Have done imperial centuries on my current three bikes. The Tandem and MTB have been offroad and the Giant SCR and the MTB have been on the road. Can't compare the three bikes as the routes are different but If it was a road ride- then the Giant with no suspension, thin saddle and harsh aluminium frame has been the easiest on the body. Then again- On or Offroad- I would not give up my Thudbuster Suspension post and wide saddle on the Tandem.
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How long was I in the army? Five foot seven.
Spike Milligan