Tire chat (nerds only)

Ok, I’ll play. 
Worst tires of the modern era?

Kenda Nevegal (V1) I’m not exactly sure how I ended up running these but I hit the ground more times than I care to admit and usually surprised by how i got there before I understood why they have the “Nevergrip” nickname. 

Circa 2010 Conti Mountain King - Less grip than the Nevegal and the knobs fell off if you even thought about riding anything rocky. 

I’m on 100% Maxxis currently. These days I’ll run an Assegai when appropriate but I’m still pretty partial to a DHF/DHR setup and have a soft spot in my heart for a HighRoller 2 but judging by available options history seems to have passed that tire by. Have been on a bit of an XC/DC fling this year and have found the Rekon to be an excellent all a-rounder.

Inserts across all of my bikes. Running a mix of CC Pro, CC XC and Tannus. I think the Tannus inserts offer the best blend of weight, feel/traction and puncture performance than CC. Not as confidence inspiring as CC if you have to run flat but they get the job done. Tire pressures vary depending on what bike I’m riding and where I’m riding it but overall things have been trending lower as I explore the limits of running inserts. I’m a big rider in rocky terrain and at the bargier/more aggressive end of the 40+ spectrum so we’re talking 23/24.5 on the lower end. 

General setup across bikes. Tire size can vary between 2.35-2.5

Enduro and Ebike - Tannus f/r DH casing/MaxTerra rear, DD/Maxgrip front 

Trail Bike - CC XC F/R DD/Maxterra rear, Exo + or DD/Max whatever front

XC Bike - CC XC/Exo/MaxTerra F/R 

DH Bike - CC Pro/DH/Maxgrip F/R 

This is  good topic I don't think gets enough attention. I'm slowly gathering data on it but its going to take a while to test everything!

A few things I've noticed -

Tyres are spring, and air pressure changes the spring rate but they are not an air spring! ie the gas pressure doesn't increase much when they compress. The casing construction being energised by that pressure is what turns them in to a "spring"

Pressure + width affects the contact patch and pressure + casing changes the spring rate so these 2 need to be balanced to get the best performance

Like suspension, (actually it IS suspension) there is an optimum rate for everybody, so I think there is a window of width & casing that each person "should" run (I hate talking in terms of right & wrong) and trying to run a tyre lighter or narrower than that will severely compromise performance.

Inserts - I've flip flopped a bit on these, I think in a similar way to volume spacers in suspension they have a place but aren't a substitute for the appropriate spring & damping. The ideal compound & casing should be the same regardless of whether an insert is in there or not, particular for general grip and small bumps, but they might still be useful in rough terrain by adding damping to the system.

AXS pressure recommendations - I've had pretty good luck with it the couple of times I tried it. Like anything though these are always a starting point, but tyres have such a wide range of factors its really nice to have something to work from!

Weight - I would be interested to see people try "light" tyres but add the weight back on to the rims and see what happens. I think the perceived benefit (if there is one) more often comes from less hysteresis and rolling resistance in the casing than the reduction in weight.

Oh and I forgot about nevergrips! They were horrific. I think Kenda scored a great deal on speccing them as OEM on everything for as season or 2 so everybody had a bike that came with them at that time

I like this thread as I’m a big tire nerd.

test idea for vital- test loop (timed climb and descent) on:

enduro bike with enduro tires 

enduro bike with xc tires

xc bike with xc tires 

Xc bike with enduro tires 

id love to know where speed % comes from.  Use a power meter to equalize climbing effort. 
 

The biggest factor affecting speed on a MTB (climbing and on the flats) is the tires.
Not the bike weight or suspension travel. 
Most modern bikes are efficient enough that if you're seated the whole time, the rolling speed difference between a 100mm race bike and 160mm trail bike, given the same tires and wheels will be about the same, given the same power output. 
If the trail is very steep up or down, you will see the lighter bike pull a little time back on the climb and the enduro rig pull back time on the descent. 
It's very easy to play with this if you have two bikes. Put your 1400g carbon wheels and fast XC race tires onto your 160 or 170mm enduro rig and be blown away by how fast it is everywhere but on a steep loose downhills (where you need braking traction). 

The rolling resistance between a set of DD Maxxis MaxxGrip Assegais and a Maxxis Rekon Race tires in Maxxspeed compound is likely close to 80-100w at 15mph. 100w is generally difference in FTP between an elite XC racer and an average rider. 

Agree. I’ve been running xc tires- schwalbe wicked wills- on my stumpy EVO.

id just like to see numbers to confirm 

Honestly I was nervous switching from Maxxis to Conti Kyrptotal on my Enduro/park bike because i pedal the first couple of laps up the hill before the lift/shuttle opens.
The Conti's in Supersoft/Dh casing roll much better than the Maxxis MGrip/DH casing 

The conti's in Supersoft dont feel as soft as the maxxgrip however that doesnt feel like the case on trail, they perform much the same with the contis feeling better as IMO The excellent job on the casing makes them lighter and for whatever reason give a better carcass feel.

