Water bottle mount

It presents almost no aerodynamic drag since it's hidden my behind my butt and thighs.  But it also allows me to carry more bottles as well for longer training rides and/or longer races.  I use one of the holders back there to hold all my repair gear too, so I don't need a saddle bag.  I have a container that fits in like  a water bottle but still holds 2 spare tubes, tire levers, chain break, multi-tool, and CO2 inflator.  The CO2 canisters attach to the mount as well.

Most of my training rides I look like I have enough water and gear to go do a double century by myself though... but more weight during training = more strength up hills right?

What container do you use.  Something specifically designed to fit in the holder, or something you rigged up?

To be able to carry more bottles. On my bike I can only put one bottle on the seattube, so if I'm going for a long, un-supported ride I need the extra hydration.

I don't race with it though, since 70.3s have bike aid stations. Just use the bottle on my bike for sport drink and re-fill the aerobottle with water from the aid stations.

 

 

Hello

I have the two bottle mount behind my seat. 

Watchout if you get this set-up as it makes getting on & off your bike more difficult. You really have to throw you leg higher to get over the bottles.

I have found during longer bike rides that I only drink from bottle down on frame and use the bottles behind me a cooling water dumped on my back & chest.

I guess for a longer unsupported rides they would come in handy.

The bottles will fly out if you hit a big bump like train tracks.

Kevin 

Neverreach for the win.  No bottles to grab, or eject, but an extra 64 oz of water off the back.  You don't have to leave aero position to drink. 

I've never had an issue with bottles coming out of my cages behind me.  So I think it depends a lot on design and what kind of cages you have there.  For one, make sure the cages are angled back, that helps... second make sure the cage are the kind that are really tight on holding the bottles.  The one I have works awesome and it actually takes some effort to remove the bottle, which is why they don't fly out even, even with cattle grates or train tracks or giant pot holes where you think "Wow, can't believe I didn't get a flat from that one"


As for that tool carrier I found this at a local bike shop a few months ago... I love it, especially since I put that cage on my seat... the price made me wonder if it was worth it, but in the end I'm glad I spent the money.  It's not like that $20 would still be in my wallet, it would have found it's way towards buying beers or something I'm sure.

http://store.trekbikes.com/jump.jsp?itemID=1125&itemType=PRODUCT&path=1%2C2%2C262&iProductID=1125

For the record, a behind the seat system does NOT provide an aerodynamic advantage. It actually is less aero than a front bottle or a bottle on the downtube. Having said that, I use a HydroTail rear system as I can only carry one bottle on my frame and need more for longer training rides. For races, I use the rear system only with two bottles and my repair kit strapped on the back of it.

X2

Back in the spring I read a study on the bottle locations and the Areo advantage of each.  Behind the seat was actually the worst place to put bottles for aerodynamics. The bottle on the downtube actually increased aerodynamics slightly. Then other frame mount bottle was second best, then the front bottle. This study used regular round bottles(except the front). Yes it was with a rider on the bike, I'll try to find the article.

Aerodynamics are very complex, just because the bottle are behind the rider it does not mean they don't have an effect on Aero.

I only use the frame mounted bottles, in a HIM I do bottle exchange. Have not done an IM yet.
If I only had 1 location on the frame to mount a bottle then I would add some behind the seat.

wow!  They sounds evil...   I am ditching those saddle mount! 

I recently put a Neverreach on my bike and other than the fact that I feel so darn guilty putting something so UGLY on my beautiful bike, I love the system.  The only problem with it is that I have no way of knowing when I am going dry.  It does significantly change the balance of the bike when it is fully loaded with 64 oz.