Looks like the OP is long gone .. anyway the OT is " 20 inch wheels and group rides " ... so having ridden with a Tri-group almost weekly (generally 20 mile hilly loop where I'm almost always the oldest ) for the last 5 years on 20" wheels when everyone else are on 700c road bikes, I'll say it can easily be done... once I took my 17lb 700c Merlin just to see how much faster I would be over my Moulton TSR-20 .. it was negligible .. so I continue to ride on 20 inch wheels with the group as the Moulton is more comfortable than the Merlin..