Asking for some bike fit help please? (long post)

A few months ago I asked a question about something and it came up that I was trying 155mm cranks. Swapped in for 175mm cranks.
It was advised that I was probably countering a different problem and that I should ask for help on here about bike fit. So, this sounds interesting as I have always been uncomfortable on a bike. Pretty fed up after a mile or two and keen to get off. I would really appreciate help, if anyone is willing to help me, I would love to cycle more.

<b>Beware</b>, this is a long post as I am trying to get all of the info in the first post. Hopefully it covers all the relevant details.

My main discomfort is sit bone pain. So bad. I have pushed through it, but it is bad so quick. In the first mile or so. I have sorted my lack of blood to legs with saddle shape also, numb feet, different shoes and socks. Hand pain has improved with the shorter cranks.
I have manned through it in the hope I get used to it, but never have. I am now 55 yo.
I was always just holding myself back from the bars as I was constantly sliding forwards. It was translated as weight on the hands, but this is how I was basically cycling:
https://imgur.com/chyGFn0

I have tried all sorts of things, but now have some time to try and work on this. Whenever I relaxed my hands, I just slid forward on the saddle. I have spoke to plenty of people before and the conversation never seemed to make sense.

I currently don’t cycle much as I am fed up being in pain. I commute 2 miles each way with a bit of a hill coming home.

THEN, at last, I got round to trying the 155mm cranks.
Suddenly, I understand what people are saying about bike fit etc etc.
NOW I understand why they were saying what they were saying.
No wonder they didn’t understand, things now make a lot more sense.
Now, suddenly I am more planted on the saddle, I can go no hands (well, my skills are not good enough but I can if I lean against the wall with my knee.) I can lower my chin to the bars and hold it at any position no problems, I am not sliding forward on the saddle.

Well, only a little. It feels suddenly like I have more strength on the pedals.
Feels like I have more pressure on the rear pedal which means I can hold myself stronger on the front pedal.
I also wonder if the longer crank was pulling me forward.

Now, I have always wanted to sit further back, almost off the saddle before. Now it is MUCH better. One of the things that seems to have helped this is raising my saddle by 20mm which has pushed my saddle a bit further back which has helped.

On the comfort side, I think the fact that my knee is now 40mm lower at its top than it was before is helping. I think possibly that I was ‘scrunching’ putting me more on my pointy bits of my sit bones ? I have recently also found that leaning more forward reduces discomfort slightly, also sort of plants me more on the pedals????

I was riding my 175mm cranks before I got the 155mm and my knee popped when pushing up a hill. It never started to heal until I swapped in the shorter cranks and it started to heal. Then I thought I would use another bike as a test bed and popped the 175s back on and it immediately popped my knee again. I am still recovering from that one.

Body measurements. In cm.

I used a spirit level for much of this. Obviously will be some slight differences, but should give an idea of ratios? Happy to measure different ways if it helps?

Foot length: 25cm
Floor to top of knee (sat with back to wall thigh horizontal with shin vertical): 52cm
Thigh. (Well, I sat my back against a wall same as with above): 56cm
Back length (sat on a crate and measured height from seat height to shoulder (a bit vague I know, but decided against top of head as neck length and head height make no difference to a bike fit? (I sat with relaxed shoulders and measured to that bone lump on the shoulder))): 65cm
Arm length. (stood in the corner shoulders against wall, arm horizontal, measured to knuckles of a closed fist as I think finger length not relevant?): 68cm
Shoulder width (I wasn’t sure how to do this one, so I just measured overall shoulder width by standing in the corner, one shoulder against the wall): 50cm

I always feel like bars are too far away and too low. I think I might have a longer torso which might take my shoulders higher and shorter arms make it worse.
(I have compared to various shaped people :) )

I currently am using a Specialized Roll frame (I wanted to try the relaxed sta as I always wanted to sit off the back of the saddle and that helped a bit.) I have some modolo dumbo bars which are super adjustable (I think currently a bit far away):
https://imgur.com/a/30w3Hsl

But the frame is too long I am sure.
My MTB is a Ragley Marley. Again, I think it is too long.
In the last year, I have bagsied a couple of other bikes. I can play with someones Raleigh CRX, a couple of other people were having a clear out and I have an old MTB steel frame to mess with and also an old Claud Butler Terino.
I am thinking with these different frames I can try different things. Someone also gave me a (I think partly broken) turbo. Which means I can set stuff up on it without worrying about changing brakes and gears etc. It still works as a simple roller.

One thing that feels like it would make sense is a road frame with straight bars and higher, but let’s see. I am very open to trying things.

Thanks.

Just book a bike fit with a proper bike-fitter.

OK, well I did try that, but they only used the bike i had which I knew was wrong.
I am posting this because it was suggested by someone on here to do so.
Over the last forty odd years, nothing has made such a difference as the shorter cranks.

OK, well I did try that, but they only used the bike i had which I knew was wrong.

That’s not a proper bike fitter then.

Go to someone who has a background in physiotherapy and the proper bike fitting rig and give your full medical history and a rundown of the things you’ve tried.

FWIW, shorter cranks is probably the next big thing in bike fit following a general realisation that the current use of 170 – 175 as standard is based mostly on “well we’ve always done it like this”.

I am not saying i won’t go for a bike fit, but I am wary of them.
He does have a background in physiotherapy, reviews were good etc etc.
I really needed a rig though in hindsight, yes. There weren’t any near me at the time.
Having considered it again many times, I am put off by all the negative comments about bike fits not working. About 50:50 with the amount of good ones would you reckon? Almost like a coin flip. If the standard process works for you, great.
I did some looking into frame geometries and it just seems that whatever the sta and hta are, they all seem to fit the same ratio of limb/torso.
Which I am not surprised, not much money in fitting someone who is not a common ratio.
Part of what this is about, seeing if I am just getting something wrong after all these years or if my ratios are different.
When I mentioned my crank lengths before on here, almost everyone said it can’t be that, it must be counteracting something else somewhere.

Just watch some of this for what a proper bike fit is like.

https://www.youtube.com/channel/UCoITk4L2KbnSHwHwwiweNEQ