@insto - it's been steadily eroded from that high ideal unfortunately. For instance, as of Jan this year, you have to add VAT at 20% to your salary sacrifice 'payments'.
The face cost of the £1000 voucher is therefore £680 (1)
However, you also need to cough up at the end for the "fair market value" of the bike. There's a table for this - paying down a £1000 voucher over a year leaves you with a £250 liability at the end (2)
So, we're up to £930 for a £1000 bike already.
But wait - because CycleScheme take a 10% cut, any LBS which is not certifiably insane would be happy to give you the bike for £900 cash instead of £900 in fiddly paperwork.
So you've actually paid £930 for a £900 bike (although that means you've had an interest-free loan for a £30 arrangement fee, good luck finding that on the high street)
There are various dodges like extending the loan period until the bike has no intrinsic value, but that does mean technically the bike is someone else's property for half a decade (if they go bust, your bike becomes an asset of the administrators, and you probably won't be able to move jobs without settling up).
I'm not down on C2W by any means, but there's no way that it gives "half price bikes" in a million years - even for higher rate payers.
(There are issues with longer repayment periods in that if you leave half-way through, you then have to pay the balance on the bike after tax, but it still isn't yours and you'll have to find the 25% voucher cost to take possession, so it will be much more expensive than just buying the bike!)
The whole thing is a bit daft. Given what it's become, it would have been easier for the government to underwrite interest-free loans on commuter bikes or something.