Elite's carbon bottle cage is £49.95 Campagnolo's Record cage is a staggering £74.99 (but you do get a bottle too). Most road bikes take two. So that's well over £100 for a full carbon set up. Blimey. But carbon cages are good, they don't bend or break easily and just as importantly, they 'pimp your ride'.
Weight-wise a carbon cage saves about 50% over a standard (already lightweight) aluminium one but we're only talking about an overall saving of about 50 grams which ain't much. The lightest we've found is Langerbein's kevlar cage, available from Posh Bikes, which looks a bit odd but weighs only 4.5 grams, and costs 30 quid. Looks like a pair of laces though.
As for this Planet-X cage, well the function is good, the cage holds the bottle very tightly so there's no need for rubber grippy bits or having to bend it to fit. Bottles slide in and out effortlessly and sink into place using the spring in the material to hold the shoulder of the bottle. However the snug fit does mean that it will wear any printing off your bottles in time, but all cages do eventually. We used 500ml and 750ml bottles without any problems, no rattling or jumping out, even with really full bottles on rough roads. We tried to eject them, but they just wouldn't budge.
On close inspection the cutting of the shape is a little wonky in parts, but it's smooth to touch and the matt finish is classy looking and, unlike aluminium, it won't corrode and goo-up with energy drink. Simply take them off and wash them, they look like new. There are two slotted bottle cage bolt holes and we like the fact that you can adjust the height of the cage and align them perfectly. Use a washer on the bolt though as the holes are a little on the large side.
After using Planet-X's cage I can't really see why you'd want to buy another carbon cage, it's the cheapest we've found and it looks good too. At £18 it's a bargain. They are available from the Planet-X website.
