Asking for a friend…
Looking at the rear wheels at Kona its obvious people are willing to ride discs at this point and the rear wheels are just work arounds. What is the exact rule? Do you need a hole in the wheel and does the hole need to be in the middle? How big does the hole need to be?
I think what you are asking is: “Is there a maximum rim depth allowed for a rear wheel in Kona”
As per ChatGPT, the answer is NO.
However, I dont know how not taping the valve hole, would give you hopes that the officials would let a disc wheel through for Bike Check In.
no is the clear answer otherwise you would have seen one already .
as for specific rule
bike starts page 17 section 5
(ii) The rear wheel may be either spoke or solid construction (disc wheel). Wheel
covers are permitted only on the rear wheel. For reasons of safety, solid (disc)
rear wheels are prohibited at the IRONMAN World Championship - Kona; (DSQ)
and in other rules to couver a disc wheel whole with duct tape is one of the few things you are actually allowed to use duct tape as they say it does not alter the product to much so no the disc whole cut out would not do
(b) Protective screens, fuselages, fairings, or any other devices or materials (including
duct tape) added or blended into the structure with the intent to reduce (or having
the effect of reducing) resistance to air penetration are prohibited. Aerodynamic
assemblies and protuberances on the head tube or elsewhere are prohibited.
Provided that the use of adhesive tape (including duct tape) does not fundamentally
alter or enlarge the general shape of the structure, adhesive tape may be affixed to
the bike (e.g., to cover valve cutout of the rear disc wheel, to cover bolts access,
etc.); (
I hate poorly written and subjective rules. You don’t need to include “for reasons of safety”. It’s also been proven over and over that a rear disc is not a danger to bike handling. Why just Kona? What about other windy courses? Eagleman is famously windy. As always, tradition.
It also requires them to define “solid”. A “solid (disc)” wheel by definition would be fully filled with material, so 99% of disc wheels are okay since they are in fact hollow.
Ok, ok, maybe they mean disc wheel as a fully covered wheel surface. What about those old discs with 4 holes in them? How different is that from a trispoke? And if that’s okay, then how small can the holes be, and how many do you need?
Super easy rule if you want to keep the silly tradition: “Rear wheels at Kona WC races shall have a maximum occlusion of less than 50%”
But as always, IM rules are apparently written by unpaid interns trying to impress their bosses.
For the Jet180, I thought it was a known thing that those big spoke pass through holes are terrible for aerodynamics, or am I wrong?
They are markedly worse than having the spokes attach to the innermost part of the rim, but it’s probably still a faster wheel than having the rim end wherever the spokes attach (basically just a standard ~90mm rim).
HED came out with a Kona-specific wheel in the 'aughts that IM didn’t allow. Not sure how it’s materially different than the wheels they are allowing the past few years.
I do agree with all you say
And the no disc rule without a front wheel dept regulation makes o sense.
It’s approaching a poop or get off the pot moment rules wise. Either ban anything deeper than 88mm in the back OR allow discs. The fact those wheels exist is testament to this.
I think triathlon specific aerobars that resemble air plows and the bottle setups despite being ingenious are also pushing a “poop or get off the pot” rules moment in the sport.
In terms of “cost” in the arms race for a while triathlon beat the UCI setups with ingenious items at low cost. Now it’s the opposite. The more restrictive UCI bike doesn’t have the insane custom bottle setups and Kona only wheels. The helmets are similar. Suits cost for a couple GC contenders or TT specialists is astonishingly more but bike for bike I feel tri is now more expensive.
This is going to sound silly(and it is) but I was there when they made the no disc rule and it all hinged on just one guy. Spelling may be off, but Dennis Hasserert was the guy on the island who was a bike racer and cycling race director in Hawaii at the time, was the one who just said discs were too dangerous to ride on the island for triathletes. He was in charge of the cycling portion of Kona, and what he said was gospel back then.
So fast forward over 40 years, and his word is still gospel and no one has yet to dislodge his original thought, even though in their other races around the world, winds are as bad or worse . It is just one of those old laws that have stayed on the books, and everyone in power since is afraid to change it. Probably a liability thing for them, as who wants to be that person in court that has to justify changing the rule after someone gets blown over and crashes. And its not quite the same as letting other venues who have worse wind use discs, but it is the changing of an old outdated rule that would put them in jeopardy. If they have always been allowed, then nothing has changed and it is the status quo. But making that change from an old standard, well for some reason that would be different…
it should never been a rule to begin with, but it was and that is the problem with chaining it. Thanks Dennis!!! Anyone know if he is still around??
So, if true, the stupid 180mm deep rear wheel (which is no safer than a full disc) lives on in perpetuity? Really??
Well the real issue is one of fair competition (with a chunk of common sense).
Either limit the occlusion % (area of wheel measured to rim edge) or place no such limit (so allow discs).
Maybe, at the same time as allowing discs, there is merit in specifying an occlusion limit for the front wheel (50% would allow 90mm rims). That would allow the change to be presented as one where safety is the primary concern.
A lot better than the aesthetics of stuffing a 2 litre bottle down the front. That just looked ugly.
Until someone is willing to put their neck on the line and make an actual change in the rules. And I see no upside to being that person at the moment. And once again, it is not about safety anymore, it is more about liability, so the other wheels are fine and do not infringe on the original rule by definition…
I recall when I raced Kona (2013) there was at least a handful of people in the bike check-in line, that showed up with a disc mounted. Heart breaking and difficult to understand how people invest so much in getting to race Kona, and not even remotely having a sense of the rules 
I guess if all race by the same rules, it doesn´t really matter if we can “only” race to a certain max rim depth.
I have been using a disc in racing & training for 15 years and in gale winds at times. But put a 45 kg athlete (I was going to write woman, but it could be misunderstood) on a bike with a deep front and a disc wheel, and that CAN mean trouble on a bad day in Kona. Especially if low/no experience riding a disc.
Put anyone without experience with deep section rims or riding with aerobars on a tri bike with 90mm wheels on the Queen K and they’ll have issues. Bottom line, run the equipment you can handle.
Almost but not entirely. Going from a disc to a deep section wheel is basically the same penalty (in terms of wattage at the same race speed) regardless of rider size, call it 8 watts. A very tall rider with high watts/high CdA is going to have less of a penalty than a small rider with low cda/low watts (at the same speed).
It’s the same as saying “all Kona riders must attach a 15cm sphere to the top of their helmet” or number plates in gravel races. On face level it appears to be the same but is actually asymmetric.
True that! But as you state, this goes for a lot of rules out there, where athletes of different size must compete on the same gear, to assymetric advantages.
Yep! You could just as easily say disc wheels advantage smaller riders, but since I’m smaller myself I argue the other side.
