So I got one of those Profile Designs behind-the-saddle-water-bottle-racks so I can carry more water out in the remote farm areas I ride. I've seen people here refer to them as "butt rockets". The PD cages have a rubber band of sorts that holds the bottle pretty tight, and an inward protrusion to hold the bottle at its neck.

First ride, first significant bump, I hear the bottle skidding down the road behind me. I can see how the leverage of the seat tube and the arm would give a pretty good launch after a bump.

Does anyone have any clever hold-down strap solutions to keep the bottles from ejecting?

Whew; so glad I badly mis-interpreted the thread title...

Keep the bottles you are drinking from on the down tube and seat tube and store the other two in the rack in back. In back, put a big rubber band around the neck of bottle 1, under the rack, around the neck of bottle two (substitute two smaller bands if a really big one is unavailable.)

A simple rubber band (the thick industrial kind)works wonders on the PD Bottle Launchers. I got rid of mine and just use my jersey pockets for extra bottles.

I find it hard to believe that the product is so poorly designed that you have to jerry-rig it to keep the bottles in? Does it require special bottles or are you just doing something wrong? Serious questions, btw.

I see these Profile Designs "butt rocket" cages all the time, but have never seen or heard of this problem. I was thinking of installing one for longer rides, to minimize the annoyance of having to stop every couple of hours to refile, but now I'm having second thoughts.

You haven't spent much time behind them I take it. I can recall seeing bottles launched on a number of occassions. The amount of flex in the structure, combined with how the bottles are cantilievered out makes it an effective little catapault.

Also, you'll identify yourself as a tri geek, if that matters to you.

yeah i was a little frightened myself

Yep, I was fittin' to drop kick this baby to TH.

Now, not so much.

"bottle launchers" would be less likely to be mistaken for something else, and it's what I have heard used in my area.

The fix is to bolt on cages that are stiff and hold the bottles tightly. The PD cages flex and aren't that tight. Or to put the bottles elsewhere.

Possibly throwing a few loops of tape around your bottle at the appropriate place would help.

I have the seatpost mounted PD holder and haven't lost a bottle yet, but I only use it on 3-4 rides a year.

Bontrager has a version where the bottle cages are essentially reversed so the bottle containing tab is on the back rather than the front; I wonder if this would improve the reliability?

I've used the PD Kages for this and never dropped a bottle. The tightest grabbing cage I've ever used.

I was going to say Immodium. I still may. Let me think about it a bit. *goes off to scratch butt*

Weird. I have a couple Profile Design seatpost-mounted bottle cages (that I leave at my parents' place in Arizona, so I can take extra water with me when I ride in the desert), and I have the exact opposite problem:

It's nearly impossible to remove the bottles from the cages!

Definitely too tight to pull the bottle out while riding; I actually have to stop, get off, stand behind the bike, and hold the cage with one hand while pulling the bottle straight out with the other.

And it's not just one fluke cage, it's just as tight on both cages on both dual-cage mounts. (4 cages total)

No way these things are gonna launch a bottle unless I ride over a land mine.

I would search for "butt rocket" on youtube, then come up with another term when you're done laughing.

On a more serious note, the XLab Gorilla is a pretty tenacious cage designed for this very job.

https://www.xlab-usa.com/index.php?op...=16&Itemid=217

like this guy?...https://www.bikeforums.net/member.php/38703-DrPete

Well, there are tri geeks and then there is Dr. Pete, who just happens to dally into the geekiness that is triathlon.

It takes me two hands to install / remove the bottle that launched itself on a relatively small bump. I don't think they would go anywhere when I'm in the saddle, because my weight damps the road shock, but when I get out of the saddle for a bigger bump, that whole seat tube / carbon seatpost / arm makes a pretty good launch spring.

Bob, what types of bottles are you using?

I'll try the rubber band thing, and maybe create something out of an old inner tube.

And besides, we tri geeks know that rear-mount is SO last year.

Nobody is going to mistake me for a tri geek, with no aero bars, and with many fredly features like a triple, top-tube-mounted pump, helmet mirror and visor. If they did I guess I'd be flattered. I simply need more water capacity, particularly when riding with my niece, whose 650c bike has room for only one bottle, and I hate Camelbak-style carriers. I have carried smaller Aquafina type bottles in my pockets, but I'd like to take the 20+ ounce ones, which would be a little less comfy.

Sorry, I just hate boring thread titles. I thought it fit in well with the "farting in the paceline" genre. Feel free to change the title if you like.

I've managed to launch bottles even when the bottles are tightened down so hard I need TWO hands (while stopped!) to pull them out. The force from a rear bump seems to hit the bottles exactly right, unfortunately.

I've since abandoned the X-wing setup and gone to aerobar and downtube bottles. When training, I'll actually put the bottles in my jersey pockets. That rear rack is a real bottle launcher. Rubber bands prevent this, but also make it hard to remove them.

I've hit some pretty massive bumps with mine, and never launched a bottle. FWIW, though, I usually use smaller bottles behind the seat, and only put larger (750ml) bottles in it when they're empty. The bigger bottles usually start in the seat tube and down tube cages. When I do put larger bottles in the behind-the-seat holder, they start frozen solid for a long summer ride, and when frozen they tend to be a bit larger.

you can also employ handlebar mounted systems ( as seen on beach cruisers and exercise bikes ), that would go well with the mirror and top tube pump