questions: seatpost, saddle position changes w/ fitting

[azfiddle]

Okay knowledgeable gals out there-

Last week I went in for the way cool 3D Retul computerized bike fit I won from Carmichael Training systems (2 hours, 2 guys, 3 cameras, many angles and overall very interesting experience). I have had the bike 4 months, had a pretty careful fit at the bike shop, but wanted to try it in case there was anything else that could be improved, given that I have had physical issues (arthritis L4-L5, and a whole series of problems with my hip going out of alignment and other areas in my leg responding with problems when they try to compensate).

Possibly relevant info: I'm 5'1", with a very short torso, have a 44 cm frame Specialized Ruby, with the stock seat post but Jett saddle replaced the Lithia saddle that came with it.

Net result, they wanted to move the saddle up and forward a bit to improve the angle at my knees and hips. However, my saddle was as far forward as it can be and the only way they could move it further forward was by turning the seat post 180 degrees. (which they did)

So, I do like the change in position but....my saddle won't stay level anymore. It started to tilt up and my DH tightened it back down, but it started creeping up again.

questions
Do I need a different seatpost if I want to keep this set up? We were concerned that tightening it too much might be a problem...

Thanks for your insights

[OakLeaf]

I don't know exactly what your seatpost setup is, but the MacGyver method of making a seatpost clamp micro-adjustable is to shim the serrated part with a piece of metal cut from a can. I've had the best luck with steel (aluminum is too soft and compresses pretty quickly) folded over once to make a double thickness. It takes a little fiddling, but it can be done. Use snips to cut it and pliers to fold it (so you don't cut yourself).

Still, a micro-adjustable seatpost sure is nice, and between that and your issue with setback, I guess it depends on your budget.

[Becky]

Is it a zero-setback seatpost? If not, that would be an easy enough fix.

[azfiddle]

Sorry, can you explain what "zero setback seatpost" means?

[withm]

A zero setback seat posts is completely straight, with the mounting mechanism at the top. A set-back seatpost is shaped sort of like a reversed number "7" or rather an inverted letter "L". The mounting mechanism is "set back," typically about 25mm (but they vary) or from the actual seatpost thus extending the reach, and also changing the angle of your leg while pedaling.

A picture says 1,000 words - there are photos at this website

http://en.wikipedia.org/wiki/Seatpost

[indysteel]

Sorry, can you explain what "zero setback seatpost" means?

As I understand it, it basically means that the seatpost clamp is directly above the post itself, rather than offcenter or "set back." Your seat tube has an angle (say, 74 degrees) that effectively changes when you use a seatpost with an offset clamp. By using a zero-setback seatpost, you keep your seat tube angle the same. Some of us (most of us, I'd wager) use an offset seatpost because we need to get farther behind the pedals/bottom bracket than the STA allows. I, for one, usually need a lot of setback.

[nscrbug]

Probably a dumb question here...but exactly how does one know how much setback they need (or don't need, if that is the case)? I've had many fittings (include Retul), but the fitter never mentioned "setback" to me, so I have no clue. FWIW, the seat post on my Cannondale Synapse is one of those teardrop-shaped aero posts, so it's not like I can easily swap it out for something with more (or less) setback. Infact, I really dislike the entire seatpost/clamping system on the Synapse because small adjustments are virtually impossible to make.