Originally Posted by Carbonfiberboy

This section of the thread is quite odd. One should have realized that the "burn" is caused by one's muscles consuming carbohydrates at an increased rate: the tech is here: https://fiercetraining.net/lactic-ac...-muscles-burn/

The whole point of training is to increase the rate at which carbs are burned, i.e. producing more power. If one doesn't have a power meter, leg sensations are a good guide. You want your legs to burn. That's the whole point of training: to get stronger and faster and be able to hold higher power for longer. That requires cellular level adaptations, and we only adapt under stress. I.e. more stress is good, sought after in fact. I tell beginning riders that cycling is actually all about climbing hills, because that's where it's easy to generate more power and thus cause more muscle damage - the whole point.

So if your legs don't hurt with the 150s but do with the 170s, it's simple: you're putting out less power, not more. If you're riding along on the flat and other riders are passing you, that means you're not even going fast enough to get on their draft. If you're doing 28, you're passing everyone who's not a pro. Time to get some instrumentation. More information is better. A simple start is a Garmin and a heart rate monitor strap. You can upload the Garmin to one of several websites which save and analyze your information.

OTOH, if you are more comfortable riding shorter cranks at lower speeds and you obviously like that, continue as you are. Just try to be more aware of why you are more comfortable and be happy with that.