I haven’t ridden the 2.2 in the front but briefly tried the 2.35. It didn’t give me much confidence in loose over hard surfaces, so I swapped it out for a Forekaster (the old one) and put the Ikon on the back. I liked the 2.25 Rekon on the front better than the 2.35 Ikon. YMMV of course. This is all dependent on your skill level and where you ride.
What do you plan to ride?
Alps
Dylan posted yesterday some test results on IG with Aspen 2.4 and Race King 2.2 on a gravel road.
Very interesting. The difference between fastest and slowest configuration is 7s on a 5min out and back road. He reports that he held a constant power output. I hope he will post some more data points and add some Chung method tests to this.
I’ve done over 100 laps on a 14 minute trail looking at tires, clothes, and all sorts of stuff. All I can say is that he’s gonna need a lot more laps!
Has anyone following this thread used the Chung method (virtual elevation) for testing MTB tyres and equipment? I’ve had success using that method for testing cyclocross tyres, on a local grass field, with good repeatability, which has allowed me to tease out rolling resistance changes. I also look at the BRR testing, and do my own roller testing, but I think everyone here accepts that drum testing or roller testing only gives us one element of rolling resistance (the tyre hysteresis losses only).
I’ve been wanting to try something similar for my XC bike. For a XC type of trail though, it’s more tricky. I don’t have any quiet loops around here that that are suitable. Any braking, due to corners or other riders, screw up the Chung method analysis. So I think I need a quiet, flat loop with gentle corners where I can ride a consistent line, but that’s really tricky to find close to me.
The alternative, which is what I guess most people do, is just ride a typical MTB trail and try to hold their average power constant. I’ve never got particularly repeatable results doing that though, but in the absence of anything better, perhaps that’s the best protocol there is.
I’m able to average the same power for a 14 minute off road loop on most runs. +/- 1 watt at most and the times vary by a fair bit.
I’ve done the same on a simple climb and was unable to “for sure” tell the difference between “normal” and “normal plus a 10 pound back pack”…which should be super easy to differentiate.
I’ve found the variablity is such that one or two runs in two different setups isn’t nearly enough…and that’s the kind of thing you see on youtube all of the time.
It’s way harder than I thought it would be.
Joe
Thanks Joe. That’s been my experience too using similar methods, although I’m not entirely sure why. Perhaps it’s small differences in line choice or variability in wind conditions, run to run. Tyre temperature could be a source of the variability too, because even a few degrees of tyre temperature change can alter the suppleness of the rubber. These are the kinds of things that are well known difficulties for people testing aero mods for road and time trial bikes (including me) and perhaps they affect MTB testing too, although probably to a lesser extent for MTBs for some of those things.
I’m convinced that if enough repeats were done, ideally in an ABAB type way, then that could overcome the variability that occurs, to find the ‘right’ answer though the average values. However, that amount of testing quickly gets rather tedious!
Looks like he deleted the post but why he thinks that result is interesting?
Speedkings are expected to be a little bit faster rolling than aspens and results show the same.
The narrow wet weather Maxxis Severe is in the process of being released:
It can get tedious, that’s for sure. And minor line changes probably matter too…although enough runs and you get pretty consistent.
As for aerodynamics…I did these 7 runs (6 “good” runs) alternating between skin suit and baggies and got these results. Not much time between runs, just enough to throw on the baggies over the suit or vice versa. I’m calling it “probably 15 seconds faster” but I wouldn’t mind more runs to confirm it. For one minute per hour in a race, it’s totally worth it if it’s true.
Joe
That’s a good result, and a rigorous test there, with those 7 back-to-back runs. The difference is much more significant than the variability, so in cases like these we can be fairly confident in the results.
Interestingly, your 1 minute saving for a 1-hour race is consistent with the savings that Specialized concluded in this video, where they tested baggies versus tight fitting lycra. They measured the aero benefit to be equivalent to 70 seconds over 20km distance, which sounds quite similar to your result. That’s equivalent to about a 10% drag coefficient saving, which is around 4-7 Watts at 12-15 mph based on some quick calculations.
I’ll resist the urge to talk more about aerodynamics though (as tempting as it is, because I’m an aerodynamicist by profession), at least not in this tire thread. I guess the point is that for fairly big changes and by doing a lot of repeats, the performance differences can be measured quite reliably using the method of timed runs targeting a constant average power.
Nick
Since this thread is still ongoing I took the freedom of removing ‘2021’ in the title. carry on.
So what’s everybody’s favorite do-it-all XC tire these days?
My race bike (SS hardtail) has Rekon Race 2.4 front and 2.3 rear, which works great for my local races (as long as it’s dry). I’m looking for something for my FS bike which does more trail riding, with the odd marathon race thrown in. Currently running Forekaster 2.35 front and Ikon 2.35 rear. That combo has worked ok, but wondering if there’s something better these days?
For Maxxis I really like 2.4WT Rekons F/R for general trail duty. Not the fastest but very noticeably faster than the DHF/Dissectors I run on my big trail bike.
Currently trying 2.35 Ground Controls in T7 F/R on my epic evo for non-racing, but am not overly happy with them right now, they don’t feel like they hook up as I’d like them to.
I run some combination of Aspen and Rekon Race on the Epic Evo for racing. currently Aspen F/R and very happy.
Agreed, 2.4 Rekon for me too. Also tried Ground Control and didn’t love.
I run 2.35 Ikons front and rear for marathon races and general trail riding (I ride a Spur). I’m very happy with the Ikons. Looking to try something faster rolling for certain races, but I like the 2.35 Ikons in most situations here (Front Range CO).
So essentially no difference?
Good to know about the GCs, as they were on my short list.
Probably will end up with Rekon 2.4 front and either an Ikon or Rekon Race rear. Unless somebody has a better idea. I used to run an Ikon front as well, and that was fine for racing, but I didn’t love it at the end of long days when I was tired and my bike handling starts to get sloppy. And I’m not doing a second wheelset for this bike (since I mostly race the SS).
I’ve had good luck with the mezcal 2.35 for all purpose use around front range. Fairly new here though, so I’ve only got 40-500 miles on that
Mezcals are garbage, if you race in the M30-39 age class in the midwest, you should never run these tires, they are slow, prone to puncture, you should run DHR and DHF if you are in that age group here in the midwest, especially at the lutsen 99er.
*Mezcal 2.35s are my go to now, throw a barzo on the front when it is wet or the trails dry out and get the loose over hard going.
