I've been riding with a bottle filled with isotonic drink + hydration backpack with plain water for quite awhile. Recently my bottle stated to fall off on descents (not the best frame design + increase in speed). I'm looking for alternatives to frame mounted bottle cage that will suit aggressive trail riding. Solutions like Source dual bladder won't fit, because once you had a sweetened drink in your bladder it's just a matter of time before mold starts to grow there. I've looked on runners belts, but 600ml is way too little for hot conditions. Assuming I want to separate between sweetened electrolyte drink and regular water, and a minimum of 1l liquids all together, what are my options on the market nowadays?
My bottle holder under the frame (the third) is also prone to dropping its contents. That's easily fixed with an elastic strap round the bottle and down tube (I use an old reflective ankle strap or bungee cord. I doubt many people will be drinking from a bottle mounted there while riding anyway, so the extra difficulty of getting it out doesn't really matter.
The cheap aluminium cages can be bent tighter, but with plastic cages it's easier to pad them out using an old inner tube, cable ties, and/or duct tape.
Two-bottle belts are available -- I have an old one that I sometimes use if I ride then run. Mine takes 800ml bottles happily, but anything bigger would be awkward.
First of all: You mention that the placement of the bottle mount is bad. There are adapters which allow you to mount a bottle cage without frame holes. E.g. SKS Anywhere, Minoura or this set. All look rather flimsy though. Mounts for the handlebar or behind the saddle usually look more sturdy, if you have space there.
There is also the Salsa Anything Cage which allows you to mount and tie down anything anywhere.
If a better, more vertical mounting point for your existing bottle cages doesn’t solve the problem, maybe you should get better bottle cages. For example I use these Elite bottle cages with various normal ~800ml bicycle bottles on my cyclocross and I’ve never lost a bottle (except in a 40km/h crash, but that doesn’t really count). They also seem quite popular.
I would like to summarize all the common wisdom that was mentioned here. Note I'm talking about MTB enduro/all mountain/aggressive trail riding that involve hammering down downhill style trails, with roots, stones, drops above meter height. Also I assume your frame does not have any bottle cage mount, which is common among modern enduro bikes (Nukeproof Mega, YT Capra, Polygon Square One)
- As to current state (fall 2017) there is no ultimate solution that has a mount for both sweetened drink bottle and regular water bladder. In a perfect world I see it as a bladder backpack with a secure belt pocket for bottles size 500-800 ml.
- There are solutions to mount your bottle on the frame, all of them lame in a different way: Velcro mounted bottle cage (less lame), on the bars (very lame), on the saddle (also very lame). I guess there are exceptions, but for me none of those options will fit, because a. the only place I can allow another 750 g. of weight is close to the bike center of gravity; b. can't see most of those options survive aggressive downhill hammering.
- There is a nice solution by Source, but you should remember to do your best to clean it after a ride ASAP and store in the freezer, otherwise you'll share your energy drink with other forms of life (mold).
- There are runners belts that should take 2 bottles of volume 500 ml, but that's not officially mentioned on brand's sites. @Chris H mentioned that his Karrimor Duo X holds bottles up to 800 ml. volume.
- Another option (and IMO the best one) is to separate between hydration & energy needs and add sweeteners free salt tablets to your hydration bladder and use gels, snacks or jelly candies to restore energy. This way you can care less about your bladder maintenance, avoid aftertaste if you decide to ride with the same bladder after sweetened drinks and plan your carbohydrates intake better during the ride.
I think you can fix this by buying a better water bottle cage. The Camelbak podium, especially older ones have a ridge that can fit into water bottle holders well. When paired with a water bottle holder that can exploit this ridge then it is a very secure fit. I think you should go to a bike store and look at different water bottle cages and bottles to find a pair that fits really well.
I recently saw a bottle holder in a shop that consisted of webbing and velcro. The design was for a bottle smaller than you describe, but you might be able to make your own.
With a flexible cage you can fit in the bottle you want, and use the position on the bike that suits it best.