I've tried to find info about this on this forum and through google but I can't find the exact issue addressed.
I'm looking to do my first triathlon next May (Busselton 70.3).
I've been riding for years, currently on a MTB, though previously on a road bike, and regularly do distances up to 100km.
I need to get a time trial bike for the triathlon, however I have limited training time other than to and from work due to work/family commitments, currently managing about 2 hours a day by stretching out my commute to 1:00-1:15 each way. The MTB is great for this as it is rugged and reliable with disc brakes for the wet days (I ride every day - even through storms).
I will need to put a lot of time in in an aero posture prior to the event for obvious reasons, which for me means doing it whilst commuting. A super-lightweight time trial bike would not be optimal for commuting and is clearly not going to last well as a daily commuter. As I also commute in the wet I would ideally like disc brakes on any commuting bike as well.
What are peoples thoughts on getting a hybrid type bike or lower spec/more durable road bike with thicker tyres/tougher aluminium rims/disc brakes more suitable for commuting and setting it up to ride in the aero position for training purposes?
My thoughts are that riding a heavier bike with softer/bigger tyres can only make your legs stronger - a bit like adding a few degrees of slope to your entire ride. Is this a fair assumption?
Is it possible to simulate the riding posture of a time trial bike closely enough to be valuable as a training bike?
Obviously I would be putting many hours on the actual race bike in the final month before the event.

