I’m currently looking out for 2nd hand fork bargains to go with my new frame. Being used forks the steerer tube has usually been cut down, I know the headtube length on the frame is approx 135mm, how much extra do I need to add to this to find the overall steerer tube length I need?

Hope this makes sense.
Thanks in advance.

50 to 80mm, more if you like a few spacers under the stem.

Cheers ton. Most of the forks I’ve been at have around 190-200mm steerers. Which fits in with your figures. Don’t really know if I need spacers or not. My current bike has 100mm travel forks and hardtail frame and has spacers. My new frame is full suss and I’m looking at fitting 140-150mm forks, so don’t know because of the changes in geometry between bikes I need spacers.

Stay a average headset stack height being 30mm(unless your frame is inset) and most stems being 40mm deep. You need about around 70mm on top of your 135mm to be safe.