IF of 0.87 for over 4 hours is a pretty epic ride. How do you feel post ride? Gut reaction is to up your FTP - have you tested recently?
Seeing your PMC, then tracking your recovery from the ride would help diagnose? Are you willing to share?
@alasdair 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.
IF of 0.87 for over 4 hours is a pretty epic ride. How do you feel post ride? Gut reaction is to up your FTP - have you tested recently?
Seeing your PMC, then tracking your recovery from the ride would help diagnose? Are you willing to share?