Sooo, I realise now that by making transfers for Ronde van Vlaanderen, I am no longer in the purist league
I was assuming all stages of the Spring Classics would have unlimited transfers. Seems odd to allow unlimited transfers for some races within this series but not all. Each is an individual race and I think you should be able to transfer players in and out just like the pro teams do.
The purist league was the only one I was focussing on and now I'm not in it! Oh well.