Hi, I Need some advice on saddle set up (height angle etc) to minimise lower back pain. Also any exercises I should be doing to strengthen my lower back.

I've had lower back problems for years due to a motocross accident. I found getting saddle height correct to be critical in curing my back pain when climbing. So much so, I had to get a gravity dropper to make sure my saddle sets back to the correct height for climbing after lowering it for technical descents.
It's trial and error to find your optimum position, but once you do, measure from the top of the saddle to the centre of the BB, the back of the saddle to the centre of the bar and the height of the bar to the floor.
If any of these measurements are out on any of my bikes, I get pain after 5 mins into a climb and numbness down my left leg after 10 mins.
And getting the saddle level on flat ground lets me use my travel adjust fork to keep it level on the climbs. That helps a lot.

My physio gave me excercises to build core muscles for support. but they were specifically to aid my particular problems.
See your GP and they may refer you for treatment which will help.

Hi there. It's a tricky one this, because it might not be the saddle that's causing the trouble..
Ideally your saddle should be flat. If you tip it either way it'll either be trying to dump you off the back or push you forward and both of these put extra strain on your back.
First off, the saddle needs to fit your ass! They're not all the same to it's a good idea to try a few. If you're not balanced on your sit bones it can cause allsorts of trouble.
You want it to be high enough so that you have a slight bend in the back of your knees when you sit on the saddle and put your heels on your pedals. It's best tried when holding onto someone or something so you don't keel over! If you cant use your leg muscles properly due to a low saddle, that will certainly cause some pain.
If you can get the saddle to a height you're happy with on ups and downs it saves a lot of messing out on the trail and is usually more comfy in the long run.
The pain might be because your core isn't strong enough for the exercise, meaning your back does more work than it should. Play with your saddle and let me know how you're getting on.
How tall are you and what bike are you riding?

Hi, thanks for your comments. I recently got a Giant Rapid 1 on CTW. Its a 55cm frame and Im approx 6'1". I normally ride my 20" Canyon full suss without any problems, but Im not used to road bikes so I figured I had something set up wrong.

Sounds like the bike is way too small to me. I am 6ft1 and have a 58cm frame and it fits me perfectly.

Agree with Obi – a 55cm frame sounds tiny esp if you ride a 20" FS. Start by getting the fit checked by someone who knows what they are doing.

Core strength and control would also be good to work on – so look at 'plank' exercises and other yoga. Its really good for building up core strength and stability without stressing anything.

+1 for the bike being small .I imagine the bars being to low which won't help your back.

http://www.cptips.com/weights.htm

I got back pain, but that was due to lack of ride fitness then I got it only on long rides, the back pain then occurred on my road bike again I was not used to the different ride position, however it was worse until I called in at a new LBS whilst who spent an hour adjusting my bike setup and position on the bike, and its been a lot better since.

I found getting saddle height correct to be critical in curing my back pain when climbing. So much so, I had to get a gravity dropper to make sure my saddle sets back to the correct height for climbing after lowering it for technical descents.
It's trial and error to find your optimum position, but once you do, measure from the top of the saddle to the centre of the BB, the back of the saddle to the centre of the bar and the height of the bar to the floor.
If any of these measurements are out on any of my bikes, I get pain after 5 mins into a climb and numbness down my left leg after 10 mins.

+ 1. Sums up my back ache when cycling…only need to be out by a few mm and my back hurts. I added an extra spacer recently under my stem and it's caused my back to hurt on long rides.

I imagine the bars being to low which won't help your back.

I know this differs from most people but I struggle to get the front low enough…high front end gives me terrible backache. Thats why I love travel adjust forks: 100mm for a nice low front end for the XC bits then 140mm for the downhill/singletrack bits.

It doesn't sound like your bike is too small, despite the above comments. Giant recommend 55.5 (large) for 6' 0" to 6' 3", so at 6' 1" you are spot on.
For what it's worth I would suggest setting the saddle level, height so leg straight (locked out) with heel on pedal at bottom of stroke. Adjust saddle on rails so boney protusion below knee is perpendicular above pedal axle when crank at quarter to nine position. This should give a good starting point to fine tune from.
To relieve your back pain I would imagine you probably need to experiment with different stem length/rise combinations.
Hope you get it sorted.

I bought a 19in frame and i'm 5ft8 (it was a deal I couldn't turn down) and I got lower back pain from riding so I swapped out the 90mm stem for a easton vice 50mm one and put some high rise free ride bars on, shifted my seat forward a few cm and hey presto, problem solved. i'm no longer stretching out to reach the handlebars, I can get more weight over the forks and maneuver around easier.

HTH

With me it is a core strength/fitness thing. I have much less pain than when I was beginning to do longer/tougher rides but still occasionally get lower back pain toward the end of a race or a particularly long ride.

It got better with riding more – I haven't done any special exercises.

I was getting lower back pain too so experimented with saddle angles. Tilting the saddle forwards a small amount fixed the problem for me. I used to get a fair bit of lower back pain but cycling seems to really help. It seems to strengthen it and keep it all moving.

Hi thanks to everyone for the feedback. Im comfortable with the bike size. Like Coleman said I was aware of Giants size recommendation for my height and it was also what my LBS recommended. Since posting last night I have dropped the saddle a couple of cm (when i checked with my heel on the pedal….well Im embarassed to say my heel didnt reach the pedal at its lowest point. I also shifted the saddle forward slightly. Ill keep fiddling till I get it right. Thanks again