PeteHski

I run a compact 50/34 chainset and 11-34 cassette. So my lowest gear is 1:1. My FTP is around 300W and I currently weigh around 180 lbs. I can ride up 20%+ slopes on that setup fairly comfortably at a slow walking pace i.e. 2-3 mph. But cadence is very low at that speed, definitely not sitting and spinning! But I can keep moving without smashing myself, while guys on bigger gearing are often having to push power way above their threshold just to prevent stalling out. On an 8% slope I can climb all day at a steady pace on this gear setup. Someone will no doubt come along in a minute talking about spinning at a 1000 rpm and going nowhere, but on any slope above 10% I'm not going to be spinning at more than 80 rpm for any length of time in a 34/34 gear. The reality is more like in the low to moderate 50-70 rpm range. Just to compare, my mtb lowest gear is 30/50 and that is actually about perfect for spinning effortlessly up a 12% slope at about 5 mph. But that's a heavier FS bike with 2.35" off-road tyres. My sustained climbing power is about the same as yours i.e. 225-250W, which I can hold for a couple of hours of alpine climbing. I can push 400W for a few minutes if I really need to, but then fatigue is soon going to put a stop to that!