I was interested tonight to see that the 18:09 Marylebone to Bicester North (1N53) was not the usual six-car 172s but was formed of 172 101+102+165 025. Although it makes sense to have some compatibility between an operator's sets, I had assumed that the different transmissions and performance characteristics would mean that 172/165 combinations would be unlikely. Surely the superior acceleration of the 172 would potentially cause damage to the 165 transmission by dragging it faster than it's programmed to go? Any thoughts from those with better engineering knowledge than I?