I pass this information along as a licensed Provincial C commissaire.
If you are doing a time trial with an OCUP, Provincial, or National status, there will be a commisaire assigned to the bike check. Your TT bike must meet the OCA guidelines (which are based on the UCI guidelines) for a bike. Commisaires will be enforcing these new rules this year including an update as of May 1, 2014. If you are not in Ontario, the expect the same to happen in your area following the guidelines of your regional organization (USAC in the US).
In summary, in addition to the usual bike check rules, the Handlebar Extensions and Seat position for TT bikes must meet at least one of the following conditions:
Case (3) is a new morphological exception based on rider's height and allows longer extensions for tall riders.
Unfortunately, this means that a bike no longer passes bike check on its own merit. A bike that passes for a rider taller than 190cm may fail when used by a rider <190cm if the extensions exceed 80cm.
For reference, the UCI equipment rules are here in section 1.3 (page 60).
The UCI Practical Guide regarding bike check (now slightly dated) is here.
Reading the the Practical Guide is highly recommended as it gives detailed explanation about how to perform bike check, what gets measured and how to do it for 2014.
Read the practical guide. It has some changes from previous years, and in particular, handlebar extensions are to be measured as follows:
The handlebar extensions with all their accessories (controls, levers, etc. and all their mounting accessories) must be included within the maximum distance allowed from the bottom bracket axle. Any moving parts have to be placed in the most horizontal position that can remain unsupported through their range of movement.
To check, rotate the levers to the position that gives the maximum horizontal length and allow to rest, and then take the measurement allowed from the bottom bracket axle.
When you show up to a TT expect that if you look around 190cm tall that your height will be measured such as by standing next to a tent support with your helmet and shoes off, heels on the ground and then a carpenter's level will be placed your head to check whether the your height exceeded the mark.
Remember, it is your responsibility to make sure your bike is legal. You can contact the OCA and bring your bike to their office to have it checked. Just make sure they know you are coming so their can make sure the jig is there and setup. Last season, a commissaire was present at the Real Deal TNTT prior to the Provincial TT to offer a bike check. No doubt, the same will happen this season.