I’m primarily thinking about xc-ish tyres here, as I guess with tyres for the mega-gnar-squad reistance migh be quite noticable.

Switching between ralphs to rons to beavers I notice a difference in noise and that makes me feel like i’m noticing more drag when on tarmac, but I feel like once I’m off-road I never actually notice any difference.

I’m starting to do my normal pre-race obsess about which tyres to use prior to this w/e’s BMBS. A race in may at the same venue was a grease fest after one evening of rain. With several days of occasional downpours forecast before the BMBS, I’m thinking that grip over speed might be wise. Wish I had two wheelsets!!!

Yes; but unlike on-road there’s usually a meaningful trade off with grip.

That said I usually only swap between summer, all round and winter tyres (and fat, but that’s different) so there’s an obvious difference in resistance and grip between each tyre (and it depends on the surface). Not sure I’d be able to discern between two summer XC tyres in the dry though.

I do notice it on hard dry trails – how quickly the bike picks up speed on a DH run or the effort required on a long hard dry climb but some people make far too much of it in my opinion. I guess if you were searching for that extra bit of speed for racing it’d be good. As a general run of the mill rider I’ve given up worrying about it off-road.

Quite a bit, personally- I like a big tyre but especially on long descents it can hit the point where everything’s effort, or where a fast pedally trail starts to lose its enjoyment. I suppose I’m weird with this, I don’t really mind pedalling a slow tyre up a hill, I just resent pedalling them back down.

This is worth a look: http://www.bicyclerollingresistance.com/mtb-reviews

Yes; but unlike on-road there’s usually a meaningful trade off with grip.

But throw in skill and there is a way to get beyond the grip and make the most of it. You drop more time on the up and along than the down.

Yes – I think it is fairly noticeable.

But if I were you, I wouldn’t over-think it now – it’s only Tuesday!
Just bung on your fastest ralph/raceking/speedywhatever and then change at the last minute if needed. Or say sod it and run your fastest tyres even if a bit of the course is greasy and manage that bit for the rewards elsewhere.

You are doing what I often do, and more often that not, that only leads to running to much tread on the day.

Yak – Member
But if I were you, I wouldn’t over-think it now – it’s only Tuesday!
… You are doing what I often do, and more often that not, that only leads to running to much tread on the day.

Valid point Yak, will try to ignore tyre thoughts till Friday!

EDIT: I’m pretty much a high-priest of the over-analysing but this one is particularly focussing my mind as the Fforest fields course was my favourite of 2014&2015 (both races bone dry lovelyness) and I was super looking forward to the welsh champs earlier this year but I had a ‘mare in the thunderstorm induced slipperyness (worn out racing ralphs didnt help), was convincd it would be dry fo the national and…

should know better living in Wales!

I suppose I’m weird with this, I don’t really mind pedalling a slow tyre up a hill, I just resent pedalling them back down.

Not weird at all! Slow tyres are fine when it’s steep and you’re on the brakes much of the time but with flatter trails they just suck out all your flow because you have to pedal so much more.

Hmmm. Still leave it until Friday, or you’ll be swapping tyres more than riding your bike this week. Good luck for your race.

Yes. When I first got my Patriot I found it hard going, being 5lbs heavier than the bikes I was used to. Went tubeless on the same tyres and it became a decent my all day machine.

The Nevegal/Blue Groove combo that came with my XTC were noticeably harder going than the Fire XC Pros I replaced them with.

With tyres I think there can be a real difference but a lot can be in your head too – once it occurs to you they might be draggier/slipperier or whatever that thought can be hard to get rid of!

No, definitely not in your head.
Early last season I replaced some tubed Crossmarks with some tubeless XKings and gained 1-1.5mph ave overnight across most surfaces.

Similar story several years ago on my first bike, lost 1mph going from race kings to captains.

Do a little research on the topic, and you’ll find that some tyres that are supposed to be fast, just aren’t (see Crossmark example above).

I feel plenty of resistance, but none of it is due to my tyres…legs/lungs and fitness are the things that resist constantly…if it were only the tyres then I’d be having an awesome day!

Saying that, when I did have legs on me that worked, I never noticed any resistance whilst riding offroad, on-road was a whole different kettle of fish…

Ian fwiw I reckon it makes sod all difference. Go with the Ralphs.