If you look at the picture of the adapter showed by Bikegang, it does what Glye is saying: a more vertical angle to the block.

The sport stem is compatible with the bags wit a 260mm high frame but not with he bags with a 300mm high frame and of course not with frame with a hard plastic handle like the old S-bag, T-bag and C-bag. But its not a big issue, because the frame of these bags can be replaced by the same size without hard plastic handle. I use a S-bag with a frame without hard plastic handle.

Note that all new Brompton bags do not have a frame with hard plastic handle (this handle was also a problem to use bags with 300mm high on the S type Brompton).

It will work with the Brompton QFCFA-400x260 frame.



It won't work with the QFCFA-400x300 or any frame with hard plastic handle like QFCFAH-400x260.