stretching out forwards can very much help the lower back ime as well. When I first saw your photos, I knew right away that too much reach wasnt the issue, and actually thought that going forward could help. Without knowing where your seat is positioned on the rails, if it is in the middlish position, an easy way to experiment with stretching out your body a bit to see if it helps with lower back is to move the seat back a small amount, maybe a cm or so, and also at the same time rotate your bars slightly forward, which will bring the hoods slightly forward (your bars seem to have been rotated back a bit towards you).

My suggestion for this type of stuff is to ride with the needed allen keys and take a ride where you have time to make slight adjustments as you go along. Ie, keep it as is at the start of ride, then stop after 10-15 mins or whatever, make a slight adjustment of seat back and/or bar rotate, and you'll immediately feel if the change feels better or not. Until you get your adjustable stem on, at least this way you can see if slight changes help, costs nothing.

also, as Machka mentioned, small seat angle changes can help a bit too, although I personally find a level seat to be more comfortable than angled back like her and some others. Again, do changes one at a time and feel the difference. Doing while riding and taking breaks for changes to me is the best way, because you will immediately feel the changes and imo this helps better to properly evaluate if it is better or not. If a change is not good, you'll probably know in a min or two, so take your time and tweak as you go.

as you have gathered by now, getting your bike so it fits well is very personal, in the end you have to take the time and try stuff and be attentive. An allen key or two, taking the time, making small adjustments and just paying attention is the way to go.

I like my bars 2" hight than my seat. I do not use the drops very often. Fine tuning bike setup can take a while.

In the bike fitting forum I ran across a post that help me a great deal.

It was about posture on the bike. As suggested, I made an effort to flatten my back (and make it straight) by rotating my butt a bit forward, kinda like a little scoot. It helped with a pain that was only in my right shoulder and I can ride most any ass hatchet that I perch on. A simple fix for two problems.

For a completely different take on back pain and the solution: I've been riding fix gears as winter/city/rain bikes forever. Always used road frames. The components just go from one frame to the next. (Those bikes used to live hard lives, Bad things happened to the frames.). Setup #4 was a large touring Miyata with a very long/high headset and shortish top tube. I slammed the 13cm Cinelli 1A stem. The first 5 years I suffered up hill. Couldn't breath deeply causing anaerobic pain early in rides and my lower back really wasn't happy. So I took a wild gamble. I had a local framebuilder make me a 180ch stem. An early ride with that stem was 75miles and some real hills. Hard! Tiring! No back pain!

I am aging and my stems are coming up and back, but slowly. 20 years and many bikes and stems later, my stems are 175cm -5 degree, 155cm -5 degree, 135 Cinelli 1A near slammed on a short head tube frame, 130 Nitto Pearl (140 in anybody else's book) on a long top tube custom and a 120 -17 on another long top tube custom. My back and body love all these bikes.

Edit: I forgot the mantra I came up with when I went to that first 180 stem. The cat stretch. Ever watch a cat do the stretch were it makes it's back really long with a bit of sag? I don't actually do that, but my back can relate.

Ben

Did the longer stem fix your back? and how much longer was it?

azza, eyeballing the stem on your bike, it looks like it might be 100mm, not a lot longer. What is its length?
Like I said, try moving your seat back a bit, plus rotating your bars forward, and you will increase your reach by probably a couple of cm's. Do it mid ride and at least you will see feel if it feels better for your back from getting a bit more stretch out.

stems come in a whole slew of lengths and angles, so there really are lots of options out there if you go that route, or find that the one you ordered isnt right.
I would add too that I'm sure a lot of folks are like me and have a small collection of spare stems around from changing them out on other bikes, its a fairly common thing to have to do.

My saddle is all the way backwards, my stem is 90mm and 6 degrees, I have ordered a 90mm adjustable stem, I am going for a 60km ride before work tomorrow so I will see if adjusting my handlebar angle helps tomorrow morning.

Looking at your pictures, your position is not much different from mine, and I've ridden like that for years and over long distances. But answer Machka's second question -- how flat is the Brooks?

And yes, you might need to strengthen your stomach muscles as much as anything else.

My brooks is still a bit flat, there are a few spots that have started to soften though. I do an intensive core workout twice a week so my stomach muscles are quite in pretty good shape.

if your present stem is 90mm , the 90mm adjustable can move the bars up a bit, but it will also move the bars back towards you. Same length, angle more upwards= closer to you.

good luck experimenting with diff changes.

also, the tilting the seat back a smidge trick can change the feeling for your back and pressure on hands, but it really depends on your bar height and how ye ol cajones feel about X amount of upwards tilt of the front of the seat.

Your stem seems much too short and high to me already. More back angle is better for your back because that substitutes flexion for compression in the spine. Just because you're touring is no reason to adopt an uncomfortable position. Cycling is very good back exercise. That said, you might need more specific exercises to create a stronger core. Consider buying a copy of Core Advantage.

