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Hi all, up until recently ive been riding 2.3 tyres , specialized butcher grid if it matters. I had no problems with that tyre, but it wore out so i needed a new tyre, had a look on line and all everyone had in stock was 2.6 butcher grids, si went for one of those.
Now ive had a few rides on the 2.6 butcher, and i didnt like it, initially i couldnt put my finger on it, but now i think what im experiencing is tyre squirm on berms and compressions.
I havent read anything bad about these size tyres ( unlike the plus size tyres where lots of people criticise them for being squirmy), so what gives? Anyone else tried 2.6 tyres and found them squirmy?
Tyre pressure is the same as i used to run on the old tyres, dont really want to go harder as then ill start to pinball of rocks.
What rim you running, sometimes wider tyres on narrow rims don't feel great. I'm running 3" on a wide rim at 15 psi and it feels great.
I've just gone from a 2.3 Butcher Grid to a 2.6 Butcher grid on 29 wheels. 29mm internal width.
The old 2.3 Butcher grid was 1100g - beefy sidewalls. Also quite a square profile on my rim which you could really feel bite on berms when you lean the bike.
The 2.6 is about 950g - so I think they have made the carcass less bomb proof. I prefer the 2.6 as the 2.3 felt too narrow and gave my little confidence on wet roots - but it definitely lacks the "on rails" feeling of the narrower version. I am not sure squirmy is the word I would use. It's a smidge under 2.5 too...so don't think it is even that wide!
Akira, my thoughts too, narrow rim with wide tyre not a great combo.
Its on a 27mm inside diameter rim. Im not buying new rims, so ill swap it back to a 2.3 when this wears out, which will be years away now, as i have a new capra arriving this week.
I find the slightly bigger tyres have to been run harder if you want to hit corners hard, as they just fold and roll otherwise.
The only time they tend to work for me is with the heavier duty casing which means stiffer sidewalls. Otherwise they just feel like a soggy mess.
I find the slightly bigger tyres have to been run harder if you want to hit corners hard, as they just fold and roll otherwise.
The only time they tend to work for me is with the heavier duty casing which means stiffer sidewalls. Otherwise they just feel like a soggy mess.
Yeah thats what im experiencing, but i dont really think i hit corners especially hard. Oh well, time to ditch the 2.6 then.
I reckon you’ve put your finger on it with weight. If the 2.6 is lighter than the 2.3 despite being bigger then the carcass is not as solid which will affect any tendency to tuck under.
I wouldn’t have said 2.6 was excessive for a 29mm ID rim. Plus and Fat are much more pressure sensitive than regular so it may be that you can improve the feeling to you by playing with pressure in small changes. A good gauge is pretty much essential if you want this to be repeatable unless your thumb has truly remarkable muscle memory!
Tyre pressure is the same as i used to run on the old tyres, dont really want to go harder as then ill start to pinball of rocks.
Yeah thats what im experiencing, but i dont really think i hit corners especially hard. Oh well, time to ditch the 2.6 then.
You're gonna bin a tyre without actually trying a few extra psi in there, instead going by what people on a forum say?....
You’re gonna bin a tyre without actually trying a few extra psi in there, instead going by what people on a forum say?….
It'd be interesting, in a Supersize Me sort of way, to live your life entirely on the basis of advice from the STW forum. From coffee to relationships via tyre choice, relocation advice, car selection and bike geometry. What could possibly go wrong?
I'll do it, if someone'll stump up for the expense...
With these new-fangled Wide Trail 2.6 the pressures have to be just right, too little and they are squirmy and too much makes bouncy.
You’re gonna bin a tyre without actually trying a few extra psi in there, instead going by what people on a forum say?…
Just a figure of speech, I'll probably try some more air in them before I bin them, but I'm sceptical it will improve everything, it will probably stop the squirming, but with more air I expect to be pinballed around on rocks.
The reality is that they will probably end up staying on the bike , but only because the bike they're fitted to is about to get relegated to the position of spare bike once the new bike arrives .
It was a really disconcerting feeling the squirming around on landings and berms. Initially I thought that the damping cartridge in the forks had failed. It's surprising because the tyres themselves dont really look substantially larger than the old 2.3's I was running - Maybe its nothing to do with the size, but everything to do with the change to the 'gripton' compound and other changes in the construction of the tyre - who knows.
Possibly tyre construction, as you say, I used to use spesh tyres, the butcher were always a bit hard and plasticky, a bit shite on wet roots, mibbe the new wider gripton ones are a bit too thin in the sidewall.
Based on the ideal gas law, bigger tyres (volume) means lower pressure. This then means that any variation in pressure is much more pronounced: 1psi difference on a 23c road tyre inflated to 100psi is going to be unnoticable whereas 1psi difference on a 12psi plus tyre is the difference between OK and pogoing or squirming.
Get a good pressure gauge, one that can deal with at least 0.5psi changes and is consistent.
