I need a chinup bar ten feet off the ground. I find the extra labor of keeping my knees bent while doing pullups works against me too much.
Blast, If you have a park near you with a kids swing set, you probably can use it for chin-ups or pull-ups. Some of them are a big too wide to grip, but your hands can usually hang on. You could also probably work out a way to hang something on the top bar to make something to grip.
The pull-ups hurt a lot more than the push-ups, but the push-ups works out are not easy either, when you get to the last sets.