I’ve been off the bike for around a year now due to persistent hip/groin pain when riding. I also notice it when walking up steep hills. The medics diagnosed cam impingement, but it started almost 3 years ago, not long after I had a significant foot injury. I recently discovered that due to that injury my RoM on that ankle is massively less than the other side which got me thinking. How important is ankle RoM when cycling?
On a related note, is it worth trying shorter cranks? I am 6ft and have 172.5mm cranks on my road bike, but was fine with 165mm on my fixie (obviously I don’t want to ride that while injured). I’m happy to pay for a bike fit (especially with a fitter who will really think about my foot issues), but I’m assuming I should wait until I’ve given my new stretching regime a chance to work.
The leg is one big, long kinetic chain……and very often when you have pain in one area, the root cause is located in another area completely.
You often see this in runners who have lower leg issues (Achilles strains, ITBS, etc) and the root cause is weak glutes.
I would think getting a fit would be worth the investment, but make sure it is with a really good fitter who will understand the potential impact of your lack of ankle ROM.
Just to throw it out there - could you have also ended up with a leg length discrepancy or a change in q-factor, due to your ankle injury?
Agree that this is a case where a good fitter should be able to help, and also maybe a physio who knows about cycling.
I think my leg length is OK, and the fit on my bike was pretty good before I hurt my foot. I’ve seen 2 different physios, but neither are cycling specific, then again given the pain is not just on the bike but also when walking (especially uphill), I don’t know that cycling specific is necessary.
I think the best I can hope for is that a fit resulting in shorter cranks would hide my hip issue and mean I can ride again. That’s better than nothing.
A shorter crank may help, but you would only be adressing the symptoms, not the (potential) root cause. I would recommend finding a good sports-oriented physical therapist to help work on your ankle range of motion. In addition to relieving pain on the bike, it sounds like it will help make a lifestyle improvement as well.
I think someone with knowledge about cycling would be good, because of the way the hip is fixated by the saddle when riding. Walking or running, you can probably compensate for lack of mobility somewhere with extra movement elsewhere (might not be great but will work), but on the bike the hip joint is oriented in a specific way and needs to take a lot of strain.
I’ve got a smashed ankle that is now very stiff and has about 60% range of movement. It means my knee shoots outwards at the top of the stroke and my hip soon gets sore.
I have found q rings help a lot, I think it is because the force is applied differently to round rings.
A bike fitter also put 2 × 2mm pedal spindle washers on which has helped alignment of my knee more. Cleats are as far to the instep side of foot as possible.
This.
I have found this to be good advice in general for most riders. A LOT of people could benefit by moving their cleats back.
I hadn’t thought to change the cleat position alone because when the foot is in the bike shoe, it is better than any other shoe I own! It does make sense to experiment, and cleat position changes are free. 
My cleats are in the middle of the adjustment range, though the shoes are Specialized and I think they tend to be further forward than some. I’ll draw around the cleats as they are now and try putting them all the way back next time I ride. I’ll do it then so I remember to adjust the saddle height too!
My fitter tells me your foot should remain relatively fixed position through the pedal stroke. So, in general it shouldn’t be a problem, but it may be causing an affect because there is ankle movement or attempted ankle movement.
One of my ankles isn’t perfect after a bad accident and doesnt have the same rom or strength as the other side. Can tell the difference when kicking hard in swimming but haven’t actually thought about in years, so no difference in cycling. It’s not as bad as yours though, as I had good physio straight after as a kid and its been much longer since it happened.
If you’re moving your foot a lot in the pedal stroke, you may have a saddle too high and need to make a conscious effort to not move your feet (think shuffling your feet on carpet as a kid in socks to create static). Can’t refute any of the advice given above, my cleats are as far back as they go, not because of the ankle but I could see it helping.