So we have a class of time trialling that is just for road bikes. This is the fastest bike and rider in the UK at the moment (George Fox). I love this type of optimisation so just wanted to know if I could get the rolling resistance benefits on rougher roads at the rear (and comfort for normal riding) while still have aero efficiency at the front using slightly more extreme tyre size differences than you typically see.
I hate this type of optimisation! As the whole point of introducing a road bike category in TTs was so that people could just rock up and be competitive (equipment wise at least) on the same bike they already own for doing crits or road races. Thus making the sport more accessible to more people. Figuring out how to basically achieve TT bike speeds within the letter of the road bike rules by building a frankenbike like this is the exact opposite of what the road bike category was supposed to achieve.
Getting very off topic though! FWIW I agree with you that everything I hear from the aero experts continues to support a narrower tyre up front still being optimal for TTing on reasonably decent tarmac with no draft. And the companies that specialise in this stuff like Swissside, DT Swiss and Aerocoach are still making front wheels optimised for ~25mm for exactly this reason.
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I do love the UK for how extreme they take their equipment selection for TTâs. 10kG Tri-Bike with fairings, full length over shoes, etc for a flat road course, and then build a 5kg bike with only one brake caliper and shaved brake pads, and holes drilled in every lever, derailleur, and even frame for hill climbs. The Brits are definitely the most biggest bike nerds in the world.
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Yes, but the TT bike category still exists for those who want to nerd out and get into an arms race of aero optimisation with all the things you describe. The problem is that it turns out that there arenât that many people sufficiently interested and rich enough to do that and so the sport was declining (apart from a brief post-covid surge when TTs were allowed because you could run them within social distancing rules but crits and road races werenât). Hence the decision to roll out a road bike category to make TTing more accessible to the much larger number of people who own a nice road bike with decent race wheels and donât want to spend a load of money on a dedicated TT bike. This bike goes totally against the spirit of that and defeats the purpose of the category!
To be fair, it basically came about because CTT (TT governing body in UK) didnât do a very good job of writing the rules first time around. Theyâve now tightened them up so the bike above wouldnât be allowed - hydration has to be within the main triangle so those bottles (=fairings) behind the seat have to go, and thereâs now a maximum distance of 240mm from front of brake to rear of bar top as well as clarification that weight has to be supported by the hands, so those bars have to go. TT bikes and climbing bikes will still be pushed to the extreme Iâm sure!
Funnily enough, George Fox did say he used his Frankenbike in crit races and training rides.
I kind of agree but I still really like seeing weird and fast bikes and it is nice to see aero win over power (as someone who is genetically not powerful). I made my much cheaper and rule friendly road bike do 26.5 mph average on 268 watts average so you donât need to spend big money (I had standard tyres, Chinese wheels, alloy 38 cm bars, ÂŁ100 skinsuit etc).
UK TT scene is fabulous.
Nothing beats getting changed in a roadside bush at 7am when its -3c 
That said, its still the only competitive cycling I do 
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Is the parachute housing out back for stopping after the TT is over?