With a lot of the new tri bikes having very short head tubes, what happens if you add a new fork so that you can mount your stem higher up? Besides looking funny is it unsafe or does it cause any damage to the fork? How tall of spacers can you have on a steer tube before it causes problems.
Beyond the performance loss of pushing all that air with your chest now that you are sitting up, too many spacers can put a lot of stress on a fork for which it was not designed. If you are doing it on a temporary basis to slowly work your way down to a lower position then I doubt it would be a problem, but I would not trust more than two or three inches of spacers under my stem as a permanent solution. It would be better to buy a stem with a lot of rise and/or aerobars with more rise on the armrests. Really it would be better to buy a more appropriate bike, but most people are not going to do that.
Chad
Correct me if I’m wrong, but I don’t think using a larger rise stem or large rise aerobar rests would be any more or less safe. Assuming his body is positioned in space at the same point, the same amount of torque is being put on the steer tube.
One more thing to consider would be to not use a carbon steer tube fork. IIRC, those are more sensitive to stack height and safety issues.
Your point on an aluminum steerer is a good one.
As for the other issue, I’m not an engineer, but I would think that bracing the stem on the top of the headtube/headset would make for a stronger connection. Sort of like if you were to stand on teeter-totter where one end is secured to the ground; jump up and down in the middle all you want and it will be strong. Do it on the end and it is going to create a lot more stress at the point where it emerges from the headtube/or pivots on the teeter-totter.
Waiting to be flamed.
Chad