i've used time atacs on both my bmx and mountain bike for nearly 20 years now. i prefer them over spds for a few reasons. 1. there's no need to adjust the tension. one tension setting is it and it's pretty much perfect. 2. the amount of side to side float is great for when you're diving through berms and avoiding rocks, roots and trees. spds don't allow that as there's little to no float. 3. they're durable. i've had no issues with the 2 sets that i have. they're both close to 20 years old and have needed no maintenance other than a new set of cleats every few years.