PeteHski

Yeah I think it's just common sense. There was a discussion on the TrainerRoad podcast last year where this very point came up. Some guy was having trouble getting their bike fit dialled in (usual aches and pains) and one of the coaches mentioned that a lot of guys would be a lot less sensitive to minor fit variations if they focused more on their own mobility and strength limitations. Lower back pain is often associated with lack of core strength and flexibility.

Not to say bike fit should be ignored, but it shouldn't need to be hyper sensitive - at least in relation to basic comfort. Obviously if your fit was horrendous it would cause problems anyway, but otherwise shouldn't be a problem with a half-reasonable fit. Having put in the effort to do a regular (and varied) core fitness program I find that I can hop on pretty much any bike with the saddle set in my ball-park height range and ride without falling apart! The longer the ride, the more critical bike fit tends to become, but 90 mins is not that long really. For me it's 5 hours into a ride when I start to notice if there are any fit issues. It's all about conditioning.