Riding MTB with right sided lower back pain

Just curious if there are any other sufferers out there, I have had this pain for several years – iv been to the doctors, and physio a few times – and the only pain I get when riding is on the right side of my lower back.

It’s worse if I’m climbing for long periods however I can cope with it, it just niggles and sometimes I have to manoeuvre position. I had an MRI don’t a couple years ago and they did say it was slightly inflamed I think (can’t remember), I’m just curious to see if there are any other sufferers and get some advice on what you do to get through the pain? And what exercises helps you?

Try shorter cranks?

Stretching regularly is usually a good answer, a lot of issues stem from tightness/inflexibilty.

What’s your bike cockpit setup like? Could you go with another stem spacer or higher rise / higher back sweep bars?

Get a bike fit is the obvious solution?

IANAPhysio but from a couple of years of similar issues, fwiw –
Sharp pain or a dull ache? Constant of cyclic with pedalling? Tension that builds like a cramp or a hotspot type of pain? Could be so many things.
I had some lower back tension and odd RHS hip area discomfort that intensified with increased climbing, had it for a while and it’s receding now. I expect it was daily posture at a desk that started me down that road and daily stretches/yoga basics (only 8-10 mins but every day, sometimes repeated after a ride or before bed) have helped but not got rid of it yet. As it’s receded it’s happened in areas or stages which has made me realise there’s probably a few things all linked, not just one cause or one fix. One imbalance puts stress on other areas, muscles work more or less than they should and the pain symptoms are in an area that isn’t the root cause area, etc.
Bike fit and set up will come up although I suspect that’s the easier answer we all want, I also hoped it would be a case of checking fit rather than doing dull stretches etc. But within normal ranges many of us can cope with quite a wide range of positions on the bike if basic flexibility and core strength is adequate (and we’re not riding at extreme power output levels). My issues were there pretty much whatever bike I rode and they vary in set up. It’s a likely to be caused by the sofa, bed or desk chair as the bike. The bike may be where the imbalance shows up but “correlation isn’t causation”.
Lower back pain may be because your back is expected to do too much of the bracing/stability against the power your legs are putting out when climbing. One-sided pain may be related to imbalance in pedal stroke L-R or a postural issue in the background. The pain may be coming on due to a lack of core strength or it could be that your glutes aren’t engaging well at the start of the pedal stroke. Try climbing while really bracing the bars with your arms, a strong ring of arms and chest stabilising you to the bar; or try thinking ‘pedal from your butt’ as you climb. Things like that might give you some references that can help an expert diagnose the issues better.
One thing I can say is that a quick daily stretching or yoga pose habit (in my late 40s having done almost none for most of my life) has made a real difference to overall bike comfort on long rides and my bikes feel as if they fit more naturally. Aside from the much-reduced though still niggling hip discomfort, it’s a positive habit that I’ll stick with. My posture is better and general movement on or off the bike is more free.

+1 on stretching. Not ignoring the other issues, but, you don’t say if you warm up before rides or (sorry) how old you are.

The first question at my bike fit: do you warm up and warm down before energetic rides? No, I do not, and it shows, especially now I’m 40+. It won’t cure everything, but core strength needs maintaining. I usually get lower back pain on the last climbs of a long road ride if I’m out of shape or not taking care of self.

Most of my stretches are actually hip stretches – I have hip issues, and the muscles around there connect from lower back over hip to leg. Have a look at glute stretches/activation for cyclists.

And then yeah, working environment / sitting elsewhere, of course.

I had a bike fit and it made quite a difference to knee pain for me. I had my saddle lowered a load and it helped me.