Head angle

Yes, but I wouldn't change it just for that.  It's not like slacker is always better, it's a choice.

I don't think much has changed in the last 5 years.  I recently swapped a 2007 bike for a modern trail bike, that was a big change - but 2018? That's still modern, IMO.  You can still get modern bikes with 65 degree HAs it's not like it's obselete.

Probably not. And if a lot of your riding is along rather than down, it's not necessarily going to make a big difference to the ride. Similarly with the descending, is it steep techy madness or rolling single-track with the occasional feature?

 If the rest of the numbers remain the same (With the exception of wheelbase), would you notice a 1° change in head angle?

Yes absolutely.

I regularly used to fit angle adjust headsets to bikes of that vintage.

Superstar do an excellent -2deg one, if your frame isn't integrated headset or anything.

63.5deg is great for enduro-ing.

I don't think I would. My 2019 Enduro is about 65degs head angle I think, and its not the head angle that's holding me back TBH.

In a back to back test, probably yes.

Realistically is it going to be make or break, probably not. It's still well within the spectrum of normal.

I think we call 160/150 & 65.5deg "trail" this year. Which of course makes it no worse a bike than it was 5 years ago.

And (and this is both a subjective opinion and probably a bit of liking and adapting what you have) actually a nice sweet spot for enjoyment if you aren't constantly throwing yourself down steep downhill runs.

Off set bushes wont set you back too much and may get you an extra degree if you want to find out..

Depending on the terrain you usually ride, slacker isn't always better.

I think back to back it'd be noticeable but not on an isolated ride. Certainly not worth a new frame in my opinion

Are you using your enduro bike for enduro?

If yes then you would notice a difference. If its for regular "all mountain type mountain biking" then probably not.

I’ve ridden my Stumpjumper Evo (160/150) with the head angle set from 63 to 65.5 degrees.

Yes, I can feel a 1 degree difference and it does inspire confidence downhill, although this is at the expense of being more unwieldy in tight Alpine switchbacks.

I put the flip chip in my Reactor to the slack position because slack, but after 6 months I've put it back to the steeper position and it's actually much more enjoyable to ride on singletrack.

I do enduro in NE Scotland- steep downhill natural rooty and rocky trails as well as smooth trails.....

It has an integrated headset in a carbon frame. 9point8 do a system - but not compatible with Cube! Anybody know of any others?

would you notice a 1° change in head angle?

I doubt it I'm still riding a bike from 2015 which already had dated geometry at the time of release, I think the HA is probably circa 67deg(?) but with a 20mm longer than stock fork now, so maybe a shade slacker? 66.5deg (Meh) it's all irrelevant estimation once I hoist my fat arse on and load up the suspension anyway...

I do notice when I get a go on on a mates newer bike with maybe 2deg less HA, but I'd say I'm probably noticing the increased reach as much and/or appreciating a longer overall wheelbase, very few bikes change a single element of geometry in isolation.

In the context of the bikes I ride every day if I just lopped 1 degree off the HA and nothing else changed? (if that were really possible) Nope I don't think I'd actually notice, and for good or ill most people do just adapt to the geometry of a given bike, changes have to be quite extreme to actually make a bike "unrideable" IMO/IME.

Also worth noting that, if you run your stem pretty high, you may reduce reach a bit when you slacken the head angle.

Might be fine, might make a bike that already may be a little shorter than a slack modern bike even more cramped.

I remember when I first had a shot on a 27.5" wheeled bike. We were in the Cairngorms, and I swapped bikes with my pal so I could "feel the trail come alive" on a down hill section of singletrack. At the bottom of the descent, he said "What do you think?"

I replied "Your brakes have a funny bite point, the saddle is awful and the stem is too long."

"What about the wheels?"

"I didn't even notice."

It's not that old and I can remember when 65.5 was regarded as the new slack. People still managed to ride enduros on those bikes, have the courses changed so much?

People still manage to ride enduro courses on hardtails and 26 inch wheels, it doesn't mean that there are no improvements to be made.

I've put anglesets in a whole lot of frames over the years and never once regretted it. My current one (a V2 Bird Aeris) as far as I'm concerned is just plain better with it, I don't feel any downside except if you're not paying attention on a long grindy fire road and who cares about that? It gave my old Hemlock and Remedy both new lives, I kept those for years longer than I would have otherwise. Literally once of all the times I've done it, was it a significant compromise, every other time the bike was for my taste just better. (and even the compromise was better, because it got better at stuff I valued more)

I've always gone with the biggest change I could, I reckon 1 degree is still worthwhile but if it's worth assing, wholeass it. At the very least, if you don't like it you'll know why, you'll never be wondering if you made a mistake only going 1 degree, there's a bracketing thing.

Incidentally people sometimes obsess a little bit about the other effects but they're so small. You lose a little reach from the layback of the fork but you gain a little from the lowering of the front end, it's pretty much lost in the rounding. The BB will be a bawhair lower but it's the sort of change you get from changing a tyre and never worry about. And the rake and trail change but who actually understands rake and trail?

Bushings are good too but you've got to be more careful, not all frames can take them, others can only take a smaller change. And they do have the possibility of more unexpected effects as it changes where you sit in the linkage route. Some bikes won't really matter, some might have quite a big effect.