Why do people use aerobar spacers? Why not just use spacers between head tube and stem ?
Some tests have shown that pedestaling the aerobars results in less air resistance than achieving the same position through spacers on the steerer tube.
Some new bikes like the Felt IAx series have no room for headset spacers(unless you buy a frameset with an uncut steerer tube). With the low stem clamp height there are very few stem options to change the fit. In that case you would use aerobar spacers to adjust the fit.
Thank you. I have rode the same position for years but being 60 having had back surgery a few tears ago I am finding it harder to see down the road in my low position. Thinking about raising aerobars about 1 inch
Two reasons:
-
Aero
-
They may want to position the base bar and the aero bar independently.
I do think however, if you’re racing with a bento box, depending on the shape you might still be better off running the base bar up higher on the steerer tube and less spacers on the aerobar.
i have heard the aero argument also - but i don’t know of the data. i do know the pics i have seen of pro cyclist’s tt bikes are heavily stacked in favor of more spacer and lower base bar.
i see the bento box argument here - i would add that to get the slope of the aero bar extensions to block the face a bit - that would seem to favor NOT going super low on the base bar also. i think there is an ambiguous uci rule (what? ambiguous uci rule?) about the amount of upward slope allowable for the extensions.
my own experiment has been to reduce the the amount of risers from basebar to allow the slope of extensions (and my hands) to better block my face/head a bit. sincerely, rick
It seems reasonable that introducing spacers between the base bar and extensions/arm rests could reduce drag compared to raising the stem using steerer spacers. This is provided the base bar to extension spacers are aerodynamically profiled and the overall effect of the change is to reduce complex interaction of components and provide a clean front end. It also depends on how aerodynamic the steerer spacers alternative would work out. If you have aerodynamic spacers and/or a fairing behind the stem such as the TriRig spacers and an aero bento box then the steerer spacer option may be better. of course you’re limited on the amount of rise you can get with steerer spacers (normally 30mm max spacers to avoid undue stress on the steerer tube), whereas extension/pad risers can potentially be much higher. Some allow 85mm+ of stack increase making them much more versatile so long as relative position of the base bar isn’t a problem.
Spacers are usually cylindrical, while many of the better bars have airfoil-shaped armpad risers. There is more than an 8:1 ratio between the drag of a cylinder vs the drag of a decent airfoil. That’s the theory.
In practice, if you can give the armpad risers clean air (lifting your fists out of the way of the airflow, for example) you will get a measurable aerodynamic benefit.