Today an hour or so after a ride that wasn't too long, but included a few climbs, my resting heart rate was 120bpm. A few hours later and it's still hovering around 110bpm. Apparently this puts me in the bracket of tachycardia. I'm trying to understand what may be causing it. I'm average height 5'8", over weight, 14st 10, poor to average fitness level, I've always struggled with climbs. Mildly asthmatic, I have a stressful job and I think I consume what most would consider to be excessive levels of caffeine.
I guess all these things could play a part, but I was wondering if anyone else on here has encountered anything similar ?

I’m not medical at all, but google is not your friend here - get to the docs on Monday, they’ll refer you and probably you’ll get an ECG. In the meantime- ride your bike to relieve stress, cut down on caffeine and avoid alcohol. If it helps then sex is still good.

I've already ditched the coffee jar in favour of decaff. I guess that's a good move regardless of anything else.

Please err on the side of caution and give 111 a call. Your heart isn't something to take chances with.

Have a good rest and check when still in bed in the morning.

Even if it has eased off, give yourself a lazy day with only gentle activities and get more rest and check again on monday.

If it's still not back to normal, call your gp.

If it's back to normal, it may be worth rethinking how you go about your activities, everyday stress load, life style etc.

Colleague from work used to go on 1 - 3 hrs rides/week and commute 2 x 15 min/day and always went hard, hoping to improve his mediocre fitness level. After about a month he realised that he was actually becoming more and more tired, hr constantly elevated and struggled on any intense effort. Under some advice he backed off on intensity and changed a few things in his activity routine.

Sometimes it doesn't take much to get to a point where your body reacts in such a way. Hopefully it's just that.

Wishing you a good nights rest.

Forget what I wrote if you have non rhythmic heart beat, feel dizzy, chest pain, out of breath, swolen legs. In this case don't hesitate to get help immediately.

I'd say get to the docs asap or even the hospital. I had a high irregular rythm so went to the docs without an appointment. Hooked straight up to the ECG machine twice, then saw the doc who told me that the hospital was waiting for me and if I didn't have anyone to take me then he'd ring an ambulance.
There was talk of using a de-fib but they went for medication. All good in the end, turned out to be atrial fibrillation which is quite common in elite athletes apparently

Thanks for all the advice and guidance folks. It's down to around 95 now. Not tachycardic, but still higher than I'd prefer. Will keep an eye on everything and go to the quack if needed. Cheers.

You have to do whatever you feel is best for you
.
But if I was in your position, I think I'd be calling a medical professional for advice as a minimum.

In the summer, dehydration can play a major part in heart rhythm. I believe. I am not a medical person though and as others say - just get it checked out. The NHS would much rather you did this and made use of all the fantastic machinery they have there than wait and become an emergency. I had a bit of a heart scare when I was riding in Spain a few years ago - my heart was basically stopping every few seconds, pausing and then starting up again. I managed it during the trip by taking it easy and it gradually resolved itself. I went to my doctor when I got back and she was quite pissed off with me for not getting it checked out sooner. I went straight from her office to the nurse who did an ECG there and then which was all fine. About a week later I was at the hospital for a treadmill test which was fine again. I now know to use electrolyte tabs in my water when I am sweating in hot weather and just drink a lot more than I was doing, but I am very glad I got it checked out.

I had a similar issue a few years ago, including feeling absolutely drained too. A ride/hike that would normally take 4-6hrs depending on conditions etc took about 12 hours, with numerous stops as I couple barely walk!!! No heavy breathing etc, just completely drained. After a few hours my HR was still up around 150 and was still over 100 the following morning!
Toot sweet to the docs for tests etc, turned out to be hyperthyroidism. Definitely worth getting checked out as folks have said, even if it’s to be tested and told there’s nothing wrong etc.

95 is still officially (according to the UK charts at least) tachycardia. If I was you I'd get it checked out. Like seriously, pop past the GP or make an appointment...

So, I've seen the doc. Answered a few questions for him, but no ECG needed. He was happy that, as my RHR is now around 70-80, where it should be, it was most likely a combination of over exertion, stress, and some other factors.
I've been advised to monitor my HR, cut out caffeine, try to reduce stress levels, alter my diet in order to lose a few lbs and reconsider my exercise regime/activities. All of which I'm doing... and obviously should inform him immediately if anything changes.
So, thanks again for the advice folks.

Glad to hear you've been given the all-clear.