I have this quite often converting a non-cash reward to amazon vouchers (which is the best exchange rate)
I find the bike stuff might not really be what I really want so instead buy stuff I need and save the cash then buy the actual item… Amazon seems hit and miss to me on bike stuff … so I might buy printer carts or stuff I have to buy anyway and then just use the equivalent money…
Do the same sort of thing with Nectar … OH used to save up for something like a fancy mixer or fancy juicer at say Sainsbury’s but unless its on sale its easier/better just to buy the shopping with it and then get the juicer etc. elsewhere??? (Maybe Amazon :D)