I saw someone on here 98 + section selling some Hope cranks in 150mm
That was me, but they were 155mm.
I’m 5’9 and 30” inside leg.
I had them on my enduro bike for a year, mainly for pedal clearance. Very noticeable at first. Difficult to describe the sensation but they felt very different. Not bad, just different. After 10 - 15 minutes you stopped noticing. Going back to longer cranks felt different again. If swapping bikes regularly then I stopped noticing. If it was a while going back to the enduro bike then I had to acclimatise again. Funnily though, when I had my e-bike, it also had 155mm but they weren’t noticeable. I think the power from the motor hid the disadvantages.
Pros -
Better ground clearance on long travel bike.
Easy to spin fast.
Cons -
Acclimatisation
Less torque. Had to drop two teeth on chainring.
Ultimately I sold them as I wasn’t riding the enduro bike much and going back and forward to longer cranks felt weird. Back on 165mm which is a Goldilocks length for that bike. My new XC bike came with 175mm and they are fine as well. Also have bikes with 170 and 172.5 and doubt I could identify which was fitted in a blind test. However the 10mm drop from 165 to 155 was very noticeable.
Lots of comments above saying “I’m a 175 man”. Interested to hear if those posters have tried shorter or just assuming that because that’s what older bikes always came with regardless of frame size? These days most smaller sizes come with shorter cranks.
At the end of the day, it’s all personal preference. Try them and report back.