A very nice Ribble Sportive 365 full-carbon bike, on which the owner wanted:

• Lower gears
• Water bottle & cage
• Cycling computer

The owner was confident enough and knew what he wanted, so had already bought the new parts including the 34/50 crankset to replace the existing 39/53 one, however he preferred that someone else fit them. (I have the correct greases, the use of a torque wrench, etc)

I charged £20 for this, which was the labour time, plus £3-something for a new chain pin (yes I agree, they are shockingly expensive for what they are!) which I supplied as the chain needed to be shortened due to the smaller chainrings. If you’re planning this type of swap then the front dérailleur needs to be lowered and re-indexed too.