Jul 4, 11 1:34
Re: Road fit protocol [Slowman]
likewise, cockpit distance and bar drop. what would you like to see in a protocol, taking into consideration the "mandate" that we tackle each axis, each parameter, individually, that is to say, we'll look at cockpit distance distinct from handlebar drop, distinct from saddle setback?
You canít do that on a road bike because hand position affects seat position, or more accurately, effective saddle setback. Unlike a tri bike, which is a relatively static position, a road cyclistís position is more variable. You can set saddle height and setback, but the moment you change hand position, whether it be reach or drop, youíll have changed the seated position as well. They are intertwined, as are all things when it comes to road fit.
Letís talk setback, as this is such a crucial part of road bike fit. I think itís safe to say that KOPS is gone. From there, youíll find a lot of opinions on what the proper amount of setback, or what the range of setback should be. I believe Retul has enough normative data to provide a good starting point for most of the ranges weíre looking at, but I find their range for setback to be too narrow. Doesnít matter, though, because before you even begin talking setback, you need to define where the riderís hands should be when measuring. On the hoods? Drops? Change that position, and youíll change the riderís fore/aft position.
Letís say weíre placing the riderís hands all the way out on the hoods. How much bend in the elbows do you want? This will affect the riderís fore/aft position. How much resistance should the rider be experiencing? This will often affect both knee angle and effective setback (which is why we take measurements at varying levels of resistance). How will you measure setback? Statically or dynamically? Those two will likely produce very different results. The key thing to remember is you canít set saddle position and simply move on. The moment you begin changing a riderís hand position or, more importantly, their pelvic tilt, youíll have changed both the setback measurement, and the knee angle at DBC; sometimes dramatically.
Letís move on to Pelvic tilt. Itís the one thing we canít accurately measure (sans driving multiple pins into the hip), but itís absolutely a top priority for a proper road fit. Without sufficient anterior (forward) pelvic tilt, the rest of the fit is folly because you cannot achieve a balanced, efficient position without first getting the rider to rotate the pelvic structure forward. Once you have this, the rest of the fit is actually quite easy, especially reach and drop, as the hands fall comfortably into position without needing to support much upper body weight. Of course, you canít achieve pelvic tilt without sufficient saddle setbackÖor reachÖor drop Ė they are inter-related and cannot be separated into their own neat compartments.
Like another poster, I, too, have revised F.I.S.T. for road bike fit. Itís worked well for lo these many years and, while I sometimes tend to dictate (or really, ďencourageĒ) positioning a little more with road bikes, allowing a rider to find their own position generally results in a good overall fit. Youíll find that, for effective seat angle, 73 degrees is to road fit, what 79/79.5 degrees is to tri fit. Seat angle is where American bike manufacturers need to wake up a bit, especially with smaller bikes. Cervelo gets it right Ė every bike, regardless of size, is at 73 degrees. From there, I have plenty of room to move a rider fore and/or aft. Anytime we get a call to fit an entire team, if itís sponsored by an American brand, I let them know Iíll be needing some way-back seat posts for most of the riders. If thatís not possible, you get what youíll see on most American designed/engineered bikes, seats pushed all the way back on the rails for the majority of the team.
If needed, I can achieve a forward ďcritĒ fit with a 73 degree angle bike; I canít always get where I want to go if Iím starting at 74, 74.5, or even steeper.
Where do we go next? Range of knee angles? Reach? This will be fun with lots of opinions and experiences, I think. Not as straight forward as tri or tt fit. I suspect Iíll learn a thing or two along the way.
Jim Manton / ERO Sports
(This post was edited by JM3 on Jul 4, 11 1:36)