hello,

I recently got a pro bike fit. Everything went well, but now as my riding skill and comfort has increased, I want a more aggressive/aero position. I want to drop 1 spacer thus lowering the stem (it has about 3 1/4'' spacers on there). Will lowering the bars 1 spacer throw off the entire fitting? Or will it simply change the aggressiveness of the riding position? Should I do this myself or take it in?

Shouldn't change the other components of your fit much, if at all. But do it slowly, a little bit at a time. For example, move the smallest spacer above the stem. Ride for a while. Then move the next smallest spacer above the stem, putting the smallest back below if needed. Ride for week or two at each adjustment.

You'll figure out when you've gone to far.

how can you tell/feel if it has gone too far?
also, will it effect the cables?

Your back or your wrists will tell you. It may take a few miles, but they'll let you know.

as DScott said, one or two spacers shouldn't change much.

if possible, though, go back to the guy (or gal) who fitted you. most good fitters are happy to make adjustments for previous customers. he or she should have no problem helping you to lower the bars a little without messing up anything else.

"too low" is when you're so far dropped that your body is closed - your hip-torso angle is too acute.
that wil lead to knee problems.

I had a $250 Retul fit. Then I started getting a lot more fit and a lot stronger. I ended up flipping my stem. The next week I removed a spacer. Two more the week after that. Eventually I had all the spacers removed and had to flip the position of the bars down to accomodate an even more aero position. It didn't affect my fit one bit but your mileage may vary. I was nervous about "screwing up" my fit as well but it ended up not being a problem at all.

yeah...so making this adjustment only effects position....not fit.

No, you will change reach a little bit as you lower the stem.

Good post. I'm thinking of doing the same. Actually, I'm going to do it. One spacer and we'll see how it goes.

As you lower your stem it will affect your reach, but it will also affect your center of gravity slightly. Do a bit of a search, and you might find people suggest you scoot your saddle back a bit.

Do this. Stand straight up and stick your arms out straight in front of you. Now try to move your arms forward about 2 inches more and see what happens to your butt.

As you lower your bar, you change your reach, and your hip angle. So yes, it does mess with your fit, as your hip angle plays a reasonably big role in the fit. You'll also end up with slightly different weight distribution, etc.

Check with the guy you got fitted with.

Really? With only a 1/4" spacer moved from the bottom to the top, it will really 'screw up' the fit. Well, I would certainly try it and if it did not work, reinstall the spacer. Hell, I would take them all out and ride if for awhile. Certainly would not screw you up for life. You could always bring the 4 and 5mm allen wrenches and swap them on the ride.

As for the cable lengths, if you are going lower, it probably not going to cause much difference, moving the stem higher, may, depending on the original set up.

Common, 1/4" is almost nothing.

Well it's the difference between my knee killing me and my knee feeling perfect for an entire ride when it's with respect to my seatpost but I would agree with you that my stem angle had little effect on my fit and I changed it dramatically over time.

I don't know. I think I might be the only one that has a "ditch all spacers and HTFU" philosophy, but seriously just get rid of them and start riding. After a few rides you'll be totally used to it and it will feel normal. The way I see it these bikes weren't made to be used with spacers. They only include spacers for new riders that are coming off of hybrids or other types of bikes that put you in a more upright position. They also make riding easier for people with poor flexibility due to injury or people that have big bellies. IMHO spacers are just a crutch. The sooner you get rid of them the sooner you HTFU and get used to it. Why waste time by going 1 spacer at a time and have to repeatedly take off your stem and bars? If you feel otherwise and insist on using spacers, you should have purchased a "performance" aka endurance geometry road bike with a longer head tube that doesn't require the use of spacers. It kills me when I see bikes like the Roubaix with a stack of spacers on top of that. Yuck.

Jeez, and I thought I was the stem Nazi.

Some riders need spacers because they are new to the posture and need time to stretch and acclimate. Some just don't see the point of going lower than a certain point. And some need to ride a smaller frame in order to get a decent top tube length.

My starting point is with the brake hoods a couple of centimeters below the saddle. Above that, you might as well be riding a Townie.

A tip: as the torso becomes more horizontal the center of gravity moves forward. To avoid excess pressure on arms and hands move the saddle back a bit, and lower it a bit less to account for the extra stretch. And then, if you find yourself reaching too far, consider a shorter stem. But remember that most stock bikes already come with pretty short stems.