Stack height/Stem Angle

Triathlon Forum
1

I’m riding a Cervelo P2K with 50mm stack height (5 x 1 cm spacers), and using a Profile BSC fork with an alloy steerer, and +6 degree 100mm stem. I’d like to switch to a Reynolds Pro Aero fork, but I know that according to the 1.5 x tube diameter (1 in steerer) I can only use about 35 mm of spacers safely. Therefore, I found a stem with a +25 degree rise (Profile H20). I calculated that I can get my base bar in the exact same position using a 110mm stem with the 25 degree rise, and going down to 15mm of spacers. Also, I’m using a Syntace Stratos/c2 bar combo.

I was wondering what your thoughts are on this setup. Would going to a stem like this change my bike’s handling at all? Also, so as to not cut the steerer too short to leave room for future adjustment, is it safe to run additional spacers above the stem, and how many would be safe on a full carbon steerer? Thanks for your help

2

With a 5cm stack height and a positive ride stem, my GUESS is that you have a frame too small for you.

3

Somewhere along the line, you are going about this the wrong way. Here are the offhand possibilities that come to mind.

You have a steep seat angle bike, but are riding up high anyway. Maybe you would be better off with a road bike.

You have a bike designed with a short head tube to accomodate aggressive positions. You don’t have an aggressive position, so maybe you are on the wrong bike.

You have flexibility problems that stop you from getting a good aero position.

You have a 650c bike, but you should have a 700c bike.

You have too small a bike.

You have a poor triathlon positon.

Check to see if any of the above apply to you and decide accordingly.

4

First you should determine where your elbows should be resting on the pads relative to seat height. Slowman has a mathematical calculation for this. Determine this first and then start from here.

http://www.slowtwitch.com/mainheadings/techctr/bikefit.html#Anchor-FORMULA-23240

5

Thanks for the help. I only had 7 cm of drop, and according to the formula, I needed about 9.5-11. I lowered my stem 30 mm, so I’m now down to 20mm of spacers. I looked in the mirror, and my position looks 100% better, but I don’t know about the comfort/power etc. yet. However, I’m going to go to get a fitting next week to get everything else sorted out. I guess I should have done that 4 years ago, but that old position was just soooo comfortable, albeit not too aerodynamic and too upright. Anyway, thanks for the criticisms.