Wander, as long as the sum of (rentals + final sale) inclusive of VAT is more than 25% of the original purchase price inclusive of VAT, you can word it any way you like.
In my model for basic tax rate payer, the total paid is £465 + VAT (£558 inc VAT), if your are the employer, you can rent out the bike for nothing, and sell the bike at the end for £465 + VAT or a set any arbitrary rental and charge the difference at the end, for example, if you want the final sale to be £208.33 + VAT (£250 inc VAT), then set the rentals amount to £558 - £250 = £308 inc VAT in the hire contract.
As I said, as long as the end user pays in total more than 25% of the original price, there is no problem with HMRC.
In my model for basic tax rate payer, the total paid is £465 + VAT (£558 inc VAT), if your are the employer, you can rent out the bike for nothing, and sell the bike at the end for £465 + VAT or a set any arbitrary rental and charge the difference at the end, for example, if you want the final sale to be £208.33 + VAT (£250 inc VAT), then set the rentals amount to £558 - £250 = £308 inc VAT in the hire contract.
As I said, as long as the end user pays in total more than 25% of the original price, there is no problem with HMRC.