Thanks @Ramsaye and @BobbyBriggs for suggestions. Will try closing them off to reasonable levels and leaving one open but I think I've done that and it still overheats. May need bypass, then.
@Timmy2wheels started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
Thanks @Ramsaye and @BobbyBriggs for suggestions. Will try closing them off to reasonable levels and leaving one open but I think I've done that and it still overheats. May need bypass, then.