Bike fit and lower back pain advice

Ultimately it is worth a bike fit if you're getting pain on the bike, but I'd make some changes myself first to see what happens. Fitters will vary a lot in quality, so it's not as simple as get bike fit - problem solved.

There are facebook and reddit groups (or even here) where you can post a vid and get advice - usually worth as much as you have paid for it, but they are useful at identifying things that might be obviously wrong. 

I do have some back issues but they are all off the bike, so haven't dealt with that particular one. My back generally feels great when I'm sitting on my arse.

Lower back pain is classically a sign that your saddle is too high.

Road bikes are inherently bad for your back hyperflexing your cervical spine and flattening your lumbar curve.  The flatening of the curve leads to pain

Significantly higher bars is the answer

The service that you are looking for sits somewhere between a physio and a bike fitter. There are plenty out there who can lay legitimate claim to both qualifications so I would be looking for that range of skills so they can suitably assess your position, taking into account your existing issues, and make suggestions to better enable your return to cycling. 

The International Bike Fitting Institute website has a finder tool that would be a useful start. The site also covers what they are trying to achieve in terms of regularising the services and training of fitters.

yer road biking makes this sort of thing more noticeable.. plus its way more dangerous.. sell the road bike, buy a real bike

in all seriousness, i can attest to issues on my road bike which i'm sure a fitter would've spotted a mile off, something i never would have thought off, was my saddle, it wasn't allowing my pelvis to rotate forwards... loads of pain in my hands and lower back...Still working on lower back pain on my Top Fuel, suspect its the stack height, it's getting better over time and tweaks

Someone like Rich Salisbury at Pedal Precision would be worth travelling for. Bike fitting and rehab background, he was one of my (brilliant!) students a long time ago and I would highly recommend:

https://pedalprecision.com/about_us/

Sorry, but there is no one solution, and through experience I can confirm it's not as simple as 'road bikes are bad' 🙄 

A recent example, I've been really enjoying blatting about on the road bike, typically shorter/harder midweek rides mucking about chasing segments and average speeds etc. I can happily spend a significant portion of my time in the drops or in my best impression of an aero tuck, both traditionally thought of as bad positions for back pain, but have no issues at all. Similarly my last cyclocross race (an hour of low cadence, high torque wrestling through the mud, often in the drops) or hard sessions on the turbo can leave me in zero pain.

BUT two things I've battled with are comfort on easy zone two rides, which I typically do on my more upright winter bike. And recently I had to ignominiously retire halfway round a long distance gravel event due to back pain, on my gravel bike this time which again, is more upright than my road bike.

So what is the common factor for me? Muscle recruitment. When I'm going hard or pushing on I clearly recruit my glutes more, which in turn must relax or unload the low back muscles somehow. On the long distance gravel event I was consciously pacing myself on climbs so despite sitting up, on the tops, and twiddling a low gear, I think I wasn't recruiting my glutes enough and ended up somehow fatiguing my low back.

It's really complicated to be honest, I wouldn't throw a vast amount of money at bike fit straight away other than to check you've not got anything fundamentally wrong (and you might as well just watch some Youtube videos, Road Cycling Academy (RCA) have a very good bike fitter who produces some great videos).

Because my back used to hurt a lot I also avoid things like deadlifts or squats, which often brought on spasms. However my physio taught me this was as much a psychological/guarding mechanism thing where my back pre-emptively went into spasm because it associated certain movements and postures as trouble. Learning to relax the back muscles (breathing exercises) and gently exposing them to these movements has been a revelation. So also has b simple core work, especially on the TVA. It seems counterintuitive that a wee muscle that feels like it just wraps around under your belly, and if anything pulls the low back into more flexion, can help with low back pain, but it really does.