trail_monkey

This isn't going to be a question like you may suspect based off the title. I started riding my rigid hardtail with Jones H bars almost exclusively as a do it all bike. I ride lots of gravel with lots of continuous hills plus rail trails and even urban commutes. Let's not forget I occasionally do sub 24 hr bikepacking events as well all on this one bike. I have experimented with short stems that are more upright and longer stems that are more forward (aero) and honestly they all feel good. I notice when I am grunting out a strong climb by spinning while seated, by the top of the hill my lower back is as exhausted as much as my legs. Is this normal for your back to get worked from hard spinning or is it being worked more than it should by being too upright? Or maybe since I switched to platforms and 510s a few months ago I am having to subconsciously pull up on the bars while I am seated and I don't realize it? I have heard that being more aero engages your quads and hams better but I have never known if that's at the expense of lightening up the load on your lumbars.

Just asking for opinions before I start switching stems and other stuff on my bike.

Facanh

I have drop bars and an upright-is position (at least compared to an aggressive road bike). On really hard offroad climbs I hold the hoods and I try to get in a "aero"-ish position because I feel like I can put the power down better (and also put weight on the front wheel). If it's a really brutal climb I can feel it in my lower back, it's nothing too bad tho.

So either it's normal or my position is wrong too.

trail_monkey

shoota 

I can't say that is normal for spinning. Now if you said your low back was hurting after a long climb overgeared at 50rpm I would say yeah it's normal. Something seems off though. I went through low back pain for a long time until I figured out that the culprit was my saddle was too far back and the front tilted too high. Put on a zero setback post and leveled out the saddle (sometimes a couple degrees nose down for certain saddles) and voila! just like that no more back pain.

trail_monkey

shoota 

I can still tell you this isn't "normal" and it's definitely a bike fit issue, possibly exacerbated by poor core strength.

trail_monkey

shoota 

Again, it's probably not related to your stem, but rather your saddle position.

trail_monkey

shoota 

That may be possible too but there's no way anyone on the internet can tell you for sure. Any given bike only has three points of contact, if you change only one of them and your problem doesn't get better it's not surprising; all three need to work together to be perfect.

trail_monkey

softreset

I recently went for a second opinion to a local fitter (after tweaking) as I've gained some weight since my fit, which was almost 4-years ago.

Ultimately we increased my full body extension about 1cm and lowered me another centimeter and that has completely relieved all back pain on longer, hillier rides for me. In my case, I was too compact when riding.

Spoonrobot 

trail_monkey

unterhausen

you can condition those lower back muscles just like any other muscle. I used to wear out my lower back on long climbs. I'm in pretty good shape now and haven't had that happen recently. It never surprises me much when it does happen. The lower back and abs are linked pretty strongly, so strengthening abs might help. I haven't really been doing any work with my abs beyond some swimming.

I feel like the position that achieves minimum back/thigh angle is the most powerful because it recruits more muscles. At least it is more powerful for me. YMMV.

trail_monkey