The SC pads are roughly 80mm front to back and our Fit Services classes use the elbow just off the back of the pad as a starting point (based on user surveys as well as observations of what users bring in as their existing setups). Also keep in mind this convention is geared towards (and based on data from) the much larger tri contingent vs the smallish TT crowd (and considerably smaller still CTT-governed TT cohort).


Explained here.



or just back out from our fit charts and what's pictured that the actual leading edge of the pad reach range is ~90mm to the right of the CTT line (pictured leading edge).

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Carl Matson

Many thanks again for that, Carl. What I find interesting there is that there is arguably a general trend that people on smaller bikes are mainly trying to get lower rather than a shorter reach. The people violating the 3cm rule by the biggest margin are on the smaller frames. If the rule were changed to 5cm, most people on an XL would become compliant, but hardly anyone on an S would become compliant. The proportion of non-compliant people who would become compliant increases steadily as frame size increases. This arguably provides some support for the Shiv TT's geometry where bigger frames add reach but not stack (after the very smallest size).

So I feel there is maybe something in the data there to support the idea that small TT bikes have too little reach for a lot of people, relative to large TT bikes, even if we aren't considering the UK's 3cm rule.

Getting down into the <600mm stack region there is a huge range of reach, difficult to fit them all in though it would appear that current geo does accommodate all the short reach riders. Stretch for this sample population may also be constrained by UCI and other regs. 20mm reach for 30mm stack appears a common size slope for most manufacturers.
Are non-UCI frames any different? BMC only derivatise at the rear.

hey Steve and all-

huzzah!!

http://www.cyclingweekly.com/...ial-positions-325250

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Carl Matson

Hi Carl, yes, it seems we are effectively back to where we were in previous years, which is a subjective "keep it sensible" approach. I know that the data you provided in this thread has been used in arguments presented to CTT that the rule is inappropriate because it makes illegal perfectly normal riding positions that are well within manufacturers' intended fit ranges. So thanks again for providing such a helpful response to my thread.

happy to hear I might've helped in some small way.

ride fast and comfortable my friends.

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Carl Matson

Thanks once again Carl. How on earth do you find the time to take an interest in our little cycling backwater?!

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Developing aero, fit and other fun stuff at Red is Faster