Chin ups to sternum and upper arm length

[heavyiron8]

My upper arms are shorter than average, in this case, I can't touch my sternum to the chin up bar no matter how hard I try, unless I'm essentially doing half a muscle up and use momentum to do so. I'm guessing in this case, it's best to just go up to the highest point possible in the chin up ROM?

[Mark Rippetoe]

Widen your grip.

[Karl Schudt]

Getting stronger helps, too. I didn't think I could do it until I did it. I didn't change anything, but I did do lots and lots of chinups.

Accelerating hard after the "dead" portion of the chinup can help, too. Start fast off the bottom, and get yourself through the midpoint, and then pull as hard as you can up to the top.