Removing spacers
 

In general, why would one not remove the any spacers under the stem? I am 5'10 with good flexibility( I can touch my toes, grab the bottom of my feet etc) and ride a 54cm Cervelo SL1. I have been Retuled by the shop that sold me the bike and put on a 120mm stem. When I asked about going lower he said he wouldn't recommend it but no real reason to why not. Another shop suggested that the bike was to small and we put on a 140mm stem. I feel more relaxed on the 140 and get sharp lower back pain with the 120 riding sustained periods of time riding low on the hoods. I thought droping the stem was more of a flexability issue than anything else. What other concerns are there?

Saddle to bar drop is all over the place. Some riders think that 5cm is a lot, while I use 9-11cm. I'm not a larger rider either.

To some extent, you can trade reach and drop, almost 1/1. Too much reach can cause strain at the shoulder. My rule of thumb is to use enough reach to maintain a small amount of knee to arm clearance when I ride with my hands in the hooks (so I can reach the brake levers) and my upper back is close to horizontal. With a lot of drop, that require almost no bend at the elbow. If the bars are high, the elbows would have to be bent quite a bit and that creates knee to arm interference.

You're looking at this backwards.

Put the bar where you're comfortable. Everything else is determined by the bar being in the correct location.

Sounds like your fitter may have had the best fitting tool in the world without knowing exactly what the objective numbers really mean that Retul gives the fitter? I can't say because I wasn't there to hear exactly what he or she may have told you.

There are a few reasons for a fitter to keep your saddle to bar drop a minimum.

Closed hip angle. It doesn't matter how flexible your back and hams are. If you are too far over and your hip angle is getting closed up at the top of the stroke, it can hinder breathing and power. Many folks don't realize that power is made all the way through the stroke. Some spots more than others, of course.

Your back and overall flexibility may be able to handle the drop but there are future problems that can arise. Neck and shoulder issues, hand pain, etc.

Anyone can buy a Retul system. But like it has been said before, Retul is just a tool. The fitter must know what the numbers mean, and how to apply those numbers to the fit. I feel a rider can be dropped a little further than some of the normal ranges if flexibility allows but the hip closed angles MUST fall within the ranges I like to see. Most people I fit make more power up a little bit more than the full race position, have more comfort yet still retain a good aerodynamic position.

Good luck.

I was thinking it may have to do with hip angle. I was just curious why it seems that many racers bars are slammed and I was advised not to. Of coarse I do not know if they have been fitted. They may have done just because that's what racers do. Probably my reasoning behind it also. Thanks

Being lower is not always better. At some point, you can restrict your breathing (which will slow you down) even if flexibility isn't an issue.