Basic level maintenance facilities and bike parking are available onsite at Gweek Campsite ...(just ask). Otherwise there are some bike business in Helston see links below:
Local bike hire options:
Shipyard cycles in Porthleven: 07462 411664 .
Lizard bike hire: 07951 934 604 (they also bring/collect bikes to campsite for a fee£).
Lakeside Cycles in Helston: https://lakesidecycles.co.uk/
For a Useful cycle route planner, see these websites: