I've had similar results though never done a "scientific" test. I have a couple of wheelsets with different tires that I use for different conditions. The faster tires usually reward me with -1:30 to -2:00 minute times (sometimes a little more) on a 23 to 24 minute lap of technical but rather flat xc singletrack.
This is not at race pace however, just good fast fun riding pace.
I suppose the results may tighten up if I were to give it an all out effort on the "slow" tires. I believe the gap may tighten because of the traction limitations of the "fast" tires.
I may have to try this...

 

What tires are you running on the Hei Hei?

 

Forekaster V2 29x2.6 on the front and Rekon Race 29x2.35 on the rear.

 

Ikons, and even EhLines but lesser, are always syrening me to pedal harder and grab a higher gear. Even though I already did that twice in the last half mile.

I've only got anecdote.

But there is a clear advantage. Rekon (not race) was slooooooooow.

 

Wow, that's almost as much as an advantage as trading in an obsolete 27.5 bike for a shiny new 29er.

 

27.5 is obsolete this week?

runs to check bikes

Phew. Only the good wheel size in our fleet.

 

I love my 27.5 bikes. Why? Because I own them. I shall defend their honor until they are sold.

 

Can easily be 5-10%

Bicycle Rolling Resistance | Rolling Resistance Tests

Bicycle Rolling Resistance publishes detailed reviews and articles about mountain bike and road bike tires, which have been tested on our rolling resistance roller

www.bicyclerollingresistance.com

 

A fast rolling XC tire can easily cut several minutes off a 50 minute ride, but I would expect more honestly. That 8.14 miles in 51:27 is like 9.5 mph and in 49:24 is like 9.9 mph. Although I guess it depends pretty significantly on the trail, IE a lot of stop and go type tech and corner braking before climbs can drop average speeds pretty dramatically.

 

Lots of navigating rock features at (relativly) slow speed, lots of turns and braking. Constantly accelerating out of corners or features. The KoM averaged 12.0mph. My PR s 10.4mph. This long segment is comprised of 9 smaller segments. Of these 9 segments only 3 have parts where I run out of gearing and spin out on my single speed. I spin out around 14mph on the single speed.

 

Purely anecdotal, but to me the big difference is in how gassed I am at the end of the ride (or how far I can go before running out of steam) rather than in a quantifiable speed difference.

 

If you are competitive in your race class, this is a huge difference. Usually less than a minute for podium spread in 1.2 hr race.

 

Wow, that's almost as much as an advantage as trading in an obsolete 27.5 bike for a shiny new 29er.

Funny...my 29er is quite a bit slower (10-15%) than the 27.5 with the exact same rear tires and similar fronts. The 29er is 2 years newer, too. Wheel size is still not the end all, be all when it comes to what makes a bike perform...but keep following the marketing if you like.

I love my 27.5 bikes. Why? Because I own them. I shall defend their honor until they are sold.

I still pick the 27.5 8 out of 10 times because they're more agile and fun to ride.


...anecdotally, of course.

 

...but keep following the marketing if you like.

I was gonna anyway. But glad to know such things are approved by No!Apathy!.

 

I've had similar experiences with Specialized Fast Trak (up front) and Specialized Renegade (on rear) versus either a Maxxis Ardent Race or Recon. The Specialized tires will improve my speed a solid 10%+. However, they are extremely light and very prone to side wall wear/failure on my local trails.

The Fast Trak/Renegade is my go-to on race day but definitely not a durable tire combo for other rides.

 

2 minutes is massive for a 50 min race, probably often 5-10 finishing positions.

 

Crazy how some people will give up speed on almost every part of a ride just to have (possibly) better traction for that 1-2% where a burly tire might help. Those same people usually get smoked by better riders on "low traction tires" on even the worst conditions.

 

Okay, this just hurts.

 

I enjoy a bit of pucker.

I could* ride super meat on superer chunk at superest speeds.

Or find some mild to medium chunder and cruise on XC tires. Scaring myself sometimes on turns and chutes.

*after lots of training and coaching

 

All I know is faster patterns feel lighter on the pedals than lighter casings. I would sooner race XC with DH casing and XC pattern, than an XC casing with DH pattern.

 

Except the thinner casing actually has a bigger impact on rolling resistance than the tread itself.

Bicycle Rolling Resistance | Rolling Resistance Tests

Of particular note is that if you browse the gravel bike tests, you'll find some very slick tries at the bottom (e.g. Maxxis Re-Fuse) because of the thick casing.

 

Compound must be taken into consideration as well. The softer the compound, the slower the tire.

XC tires make a huge difference in flatter, more pedally terrain. However, there is a law of diminishing returns. I’ve done a lot of testing on one of our downhill trails (I’d rate it a blue trail). It’s got some steepish bits occasionally but overall you’ve got to pedal and pump quite a bit to stay fast.

I’m always chasing my PR on this trail, and since it’s easy for me, I’ve tried running XCish tires in hopes that I’d gain a lot of speed on the smooth pedally sections. All in all, I am consistently faster on the lower half, but slower on the upper half, because the XC tires are…scary, and I can’t trust them to hold in the corners.

My best overall time on the whole trail is with enduro class tires, on a hardtail.

In true XC conditions, a proper XC tire set can’t be beat.

 

I commute into work on a rural highway, but even driving 65 mph, I’ll get passed by folks who want to drive faster.

I’ve noticed that those same cars that pass me are often no further down the road once we get into town and there’s more traffic.

I haven’t checked their tires, but I don’t think that’s the reason they are slower in traffic.

🙄

 

I’ve been racing xc on ikons, but am going to try some (reportedly) faster rolling tires next season. I do feel confident on the ikons, tho.

 

@OP, that's a significant time difference, although I would expect more for different tread designs and weights.

How about perceived effort? Did the faster tyres feel they rewarded your effort more?

I'm usually on DH treads on enduro casings (1000-1200gr) and after reaching a certain speed it feels like there's no point pushing any harder. Not much gain for the extra effort, at least that's how it feels, but strava tends to confirm this.

 

Some of the results from those rolling resistance tests are surprising. Conti Race King XC Protection has half the rolling resistance of a Pirelli Scorpion XC Lite, weight within a few grams of each other, visually similar central tread, the Continental has taller blocks by 0.5mm, but the Continental has a 1.75mm measured center casing thickness to the Pirelli's 2.00mm. I'm not a paying member of that site, but the devil is definitely in the details.

Not to prattle on and nerd-out on this, but it's the same argument for aero for the average enthusiast vs. pros--it seems to not matter because we all go slower in comparison, but we also take longer to cover the same distance as the pros making it actually more beneficial on the clock even if we can't physically perceive anything as we ride.

 

Marginal gains and aero always matter, I fully realized this during covid when we were doing TT starts, and I got 3rd, one second behind 2nd place on a 100 minute race. We all have to arrive at some personal reasonable limit to how much money/time/effort we spend chasing marginal gains.