Although apparently it's better to spend a few quid and get a good one if you're going down the adapter route, as some of the cheap ones have a habit of ripping your SIM slot apart or getting stuck in the handset.
Separate and disposable SIM seems like a much better plan for an handset you might well lose, it means your primary one doesn't have to go off line for several hours (or even days, if it happens at the wrong time) in the event of the loss of your 'cycling' phone.
Although apparently it's better to spend a few quid and get a good one if you're going down the adapter route, as some of the cheap ones have a habit of ripping your SIM slot apart or getting stuck in the handset.
Separate and disposable SIM seems like a much better plan for an handset you might well lose, it means your primary one doesn't have to go off line for several hours (or even days, if it happens at the wrong time) in the event of the loss of your 'cycling' phone.