Does anyone know the capacity of a Shimano Tiagra rear mech. Will be undertaking my first Dartmoor Classic 100 mile in two weeks and i'm looking for lower gears for a bit of a safety buffer..
Currently have a compact chainset and a 28t largest rear cog which is fine for the 60-70 mile rides i have been doing recently around Dartmoor but i would really like a couple of lower gears to give me a bit of breathing room on some of the steeper climbs on the route (especially as most of my training rides take in one or two of the steep / long climbs used for the Classic and i'm nervous about tackling them all in one ride!)
Have a spare 34t MTB cassette and a longer chain, any reason this won't work. I'm guessing i will have to avoid big-big gear combinations.