1000 m elevation ain't no shit for a HIM , you might use the largest cog and if that rubs than forget about the cover. If these 6 seconds are definitely, I wouldn't even think about fiddling with a crack pipe (although, if you use a cover you can cut the hole that a regular pump head fits-that's what I did)
Disclaimer....Since I'm a MOP I don't use BBS (and don't really care bout a few seconds)........but always use the cover.

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-shoki

Yes, I found this when doing a whole lot of simulations for Western Sydney 70.3 which is very flat. A disc was only worth a few seconds, I normally use FC404 F&R.

I'd suspect the algorithm before anything else. What wind did you plug in? At zero yaw, modeled differences are relatively small. Already at the slightest wind (IE, any outdoor condition) the disc advantage grows.

I've raced HIMs with twice the amount of climbing and still go for a disc/cover, any time (as do most of the FOP). It is faster.

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ZONE3 - We Last Longer

Eternal discussion... I agree with you: Does Best Bike Split e.g. take into account rotational energy?

I think R Chung or Carl did a great post about why you should use a disc when ever you can. (IIRC Rappstar chimed in as well - that should give you enough ammo to find the post)

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Brian Stover USAT LII
Accelerate3 Coaching
Insta

The thread Desert Dude is referring to is the one to look up. IIRC, the creator of BBS chimed in to mention there were some variables that weren't accounted for when using a disc (e.g. rotational drag and the system effect of a disc giving air something to reattach to behind the rider).

When I put all my data into BBS, it says [for me] the difference between a Tri-Spoke rear and a disc wheel is 35 seconds over 180km (Ironman Canada). Just throwing this out there because I actually took the time to run this BBS experiment a couple months back.

Given how close BBS is at predicting my performance at races, I'm inclined to trust it.

Even if you want to be generous and say there is a 60 second advantage to running your cover over just a 404, is that small performance gain worth the hassle of dealing with covers and tape and rubbing and crack pipes?

Hence why I moved away from a disc and now run a dual Hed H3 Plus setup. The 15-30 seconds I would save in a 70.3 is not worth the hassle of dealing with different sized valve stems on tubes, and inflation hassles. With the H3+ I just run a 51mm Vittoria latex tube with a 30mm extender on each, and have two 80mm butyl tubes as spares. No concerns with fussing around with extenders if I were to flat.

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Favorite Gear: Dimond | Cadex | Desoto Sport | Hoka One One

Read: http://forum.slowtwitch.com/...3F_P5934889/?page=-1

Mrcooper even chimes in and says the benefit of disc is under estimated in BBS, essentially. Plus, watts to spin, if you believe that

I don't really see what the hassle is. I carry one tube, the stem length is the right one for my disk, and I have an extender installed that is the right length for my front wheel. If I have a flat in the disk I just remove the extender, which takes only a few seconds. I have no problem using my CO2 dispenser with my disk; I use an 808 with a Catalyst cover permanently installed and the opening is large enough and the cover flexible enough that it's not a problem. The additional weight of this cover is so low that there is no triathlon in which I wouldn't use it.

I haven't done any formal testing of the cover vs. the uncovered wheel due to the hassle of removing the cover but my power files suggest a significant improvement. You have to remember that BBS is a simulation and not reality and no simulation is perfect; the only time I've used BBS it was not particularly accurate. A disk in and of itself is not going to make or break your performance but my power to speed ratio appears to be among the best posted in the race power thread and I've achieved that by attention to lots of details, including using a disk. I've had one flat in five years of triathlon so I'm willing to lose a few seconds every now and then in exchange for real speed gains in every single race.