Another issue with the study: 6 weeks is not enough to induce myofibrillar hypertrophy (and whatever small amount of hyperplasia might happen, if it does), which one might expect to increase endurance performance. For a very long time, the idea of hypertrophy was debated because studies stopped before 12 weeks, when these types of gains pick up as neurological gains taper off.

I'm gonna go ahead and invoke specificity of training. For a long-distance cyclist, the benefit of lower-body strength training is questionable.

It does depend on the questions you ask, though. Lifting for endurance? Probably better off on the bike. Training to sprint? Different question. Here, it makes sense to build a base of strength, and then to do power training (explosive lifts and plyometrics) to increase power output. For a crit racer, these types of repeated bursts are useful. Riding centuries? Maybe not for you.

Endurance athletes are not force-limited. Sprinters are limited by power, which has both an energy and a time component. Just being able to put out a lot of force isn't going to cut it.

Personally, I feel that lifting has had a positive impact on my riding. Part of the issue is that only doing squats also might not be that useful; typically, the feet are angled out for balance, but no one pedals like this. I'm more a fan of deadlifts, which encourage you to drive your heel more, and one-legged squats, step-ups, and lunges (the foot is pointed forward). I'm nowhere near what an elite rider might put in, so the added volume is not detrimental.

I'd also question the way in which these guys were squatting. Most of us have had it drilled into us that we're supposed to accentuate the eccentric phase of any lift. Studies have shown lifting to increase strength only over the same ROM and at the same speeds of contraction as the activity you're training for.

So, you've eventually got to make your lifts look something like what you'd do on the bike in order for it to carry over.