Got a Fenix 5x which is great (I’ve not use a proper GPS unit, but the navigation on it is perfect for my purposes), but as it’s so big it can be a little painful on the rough stuff which forms most of my riding. Despite it being as tight as I can stand, its repeatedly banging on the knobbly bit on the end of my ulna, probably as I have quite skinny wrists. I’ve looked online to see if there are any straps aimed at making it more comfortable, but they all have similar shapes to the one it came with – is anyone aware of any that I should look at?

Failing that, I’m thinking I could buy a neoprene wrist guard and cut it so that the watch straps through it on either side (with a cutout for the HR) and protects the bit that’s getting bashed.

I’ve got skinny wrists and I can’t say I’ve ever noticed the problem… How about a HR strap and mount the watch on the handlebars? (As a bonus the HR readings will also be more accurate…)

I think I must just have quite knobbly wrist bones! Yeah, that is the obvious solution but it’s another chunk of cash and I’m not sure how comfy I’d find an HR strap.

HR strap would be my suggestion too. They’re not uncomfortable at all, you’ll barely notice it once it’s on.
They’re also not expensive, any that are ANT+ work with a Garmin so you can save a couple of quid if needed.

I’m not sure how comfy I’d find an HR strap

I never notice it on the bike, and only notice it when I’m running and get too sweaty and it starts to slip down. Not an issue on a bike as you’re not bouncing up and down like you do running.

As lunge says, there’s no need to get a pricy Garmin model, any Ant+ strap will do. Here’s one for 21GBP, you can probably get them even cheaper (caveat emptor: the reviews are fine, but I’ve never used this particular model):

Thanks, that’s good to know – might be the best solution

I’ve one of these on my 6, as well as protecting the watch it makes it a little more comfortable

I think the standard silicone straps are fairly bad for it. Given as they’re heavy watches, the stretch in the strap means they bounce around.

I’ve replaced mine (on a 5 plus) with a webbing strap, which I’ve found a lot more comfortable.

Is it not a standard watch strap fitting? My Vivoactive is so there was plenty of choice of replacements.

Good point, the strap is quite stretchy and I’ve been fancying a NATO strap anyway. Given that a lot of people seem to end up replacing theirs after it breaks it would be good to have a backup too!

Can you tighten it further up your arm? As an added bonus you’ll get better HR readings as bones affect the wrist based monitor. I wear mine higher up my right arm whilst doing hiit classes as more muscle on right arm, and further away from bone.
Too late now, but this is the reason for fr series. A lot lighter with same features (945xt)

Saw a photo with a fenix mounted to the bars with this, coupled with a HR strap? https://www.halfords.com/cycling/cycling-technology/cycle-computer-gps-mounts/garmin-handlebar-mount-kit-431612.html

Halfords do a Any+/Bluetooth HRM strap for 20 quid. Works well.

As lunge says, there’s no need to get a pricy Garmin model, any Ant+ strap will do. Here’s one for 21GBP, you can probably get them even cheaper (caveat emptor: the reviews are fine, but I’ve never used this particular model):

I would avoid buying from Coospoo on Amazon. The seller actively contacts purchasers and bribes them to remove bad reviews. I have reported them to Amazon for this previously.

I bought an optical arm based heart rate monitor from them last year. It was absolutely useless and did not give remotely consistant readings. I sent it back for a refund and left a 1 star review explaining my experience and the problems. A week after the refund They then sent me a message saying that they would send me another heart rate monitor for free if I updated my review.

They sent me a free heart rate monitor. It was a chest strap and a totally different type to the optical arm band one ordered.

I updated my review by adding additional lines saying they had got in touch and sent me a free heart monitor of a different type which appeared to work. I added a star but left all of my original comments.

They got very annoyed and sent several ranting messages asking me to delete my review and being quite impolite.

I’ve been thinking about your question. I have a couple of watches that I can’t wear when I ride. They’re too heavy, so on faster, rougher trails they hurt my wrist bones too much.

I wonder if a Velcro watch strap would help? I remember wearing ones branded Animal years ago.

A bit like this: