Triathlon - Seat pack or...

Hi Guys n Gals. I have a question that on the surface really seems elementary to me but I just don't have an answer. A customer comes in my shop yesterday with his Tri bike. His saddle is slid forward on the rails and he has a pair of rocket launchers behind it that are mounted on his seat post. He has a Bento box for his nutrition but he also wants a pack for his CO2's, tube and plastic tire iron. Obviously space is non existent behind the saddle but he does not want to carry his spares in his jersey pockets. Any ideas and recommendations for where to stash a pack in this situation?

For Tri's everything I need usually fits on my hydrotail. However if it didn't fit I would most likely just replace one of my waterbottles with a pack. Most likely the one on my down tube since I rarely use it, and in most races don't even carry one there. I usually use my handlebar water first, then my hydrotail water, and unless I'm riding for over 3 hours its usually enough. So if stuff didn't fit on my hydrotail I'd probably just get a pack on my downtube, or even just throw the stuff in a bottle and put it there.

Just my 2 cents.

I drink a lot of water. Big guy, I sweat a lot. I carry two bottles on an XLab speedwing, and one aero botttle on the seat tube. I am still able to fit a small seat bag on the speedwing. Holds two CO2 cartridges, 2 tire levers, a mini tool, a small patch kit and one spare tube.

I just don't get it personally. We go out and spend thousands on an aerodynamic bike, hunch over on 15cm drop handlebars and then put large cylinders all over our pretty bikes. There is a better way in my opinion. I think a chopped off water bottle would serve well as his flat kit in his rear launcher. That still leaves one rear bottle, at least one frame bottle and one on his aerobars.

Personally, I encourage everyone to cast off their plastic cylinders of aero-oppresion and rear mounted monstrosities. I've done an ironman with one bottle on my aerobars, and one on my seattube and I think going for just one on my aerobars would be doable. and I digest...