I Can run about 2 psi lower with the contis before the carcass/grip falls away(from over rolling or debeading etc)

The maxxis casings are good, But they weigh alot - I believe we have along way to go in Tyres/tires

In my opinion an underrated part of tyre talk is matching tyre and wheel stiffness, soft tyres and stiff rims means burping and ripping off carcases, as the tyre moves and deforms but the rim tracks true in the terrain. Stiff tyres flexy rims means lack of grip. Its about finding the balance.

The PB review of the new Berd wheels is an interesting one, for a long time I've thought wheels are too stiff, and that we are trying to "out strengthen" the common issues of dents, burping etc. Making a wheel/tyre combo stiffer and stiffer isn't a solution, its about building compliance in so they can move and deflect to harsh impacts.

Yup there is definitely a case for matching stiffness to tyres as well as front/rear! Would mean we kind of need several different rim options and/or spoke counts, as opposed to the one-sized fits all state of wheels right now but there is a lot of performance to be had there. One of the nice side effect of mullet configurations is reducing the relative stiffness of the front wheel without needing to change any of the other parameters too!

I also think a lot of tyres are too square for 30mm rims, the new conti's have such a square tread, it only slows you down on climbs, I personally favour a rounder profile, gives better grip when cornering, maximizing traction when the bike is perfectly upright isn't a priority

I used to care about weight and rolling resistance, but now I'm 100% on Maxxis DH MaxxGrip Assegai/DHR on my enduro and e-bike. The downside is the rear tire lasts for like a month or two max on the eeb, so I'm tempted to try out the Maxxis bikepark tires (I think they're basically DH MaxxTerras with a wire bead? has anyone tried them?), or the Schwalbe bikeparks too, but they're nominally not TLR, probably bead shape and whatnot, which is holding me back.

Awesome to read through this. Some points i wanted to piggyback off of:

- Tires are the variable that affects rolling speed above all else these days. Purchasing a Transition Spur at the start of the year confirmed this for me. Started by running Wicked Will Soft/Speedgrip and was blown away by the rolling speed compared to my "enduro" bike (Ibis Ripmo AF), however when i threw on Tacky Chan UltraSofts a month ago, the bike lost a lot of pep. Still incredibly fun and capable, but my goal of rolling speed was entirely realized by the tire choice, and less so the frame kinematics.

- @TheSuspensionLabNZ , great perspectives, I would go a step further and say that a pressurized tire system is a spring AND damper. Softer rubber compounds and thicker carcass construction aids in trail dampening by slowing down compressions. The pressurized tire (spring portion) also does some of this heavy lifting, but anyone with a blown suspension damper will know that these systems work together to improve your ride. Just as racers turn to heavily damped suspension setups for performance, they also opt for thicker carcass and ultra soft rubber for dampening (even though protection and grip are the typically desired performance gains).

- As for inserts, while I can understand and have experienced the benefits, the same riding characteristics can be achieved through proper casing selection and pressure. As for negatives, tire inserts can act as a tire lever and force the tire bead off the rim in cornering scenarios. This happens more frequently with hookless rims and certain insert designs as a result of their cross sectional geometry. 
The argument that inserts allow riders to ride back to their car if they get a flat is flawed as well. Checking sealant and proper casing/inflation pressure will eliminate the vast majority of punctures.
The Schwalbe MTB product manager explained it best on other sites podcast #204 about the Tacky Chan:
1. The additional weight of inserts could be more effectively used in carcass construction to yield better rim protection, support, puncture protection, etc.
2. If teams are modifying tires or turning to inserts to function correctly, tire engineers have not created a good enough tire (or it is being used for a purpose outside of it's intended scope).

Happy to keep this conversation rolling,

I’m not confident I can service Conti DH casings in the field (can barely seat them at home). This has become a big speedbump in my intended journey away from Maxxis (and magic Mary). 
 

I finally mounted up Kryptotal F / R. I really love them while going straight, they’re fast and just feel fantastic. They brake really well. Supersoft feels hard on wet roots and in loose stuff, enough so that I got an Argotal for the front. The amount of effort it’s taken to seat it kinda renders it useless, as I don’t think I could seat one with my little pressurized canister and a floor pump (talking either on trail or at the car—these mofos seem to need a garage level compressor!)…

Kryptotal Front did ride square: I felt the side knobs grabbing and climbing out of ruts…rear is great, I’m almost unconcerned with rear tires lol

i only ride dd/DH casings and e-bikes. 

Yup, the damping part is also super important! I could kind of go on for days about tyres, but the damping is an interesting part because it is part of what generates grip too. Rubber is viscoelastic so has 2 modes of generating grip - the first is your regular mechanical friction between the surfaces, but the second is hysteretic grip which is where the rubber deforming sideways creates an opposing force in the material as it squishes. This is the "damping" part, and kind of similar to how a  damper resists compression forces in a shock. So a bit of movement/slip in the tyres is what generates the highest amount of grip when turning.

Another place you can see this sometimes is if you have a rubber strap wrench on a shock air can - if its super tight you can feel the strap will often skid a tiny bit and then all of a sudden feel like its glued to the metal and you get really good purchase on it. That would be that property coming in to play!

It interesting that the krypotal tyres have been coming up - its one of the tyres I've measured on the dyno recently and could see it behaved different to the schwalbe & maxxis tyres I had tested before. Noticeably stiffer but also slightly more damping too! It had similar tyre rates at 2-3psi lower pressures than a maxxis DH compound.

This also reminded me of a long time ago when they ran the Red Bull Downtown race in Portugal  - it was on very smooth, worn down cobbles and many people tried slick tyres like the maxxis hookworm but found it was terrible! I don't know if they tested pressures much but everyone ended up using regular DH tyres like the high roller or minion and I think the main reason for it was the "squirming" of the knobs was just enough to build friction in the corners. 

Tacky Chan Super Trail would probably be up your alley if you want a precise tread with minimal/no transition knobs and a supportive casing that still pedals fast.

Hey if you can't keep going on in the Tire Nerd Forum, where else can you chat about this stuff? haha.

Great explanation on the 2 modes of grip generation in tires. I've used the scientific white lie that tread = mechanical grip, rubber = hysteresis grip, but alas, it's never as easy as that (we can't forget about the casing). Though it's a decent enough approximation to communicate the different types of grip a tire generates.

I haven't spent enough time on the new Conti tires to notice a massive benefit when compared to the likes of UltraSoft. If you care to share, what kind of dyno assembly are you using? 

Funny thing, I just ordered a power meter today (an Aliexpress Xcadey that was discounted to only 200 €, apparently works quite well). Mostly to find out how many damn watts I'm throwing out the windows with the Racing Line Michelins

I've got a fixture that looks like a truing stand to support a wheel by its axle, and a flat circular plat around 100mm wide that fits to the load cell of my CTW RD-2 damper dyno. So its only a simple fixture and testing by compressing in a straight line, and the size/shape of the pressing part will probably have an effect. I figure if I keep it all the same then it should give some kind of comparison to work with.

I have a 27.5" front wheel I've been testing everything on, (also the maxxis distro had a clearout on 27.5" tyres so I could get a range of casings in the same tread pattern way cheaper than I would have otherwise!) but the conti was actually 29" and I wasn't sure if that would make much difference,, so seeing several people comment on those in particular in a way that correlates is pretty interesting!

Feel like winching up a fire road and swapping 5 sets of tyres for us, for science!

I have a perfect 5 minute strava segment climb in mind. Execution wise I think spring sounds good as it might start snowing soon over here. Might make sense to do a benchmark run in cold temperatures to see the influence on rolling resistance though... 

I very very occasionally ride in snow (Hobart local here, so once or twice its cold enough) but I've got friends in PNW that rave about certain rubber and tyre combos for cold weather riding (in particular the Michelins become rock hard (iirc?) around freezing).

I wonder if there is any noticeable change in tyre warmup so to speak, I know from suspension that for the first 30seconds of a run, your damper comparatively sucks until it gets to operating temp (note it takes continuous bouncing on the bike for 45-60s to adequeatly warm up a damper before a DH run)

Thats 5 sets of tyres and at least 5 different pressures each, thank you

I think you'll need to add one of these to your setup with the power meter. 

https://vo2master.com/product/analyzer/

Rather than a climb test, is there not a roll down test that will better answer these questions? 

In skiing they do a glide test. Wax a ski, take to from a dead stop and see how quickly it will glide a set distance. 

https://swixracing.us/nordic/pdf/swix-test-protocol-for-testing-of-glid…

I did consider this as well, a roll test could be more efficient if you can mitigate the change in wind resistance from body position.

Look in to the "chung method" or virtual elevation - if followed correctly it can account for things like wind resistance and elevation change. You need to follow the exact same track though and not use your brakes but its been proven to be quite accurate. It will also be factoring suspension movement in to the rolling resistance measurements but as long as you don't change that it should still be pretty good.

You only need a power meter and speed sensor but it is quite clever with how it works - basically rolling drag increases linearly with speed but aero drag is exponential, so knowing those 2 things and using a simple power equation the program will work out the coefficients that are the best fit for your ride data. 

I started going down a whole new rabbit hole using tire prep and a durometer to test rubber hardness. There's a handful of treatments out there that can change the compound dramatically.  The Hot Lap2 softens the rubber a few points, but also keeps the tire rubber from drying out.  The acidity in different types of dirt change the hardness the second the fresh tire touches it. This treatment can give you a fresh feeling tire for longer. Butttt, the more you use it, the more the rubber does get soft.  When the knobs get too soft, you feel them squirm on hardpack, you don't feel it on loam.  Heres some photos on my DH bike.

That’s rad- where did you buy the spray bottle?  I’m only seejng it in gallon jugs.

Edit JEGS has it : https://www.jegs.com/i/Pro-Blend/509/5306040/10002/-1?gad_source=1&gcli…

I’ve never seen that before, interesting!