The point is that you might be forced to work harder to move the heavier bike.
However if you are able to find the gradients needed for the harder work out and alter your route accordingly then you wouldnt need a heavier bike to achieve it.
All if this is on the flawed assumption that a harder bike ride is a better one, of course 
Not so sure I agree for sure, inertia is not the same, so you do have different demands.
The effort to accelerate to an “acceptable” speed, balance and the extra resistance from cheaper bearings etc may all contribute to making it a more demanding experience. If that simply means that you ride more slowly as a result, then this benefit may be lost, of course…
That said, getting off my winter bike and onto my TT in the spring is (was) always a very positive experience that encouraged me to cycle faster…
True. I started writing various caveats about things like rolling terrain, where a heavier bike with more inertia that is up to some speed might actually roll over those bits slightly more easily. But then as ejc says, you have the compensation for that of the extra effort to actually get the heavier bike “up to speed” to create that inertia in the first place. For city riding, where you are braking and accelerating from stationary lots, I can see a heavier bike creating more “work”.
In the end I scrapped trying to include all the caveats and looked at what I considered to be one of the main things. If you hit a big climb and you want to “work” at 300w, then other than having to hold that 300w for a bit longer as you are moving slower, 300w is 300w. If the heavier bike forces you to work harder because it’s heavier, then I believe you could still hold that higher power on the nicer bike by just changing to a harder gear.
But 300w is not 300w, it does depend on the inertia in the system - put enough in and there’s no way you’re going to manage to carry on putting out 300w (can you do the same watts on a 14% uphill as 14% downhill?)
It is only a very minimal part of the demands, and possibly not the limiter that really needs changing, but it certainly changes the specificness of the training if the speeds are very different.
Yes, true. In the same way that 300w on a high inertia trainer is not quite the same as 300w on a low inertia trainer. They are different in terms of muscle recruitment etc. But to that end, I’d think that would further support using the better bike, as you are using the muscle patterns that you are more likely to end up racing on, no?
I think other factors would be more significant than whether youre on a winter or summer bike in terms of benefits that translate on race day, unless you are racing in winter of course.
Not least the desire to ride; so if the heavier, mudguarded, more comfortable winter bike gets you “out there” go with it, or if thats a turn off to training use the race bike.
Fair points
I am commuting on a mountain bike with heavy knobbly tyres. Getting it up to an acceptable speed makes me work hard, don’t think that I would be putting out as many watts if I was on a road bike going slightly faster. I will probably be more likely to keep the commuting up in the bad weather with the sturdier tyres so that’s another positive.
Interesting post about run training speed liked by Alan Couzins and lots of Joe Skipper posts.
Not sure if it should go here…
The key words are “most” and “easy”
The thread in general was worth a read, skipper aside (who contradicts hinself at least once) all the fast runners ran “slow” long/easy runs. Its not rocket science but was definitely Tinpot worthy reading.
I love the casual replies, oh I run 1.45 marathon and I train at 12 min miles…
So much flexing
it’s a kind of reverse willy waving…
There’s some people out there that think the easy run pace of elites should be scaled up for novices. So if your 6min/mile marathon runner runs mostly easy at 8:30, (+41%) then an 10min/mile marathoner should be running mostly at 14min/miles, not 12:30. An interesting rationalisation but with no physiological reasons to back it up.
It’s such a shame that Tin Pot used evidence based decisions and relied on science rather than tweets, he would’ve been a much better human if he’d reversed that position.
A good point about scaling. There were a few comments in there relating to weekly distance and that the recommendation doesn’t always hold if you ‘only’ run 70km per week.
Some said to do easy runs based on RPE not a scaled percentage of race pace. Makes sense to me.
As a guess the ideal is to do your running at paces which will benefit the target physiology but for efficiency weekly average pace/distance should just about trash the legs without getting injured. Then have recovery weeks to reset.
it’s the wrong question to ask…
It depends on an individuals physiology, where their first threshold is, its not as easy as saying you should run 2.30mins slower than MP , for some those figures will be much closer than others.
Yeah, chucking numbers out there like that is just nonsense
That Tinpot fella would have listened to evidence , read the science and still done it his way 
Seriously just following “the science” isnt always best, as science is usually looking at why something happens and scientific beliefs change as scientists learn more.
Look at Counsilmans work on lift and propulsion in swimming, he had theories that eventually were disproven, but only because propulsion wasnt generated in the way he believed, with lift created via sculling motions; the Bernoulli principle. The dominant force was drag. He was almost right, but totally wrong! (If that makes sense)