Do Strathpuffer first – then Relentless seems a lot less daunting 😉
More usefully (maybe) – I’ve done relentless a few times – some random musings…
It’s varied from a stunning sunny day and starry night to pissing rain for 24h. As with anywhere in the UK, it’s variable. It’s not been too cold on any of the occasions – positive single figures degC so when dry, very comfortable. In the wet – minging! You’re unlikely to see snow.
The Nevis range cafe stays open all night so you’ve got a warm place to grab a coffee if that’s tempting.
Camping is very limited if that’s what you’re planning. You’ll likely be pitching in the car park (gravelly surface) so plan accordingly.
Darkness – not puffer levels of dark – but you’re going to be using lights (and head torch off the bike) for a good chunk of the night. That’s probably the hardest bit for me.