Touching on the deadlift and squat topics together in one fell swoop…
Personal recommendation here would be to keep all “tools” in the “tool-box” (both in terms of exercise selection and variation [which includes range of motion]) and work to find what is best for you over time, rather than what is best for a cyclist right now.
One condition (a principle to live by, really) to get out of the way: if you do too much, too soon, too fast — or any combination of these approaches — you will likely get substantially hurt.
However, if you incrementally and conservatively learn an exercise and load it appropriately, you can feel pretty safe at least dabbling with just about any movement. Now, any exercise can be counterproductive and lead to some minor issues (pain/discomfort/etc) if it is the wrong fit for the individual, even when the dosing is “right”. But, this takes time to learn about yourself as an athlete.
For example, I am a strength coach by trade and have been strength-training for 10-15 years. Now, approaching 30 years old, I am finding that axial-loading (loading on the spine) on the shoulders with my posture in combination with the bike leads to back pain; Back Squats crush my SI joints on the bike (because I am compressing on a significantly arched/lordodic lower back and anteriorly/forward tilted pelvis); Front Squats crush my upper back on the bike (because the front load exaggerates the kyphosis of my T-Spine).
I could spend hours treating the symptoms through recovery modalities, or I could just choose a better fit for me — Zercher Squats and Single-Leg variations of the Squat and Deadlift — in order to avoid the symptoms altogether. It just took some time to learn about myself, my body, and my response to training to figure this out. Granted, I do this for a living, so the learning curve wasn’t as steep. But, seeking out resources as you go through the training process is a great way to support this kind of learning!
In terms of Range of Motion, I would similarly encourage anyone to take stock of where you are as a cyclist and strength-trainee. Are you a novice lifter with < 1 year of structured strength-training experience? If so, there is a TON of value to performing quality, full-range reps of Squats and other movements, and a lot of the adaptations can still carry to cycling at that point. Are you a recreational cyclist like me? I would think a similar approach could be justified, but hell, so could experimenting with different ranges of motion — why not, we are just rec’ athletes! If you are an elite athlete or somebody with much more lifting experience, concerning yourself with “transfer of training” becomes more important. Transfer of strength and power gains in the weight room tend to come from focusing on joint angles, planes of motion, and velocities that match the demands of the sport. A partial squat could potentially be more beneficial in this regard. But again, I would definitely encourage doing a self-inventory of what your priorities are and where you can get the most value from your time spent “under the bar”.
Hope this helps!