Just signed up for this ride in a few weeks time. 55 miles with 5500ft of climbing although cyclometer is showing 8200ft of climb. Problem is i have only been out on the road bike twice this year due to family commitments and the arrival of Gixer Jnr, so i am not road fit and doubt whether i could do all the climbing.
Anyone done this ride on a MTB with skinny tyres?

Waiting to be flamed for being a weakling 😯

To be honest, the climbing may well be easier on the MTB than on a normally geared road bike. It’s a decent sized ride but you’re going to need to put SOME miles in. I’d not ridden much for 6 weeks and did a ride on Saturday a little longer than the one you’re doing and it ruined me (it was also very hot which didn’t help).

Do it on your mtb wth slicks, and rigid forks if you have them, unless you have sympathetic gearing on the road bike.

Find a hill, even slight, change to your hardest gear and then back off one, and then cycle out of the saddle, so you are spinning and having to support your weight on both pedals.

Add a few long runs and some interval runs, and you will be sorted.