Consult the UCI article “Specifications for a Competitive Bicycle”. It may be Article 64 or 67 if my memory serves me correctly, which it frequently does not.
I know a guy here in Socal who regularly TT’s on an IO. There is no braking surface to speak of, so if you have to slow down quickly your screwed. Lock up the rear wheel, skid and hope for the best. The only other obstacle is price.
In the US, at least, Ironman races (mostly) follow USAT rules. I suggest that you get advance approval for such a device, based on the following rule:
**5.12 Untraditional or Unusual Bicycle Equipment. **Any unusual bicycle construction or equipment to which the specifications in Section 5.11 cannot easily be applied shall be illegal unless prior approval is received from the Head Referee before the equipment is used in the event. Any violation of this Section shall result in disqualification.
It may not be possible to contact the head referee sufficiently far in advance, but you can always contact the commissioner of officials, Charlie Crawford.
Thanks mate, I saw that rule and thought it’s a lot of money and hassle to get there on race morning and be told you can’t use it, so I will try and contact the race organisers and ask their opinions before I switch. Although it is notoriously hard to get a reply from these guys!