Darth Lefty 

For the past few months I've had a lot of pain in the ligaments of my left thumb. Nothing is broken, it all still works and doesn't grind. It hurts to put any strength through the thumb and it hurts when I put my hand down flat and put weight on it. It hurts when pushed on certain ways. So it hurts to shift my MTB and it hurts to hold the compact drops on my road bike, among other non-bike problems. It actually makes me disinclined to ride. It's the sort of injury that, in my experience, the doctor just says "sucks to be you, wait it out." I've self-diagnosed it as tendinosis.

FBinNY 

Sorry to hear that. I hope you're wrong, and this won't be a long term non healing problem for you.

Asuming that you;re wrong, and can't hurt if you're right, the best thing for it is heat and rest. When it's recovered enough pad the left grip so the grip point is away from the affected area. Or practice riding with a loose grip without wrapping the thumb under. Then, ride your bike as a 1x9, but not so long as to keep re-inflaming the injury.

FWIW - I use classic thumb shifters and it's not all that rare for me to strain the left thumb in a forced shift against cable or FD resistance. Some of those strains border on dislocation and put my left hand out of circulation for a week or so. I've learned to guard against that, but I wonder about those who constantly re-injure their left thumbs because of sticky thumbshifters.

CliffordK

You could go with a higher range rear cassette to limit the frequency of upshift/downshifts.

Di2 or electronic shifting?

fietsbob

top of the bars thumb shifters can be used like it was a faucet handle , no thumb required

The Grip shifter for my Rohloff hub could go on either side, turning in either direction ..

shelbyfv

Maybe a downtube or bar end shifter for the left?

practical

Ibuprofen is my wonder drug.

CliffordK

Within reason. Sometimes I think one just needs to break a pain cycle.

However, also keep in mind that pain is telling you something. Avoiding pain may help avoid more injury. There is also some evidence that too much NSAIDS may inhibit proper tendon healing.

corrado33

Why not do the easiest/possibly cheapest option. Grip shifters. No pressure on the thumb and cheap. I don't usually suggest grip shifters, but for something like this it's a no brainer.

Either that or get BETTER thumb shifters and lube the cable to make shifting extremely easy. It's possible.

EDIT: I had a similar injury to you except it was on my right thumb. I hyper-extended my thumb trying to take a very tight sock off... I'm not joking. Anyway, it was a royal PITA to shift for a few weeks after that, but it eventually got better. Now I'm back at 100%, thankfully.

Gresp15C

Changing to a different kind of shifter might be a thing to try.

I had kinda the opposite thing happen. I got tennis elbow in my right arm, and in my case, the grip shifter on my winter bike was really aggravating it. So I switched to a trigger shifter.

Yet another possibility is to temporarily switch both shifters to the right side. That would at least give you access to the lower gears when needed, and let you rest your left thumb. It could be a cheap friction shifter that mounts on the bar, just beyond the regular FD shifter.

cale

I have injury-related pain in my hands, particularly my left thumb. I can sympathise with the OP regarding pain. I didn't spend enough time chilling my joints regularly after the accident and recommend continued therapy if you can tolerate it. My injury was over 3 years ago and the pain persists. Hope you can get a "grip" on it. Haha

AlmostTrick

I had an accident at work last year that left me with stitches in my right thumb. Could not down shift my trigger shifter with it. I learned to remove my hand from the grip and downshift with my knuckles.

Doctor Morbius

I know how frustrating this is as I used to have very bad carpal tunnel in my wrists. My hands would get so numb I couldn't feel if I was shifting or not. I sometimes had to use the right hand to shift the front DER and vise verse. Fortunately, within the past year I've had carpal tunnel surgeries on all 3 wrists and am doing fine.

As an interim suggestion, perhaps get a 9 speed cassette that has the most useful gearing for a 1x9 setup. It seems 1x11 is all the rage on some bikes, so why not a 1x9?

Darth Lefty 

I can shift the road bike but the handlebars hurt. I can't shift the MTB but the handlebars are fine. Frustrating! Thanks for the sympathy, everyone. That's really why I posted. :-D I can figure out the fixes, just a matter if I want to pay for the parts and do the work.

digibud

Consider seeing an osteopath. My wife had painful hands that we thought were possibly ending her cycling. She was diagnosed with osteo-arthritis and this went on for nearly a year and brought on tears and caused us to cancel a long planned cycling vacation. At some point she finally went to an osteopath who manipulated her hands, pushing around tendon sheaths and after a few of these manipulations she was pretty much cured and now rides without any serious problem. We just bought two new bikes and hope to continue riding for many more years. Your symptoms sound somewhat familiar.

Looigi

I have an issue with my left thumb too, but it doesn't affect shifting as I'm using SRAM X1. One thing I did for an acquaintance with a similar thumb issue was switch her bike to a twist shifters from trigger shifters.

McStumpy

Even if just temporary, move left shifter to right side of flat bar? I have a prosthetic left hand so have controls all on right. Left thumb shifter is inverted and sits just to left of the right shifter

Darth Lefty 

@digibud thanks for the idea but this is definitely my tendons. I have joint pain sometimes in my right hand and it definitely doesn't feel the same.
@McStumpy good idea! But strangely, I feel weird about it. Sort of like if I tried it, it would be like parking in a handicap space.

avidone1

9 gears is plenty for me, but I live in flat florida. Wind is the only factor that causes me to need lower gears, but I never have to leave the chainring i'm in because both provide all the gears I need. That being said tendinitis is a very frustrating injury. I find that it takes months to heal and then recurs. I have it in my right elbow. I try to work around it, but it still lets me know it's there. I think this comes under rule #5

T Stew

My main two bikes I ride I only use the big ring gear so they are mainly 1x6 and 1x7. Of course though I don't have big hills around here. I plan on upgrading to 10 speed rear and ditching FD all together on both.

I feel your pain though, I strained my left hand a couple weeks ago and sounds similar, but different. I have problem with the thumb, but more of a squeezing action.. its hard to grip something with much force - I feel it in between my thumb and pointer finger and also a bit on the top of the hand in that area. On Thanksgiving day I moved a woodstove into my house from the garage to the hearth and placed it by myself. Weighed probably a little over 500 pounds. I think that is what did the hand in, glad I didn't strain anything else!

I haven't used a pill in at least a couple years... especially avoid NSAID unless it's absolutely necessary. For aches and pains from minor injuries the body should be able to take care of itself. The reason it often doesn't is the modern diets which aren't so good. Before resorting to pharmaceuticals, the first thing should be to address the diet.