fit, like from Guru for sake of example, would it necessarily mean I could change anything I wanted on the bike. Or are geometry options only available in certain parts of the frame? Meaning, once everything is fitted to my body, could I, say, make the head tube as short as you want? Probably not I am thinking.
So…there in lies my question. What are the limits of a seemingly limitless option?
No. You cannot change whatever you like. Well, you could, but the result could be disastrous in terms of bike handling. There are limitations in terms of the draft (what bike dimensions result from your fit dimensions). A good drafter will recognize these issues and can usually work to accomodate most of what you want. Serotta’s drafter is one of the best in the biz, and I believe Ves does the draft for all Yaqui/Mandaric frames. Certain configurations would result in things like a downward sloping toptube (opposite of a compact frame), too steep or shallow a head-tube angle, etc. But any good custom shop will catch these things.
I don’t believe that anyone will make a headtube shorter than 9cm. I could be wrong, but I think that’s typically the limit - barring any really strange frame designs, at least.
That’s the smallest on any of the cervelo bikes. 90mm is really short, though. If you want shorter than that, just get an adjustable stem. On Gary Tingley’s recommendation, I purchased a Ritchey Pro adjustable. Very nice. The adjustability is very, very good. Plus the design is very sturdy. It take some work to adjust it, but you certainly don’t feel like it might slip, as there are many “teeth” holding the stem in place. It is NOT held in place by friction, but by the splines. Very rugged design. Not a weatherweight, like the WCS, but still pretty reasonable. Stems are one area where I don’t mind a bit of extra beef…
As has been mentioned before
with custom bikes it is strictly GIGO
as in garbage in garbage out
you start with a fitter with no experience fitting, let alone bike building you can get a bike that fits your physical dimensions but rides like crap.
all of the dimensions of your bike have a effect on the ride and handling of your bike.
Your question, if you were to make the head tube as low as you want… to a degree… limited by the diameter of the materials you are working with.
Now lets say you take your very low front end bike… your ability to get that low is limited by your innate flexibility so to compensate you make your bike steeper now all of a sudden when you actually ride this bike too much weight is on the front end and you crash everytime you ride it cause you are just not stable enough in the aerobars…
A experienced custom bike builder would take into consideration your body your flexibility and your desires for the characteristics of the bike and come up with something that would be appropriate… It is a lot of tweaking and I would only trust the most experiences builders to order a custom bike… remember with a custom they build it and you bought it.
If you are going cutom I would definately reccomend that you go to the people who come highly reccomended on this site