Grip size is a tough one to recommend. Some people like slim grips, while others prefer a super thick grip. Whatever we feel could be 'right' for you, doesn't necessarily mean you can't use another size.
Following is a brief guide in our words, what we would recommend for whom and why. Still not decided? Then buy an extra set of sleeves in an alternate size. Try them both and return the grip sleeve you decide against keeping(we'll refund a used grip sleeve within 30 days so long as there is not excessive wear or crash damage).
Match your current grip size
A great place to start is by considering your existing grips. Do you like the shape and size of your current grips? If so, try and match the thickness like-for-like, or perhaps you'd like a grip slightly thicker or slightly slimmer. RevGrips started compiling a list of grip thicknessesHEREto help. Remember, because Revgrips isolate your hands from vibrations, you'll gain comfort while using what feels like a normal grip. In other words, there's no need to over-compensate for comfort with a thick and padded grip. Therefore, we encourage you to go for the grip thickness you like the feel of, over and above what you think you should be getting for comfort.
What glove size do you wear?
Going small improves the feeling and control you have over the bike. But the smaller you go, the less padding you have. This is also relative because if you wear an XXL glove, a small 31mm grip will be too small to get proper purchase around.
Likewise, if you only wear a medium glove, the large 34mm sleeve will likely be too big. As previously mentioned, this isn't set in stone as whatever feels right to you, is fine. As a very rough guide, if you wear an XS or S gloves, you'll be best on a small grip. If you wear XXL gloves or bigger, you'll be best on a large grip. The rest is all a bit blurred. XL gloved hands will find Large grips comfy, but to offer the best control when really pushing hard on extended and rough descents, a medium grip will possibly be best.
Fit for purpose
Very generically, this is another way to guide you. Hit the bike parks and like getting air time? Get a slim grip to offer the most feeling and control, such as the 31mm Half Waffle. Mile munching all weekend long with your weight resting on your palms most of the time? Size up, the large could be ideal. If you like mixing up your riding and do a bit of everything, go for our best seller...the medium 32.5mm