BrianFox wrote:That MTB has a 34 tooth front chainring, and a 50 tooth rear for lowest gear.
Your proposed road bike has 34 teeth front and 28 teeth rear.
The ratio of the two (plus adjustment for relative diameter of the tyres) defines your lowest gear. That's ~1.8 times harder with the road bike!! In other words, a 1:10 hill on the MTB will feel like a 1:6 hill on the road bike, if you do both in bottom gear.
The MTB will be *much* easier to ride up steep hills, and your circuit looks to have plenty of those (1500m climbing in 50k is really very hilly!).
The biggest cassette you'll be able to get on the road bike is likely a 32, so it's fundamentally unable to give you the same ratios.
So you can expect your circuit to be faster but harder on the road machine. Likely a *lot* harder, unless you never use the lowest 3 or four gears on the MTB.
If you want a road bike capable of the same gear ratios as your MTB, you need a very different bike. Standard road race style bikes simply aren't provided in those ratios. As I said earlier, as a minimum, I'd recommend getting a bike with a 32 rear cassette (or getting that one changed to a 32 if your heart is set on it).
I really appreciate all the advice you and everyone on here has given me. Tomorrow I'm going to see the Trek bike in the flesh, I will put all the questions and concerns to the people at the Trek shop and hear what options I have.....
While riding my mountain I only ever recall using the lowest gears once and that was riding up my mates driveway to his condominium and to be honest it would not only be near impossible on a bike but also walking.....I managed on the bike after the 3rd attempt
and that was using the small front ring. On the ride I showed you from last week I never did drop to the small front ring and from what I can remember I was somewhere in the middle of the rear cassette on the monster long clime.
To be honest we probably won't do that route again as it was just too tough with to many hills (maybe when I get stronger......maybe