What is the rule of thumb for length for...
What is the rule of thumb for length for a skate ski,this will be a gift for my 23 yr old 5ft 10'' tall?
Skate skis are sized primarily on weight. There is a weight chart on this page. At 5'10" he/she is likely to be on the 192cm. The weight chart recommendation is where you should go, unless he/she is exceptionally light for his/her height and/or not very athletic. If so, you might lean towards the 187cm.