I see she ran that securing system but with only one bottle in T100 London. So your stacked arrangement has not been tested (by her) in battle (ETA: to see whether it’s easy to get the bottle in with sweaty hands). I assume you have chosen to have the bottle cages at an angle for ergonomic/security reasons (the consideration @desert_dude mentioned), given the CFD shared up thread by @ijaero suggests horizontal for BTS is the way to go?
That looks a very neat economic cobble: just add one of Nick’s straps to secure it.
Rudy, Sam, Trevor, KB and Magnus have tested the double bottle set up and while the default bts bottle angle is 2°, when the athlete angles the saddle down further for bike fit reasons, the BTS bottles increase their angle.
While testing has shown that the double bottle BTS set up is more aero, Skipper has found three different times in the wind tunnel that his single bottle 45° angle is more aero for him than a single horizontal bts bottle. And with Harry of Evolve running those tests, we trust him on that finding. He’ll test the double bottle set up next.
We do find that people with shorter arms definitely struggle to reach the more horizontal rear bottles, especially when the bottles are approaching 1 L in volume and are so long. In those cases, we suggest that athletes use a 45° angle bracket like this to attach to the bottom of our saddle: ICE Bottle Cage Riser – Bent Up Cycles
Definitely takes practice in training to gain the coordination to work with those bts bottles
I actually asked Josh P this via text (ass aver aero benefit), and got an answer in a relatively recent Ask Josh Anything episode and the answer was that he couldn’t detect much of a difference either way (they tested it in a tunnel, evidently). That disappointed me because it seems like it should work to help. But I assume he is right, as he clearly looked at it and knows his stuff.
A side entry cage helps a lot - PRO PRBC0026 alloy side entry is fantastic, because its alloy you can squeeze/bend it tighter and I’ve never lost a bottle, even when testing the setup thrashing my gravel bike.
This works when you have a bike tube under/behind the side entry cage. but when we tested this upside down and under the rear of a saddle, the downward forces of a 1 L bottle pulled the cage open. This is why the cage we are about to release is a solid circle with no openings in the design. Most cages have a slit in their cage to make it easier to pull the cage off of the tooling during manufacturing, but for a BTS cage, that creates a point of weakness that can only be overcome by making the internal diameter of the cage smaller in an effort to hold the bottle tighter, making it more difficult to get the bottle in and out of the cage.
Positions have really progressed over the years so I think the dates add context. For the 10 year anniversary of the “Win Tunnel” we looked at the average CdA of the 3-4 World Tour Teams that came through the tunnel. In 2014, the average world Tour TT rider was 0.22, with <0.2 being very good and the absolutely lowest numbers we saw where in the 0.18s.
Fast forward a decade and nobody is above 0.2 anymore 0.18 is standard and <0.16 is now crazy good.
What I love about being active on Forums again is that the collective nerdiness of a thread like this outdoes what any full time aerodynamicist can do on their own.
Based on where this thread is headed I was starting to think about aero saddles, and just then “boom” here you are with that post.
Also never expected we would reach an almost 100 post discussion about the aeordynamics intracacies of bottle placement.
With your retention clips this makes a lot of sense as well, because I’m assuming you’re not going to squeeze the bottle so tight, correct? Some of the guerilla cages spray some nutrition out they squeeze so tightly.
Has anyone tested two BTA bottles but instead of stacked vertically they’re stacked horizontally? Or even 3 in a pyramid shape, with the new rules seemingly allowing it.
That’s right.
Jason West has been using our new bottle cage for a year and a half and because he only uses 18 to 20 ounce bottles, he has not needed to use the retention loop.
The thing is, even with the gorilla cage, when we mount it in the more horizontal position as on our V8 saddle, 24 ounce - 1L bottles vibrate their way out even with the extra grip cages, so the user ends up using our retention loops anyways. If that is the case, there’s really no need for a cage with an absolute death grip.
Like most cages, they have a split in the cage to make it easier to remove from the manufacturing tooling, which drives the cost of the tooling down substantially, and slightly reduces the per unit manufacturing cost (pre-tariff - I joke).
In their new design above, you can see they’ve kept the split, but added a rubber band. This is because when there is a split in the cage and you have a 33oz bottle full of liquid in the cage, that bottle’s mass will cause the cage to open up some when going over bumps. I found it difficult to remove a bottle with their old design; I’m not sure how much more difficult it will be now that they’ve added a rubber band to increase the tension/grip on the bottle.
Our cage has no split, has a shape that will also hold the narrow bottles handed out on IM courses, and makes removing/returning the bottle out/into the cage easier. Planning to release it before April.
With the weight of a 1 L bottle pulling against the cage, those cages can become progressively more loose as the ride goes on. Also, when mounted upside down, that tab that would typically be up against a down tube or seat tube now begin to interfere with removing the bottle.
Huh? I’ve used cheap cages like this on all-day training rides and never had a bottle come out, let alone have a cage loosen up. Idk how you’re mounting it that the tab is in the way but the bottle isn’t.
Are these values at zero yaw?
How do absolut CdA measured by different methods (wind tunnel, velodrome, aero sensor outside, CFD) generally fit to each other?
If mounted to the down tube and seat tube, you are spot on. If mounted upside down under the rear of the saddle in a horizontal position with a 1 L bottle in the cage, these metal cages stretch
If looking at the images above of Rudy and Jason, when a bottle cage is mounted in this position, A 1 liter bottle can apply enough force to break a CNC aluminum bracket, which gives an idea of the amount of force a full bottle can exert when going over bumps, so a metal cage that can be flexed by hand to open/narrow can also be forced more open by the water bottle when mounted upside down and horizontal to the underside of a saddle