This is what it's supposed to look like:
https://www.youtube.com/watch?v=z04uoO7U_SA
https://www.bikeforums.net/road-cycli...l#post12953035
https://www.bikeforums.net/long-dista...l#post12207030

There has to be a 110 you could borrow and see how it feels. His bars are level with his seat, so not high at all. We aren't talking racing here. I tend to agree that he really does try a longer stem, given that his seat is already all the way back.

it did help a lot, especially on seated climbs on the trails
went from a very short stem about 50mm to about 90
wiggle has some Deda stems on sale now at $22US

your riding posture looks fairly good, you may want to consider a 120mm stem instead of the adjustable, since your seat is already all the way back

also the saddle slid backwards will rotate your hips forward activating your front leg muscles more, but to counter this change in position, you could be pulling back on your bars and putting tension on your lower back

on long climbs, I usually slide back on the saddle, and hold on to the flats of the bars since i don't need brakes during climbing, if I had to get to the hoods, it would likely stretch me out too much

I would add azza that if you are going to change stems on your own, read up on how to do it so you don't damage the star nut inside the fork. The bolt on top of the fork threads into the star nut down inside the fork tube. A local store can show you how to do it properly, especially if you buy a new stem from them. Is pretty basic but it always good to see vis behindhand

Just a thought before you start changing stems. Reach should not be adjusted by moving your saddle fore and aft. First set your saddle height so that you have a 25-30 degree bend in the knee at the bottom of your pedal stroke. Next, adjust the fore and aft position of your saddle by dropping a plumb line from just below your kneecap to the center of the pedal spindle when the crankarm is at the 3:00 position. Now you are ready to adjust your stem length. It is just a guess but from the pictures, and having your saddle all the way back, you are not positioned correctly in relation to your pedals.

I have gone onto aliexpress.com and found a few cheap carbon(hopefully to reduce road noise a little bit) stems 120mm and 110mm in varying angles, which should I go for and at what angle? my current stem is 90mm at 8 degrees

I've had the same symptoms since I was about your age. I've learned how to deal with it now to the extent that I can usually ride pain free all day. For me, I'm convinced my back muscles carry tension in them without me usually being aware of it. Riding hard makes it worse. But that's frustrating because I want to be able to do just that.

My most important thing has been to pay close attention to the feeling and become aware of it before it becomes pain. Figure out how to make that feeling go away now. Concentrate on relaxing your back. Try to drop your belly low and make that your default position.

I think yoga helps both physically and by improving awareness. Keep a full range of motion so your body can ease into the right riding posture. Exercise helps build stamina. But also manage the tension and don't let it become self feeding.

Don't pull on the bars a lot. Do that only for little bursts.

For what it's worth, I'd recommend staying away from carbon, if from inexperience or a mistake, over torquing bolts can frack stuff up. Just less one thing to worry about.

And there really are no bike shops nearby that you can go to? Us online guessers are only so much of a help.

I have a torque wrench so I should be ok

Righto. As someone who has stupidly snapped seat post bolts before, I wanted to put out the warning. Plus ALU ones are cheap, but it's your money.
Have fun experimenting. Small deliberate changes often bring great reward, sounds like a proverb or something.

$.02 raise your saddle 1/4"-1/2" and learn to rotate your pelvis down a bit more, flatten your back and bring your chest more forward so your head sits 1/2" back with a smidge more bend in the elbows. Instead of sitting flat on the seat with a slightly bowed back flatten/ lengthen your back. Your lower back looks bowed a bit instead of a dynamic bridge to your shoulders. Also get off the bike and stretch but see what you can do to make your spine long.

can you explain your visual of dropping the belly low? I also practice yoga twice a week to strengthen the core and to remain nimble. My yoga training helps to keep my core stable, however usually my belly is sucked in a bit. As my instructor illustrates, pulling the belly button in towards he spine. The yoga practice and specifically that visual has helped to alleviate my back pains and riding posture quite a bit.

my suggestion since this is obviously a serious issue for you and biking is a passion as well, is to take yourself and bike to a LBS. You will pay more, but they may have a few stems you can try, assuming you buy one. In the end you will have a professional assessment, a quality product, and a relationship with the LBS. I, myself can only provide 2 cent comments, and not a seasoned shop keep.

Unfortunately where I live, I only have one LBS if I can even call it that, I have tried getting issued solved with them before but they are really not helpful, and I also already spoke to them about getting a new stem, the only stems they have were the ones already on bikes, he did say he could order one in for me if I wanted though.

ahh, so different than most of us then that live in cities where there are loads of options of stores and loads of options of cheap, ready available stems of diff lengths and angles in stores to look at and eyeball with your bike beside you.