Having just started commuting and fitted Skinny road tyres to my MTB i have considered going further and replacing the front 'shock' forks with rigid ones and fitting a set of full length mudguards etc etc. However my bike is clearly to big for me (mis-sold!) and is now 10 years old (but in superb nick as it's hardly been used).
I'll probably fit the mudguards but leave it at that and save for a 'proper' bike to do it on....
yes; weight, aerodynamics, lower rolling resistance and larger gears - but that all adds up to make a large difference.
I spent the last 5 years on an expensive slicked MTB with rigid forks, V-brakes etc (got it down to 23 lbs), then bought a road bike last year and...... it's much faster and weighs 19 lbs and cost half the price I spent on the mtb!
I think the advantages of a road bike have been pointed out well, but there are disadvantages. They're not great for winter riding, so if you're commuting year-round, and only have money for one good bike, an ATB will be better.
It depends on how big your wallet is. Most keen cyclists have two bikes - a winter and summer bike. The summer one is obviously the flashy road racing type.
Back in the eighties, there were roadrace bikes, tourers and the new-fangled MTBs from Calif.
Tourers traditionally had dropped bars, mudguards and racks. They had lower gearing to accomodate the extra luggage weight.
Roadrace bikes were roadrace bikes.
MTBs were 26" fat tyre 'comfort' bikes with touristy low gearing and wider flat handlebars. They were dead easy to ride.
As well as all these, the Brit kids were riding around on 26" youths sports tourers with 'cow horn' ( or better still, Moto X ) handlebars and touristy low gears. I was amoungst them in the seventies.
Some smart Alec came up with an idea of combining a sports tourer with 700C wheels with flat bars and MTB touristy gearing.
They didn't know what to call it, but it became known as the 'Hybrid'.
What some smarter Alecs have done is take a reasonably priced MTB and put road slicks on it. It has the full range of gearing for climbing the shopping mall stairs and low rolling res' tyres for whipping along with the traffic.
Apart from the 26" wheels compared to the 700C wheels of the Hybrid, I would call it a Hybrid.
I rode mine round a 100km Audax last Sunday with surprising ease. Being a converted MTB Hybrid, I wasn't expected to ride very fast but I found myself in the leading group of six riders after the last control.
I will keep my Dawes Giro 500 ( dropped bar sports tourer ) for 200km events next year.