Why not use a simple bottle cages and water bottle between the tri bars....lets face it - how many of us actually sit on a tri bike like wiggins for a speedfill to be effective?
Because it is a large capacity and easy to refil and drink from. Come on, it's not like we are Bradley wiggins and have a load of water boys to fetch us water in conventional UCI legal bottles.
i had the speedfill between aerobars one (which had 2 compartments) and once i'd stopped it leaking and changed the tubing end for some brewers tubing (softer so it doesnt lacerate your mouth when going over bumps). I liked it a lot at IM zurich, it takes time to get used to the bike handling obviously. I've got the one that goes into the bottle cage now but havent used it yet!