It’d be interesting, in a Supersize Me sort of way, to live your life entirely on the basis of advice from the STW forum. From coffee to relationships via tyre choice, relocation advice, car selection and bike geometry. What could possibly go wrong?
I’ll do it, if someone’ll stump up for the expense…
Think a fair few people do that already judging by the number of utter ***** on here
Whitestone +1.
I suspect since your pressures are the same as your 2.3s, what you're actually experiencing is skitshness due to too much pressure.
You won't know unless you experiment.
Ok , so one says put more air in, another says take some out.
So far, so stw.
Thanks all
Without knowing your weight it's a bit hard to say whether you should have more or less air in the tyre.
For standard MTB tyres I've found the Stans formula of (weight in stone * 2) then -1psi for the front and + 2psi for the rear to be about right, this gives values 25 & 28psi. For plus tyres (3" front, 2.8" rear) I'm a lot less, 12-13psi front, 16-18psi rear.
So for 2.6" tyres I'd be looking at a starting point of about 18psi on the front and 20psi on the rear. Somewhere in that region, then ride and adjust until I got where I wanted and there was little or no squirming and no pogoing.
As a plus tyre user, I'm with Whitestone and scienceofficer on this, in that I suspect that by running the same pressure as your 2.3, the footprint of the tyre is now shorter and wider than previous or what's ideal. Although it's only 0.3 bigger, the 2.6 has approx 25% more volume, therefore look at making a similar percentage reduction in pressure and give it another try.
Not sure if this has been said. Make sure you have an accurate tyre pressure gauge, with some its a lottery
Ok , so one says put more air in, another says take some out.
So far, so stw.
Surprisingly however, a skills course has not yet been suggested. 😀
gas laws and such dictate it should be lower pressure as whitestone and science officer but that is assuming thetyre takes the same profile which would dictate a wider rim
However on the same width rim a wider tyre will squirm more as its more of an O shape and less of an inverted U shape so is less stable needing higher pressures to have the same stability on the rim
the only answer is suck it and see.
Wide tyres, supple sidewalls need wider rims or they will do just what you have described.
I wouldn't use less than 40mm if I wanted to take advantage of the compliance of lower pressures.
Plus as suggested get a trials pressure gauge too.
I saw these on one of the new Stumpys in my LBS and thought they looked rather small for 2.6” - as there was a tape measure on the counter I checked if my eyes were deceiving me. Fractionally under 60mm or just under 2.4” wide.
That was on a fairly wide rim, maybe 30mm (just checked - 29mm according to their website).
The High Roller 2 2.4 on the front of my hardtail measures 61mm wide on a 25.5mm rim.
So I’m blaming the flimsy casing rather than the tyre actually being voluminous!
What have gas laws got to do with it? Tyre internal volume will stay practically the same as the tyre compresses. The bike is held up by the sidewall/bead area pulling on the rim in a different direction in the squished bit at the bottom of the tyre, That times the carcass tension. The carcass tension will be higher for a fat tyre at the same pressure. So you can have lower pressure and get the same support as the tyre squishes.
Well that is a rough analysis, the more one thinks about it the more complicated it gets. But Boyles law doesn't seem to have a role.
What have gas laws got to do with it?
Because PV = K so if V(olume) is 25% or whatever greater then P(ressure) has to reduce. This is what provides the internal tension.
Other than buying another tyre with a different construction, pressure is the one variable we can control and that's dependent on volume.
I'm running these 2.6 tyres at the moment (Hillbilly front, Butcher rear). Although, as noted previously, the tread width is nowhere near 2.6, they are a much higher volume tyre than, say, a Conti or Maxis 2.4. They are also a very supple tyre though. What I've found that means in practice is that I'm running slightly more pressure than before (before being with a "true" 2.4 tyre with a sturdier carcass). This has meant that the extra pressure gives more support when cornering hard, so the tyre doesn't squirm. At the same time because the carcass is pretty supple it will still deform enough on roots and stuff to give good grip. I do worry that I will take them somewhere rocky and they'll get cut to shreds, but I've not tried that yet. Oh, and I use a pressure gauge, before anyone asks.
@whitestone - Because PV = K so if V(olume) is 25% or whatever greater then P(ressure) has to reduce. This is what provides the internal tension.
Other than buying another tyre with a different construction, pressure is the one variable we can control and that’s dependent on volume.
Well, how does that explain why you need less P when you have more V in order to hold the bike up and for it to ride nice? A fuller equation is PV=nRT where n is the number of air molecules (in moles) and R is the ideal gas constant. All it tells us is that *if* we fill our tyres up with the same amount of air each time then, for a fatter tyre we will end up with less pressure in it. I don't think anyone pumps their tyres up by counting the number of pump strokes they use, we all decide what pressure we want and keep on pumping until we get there.
Rereading and ignoring the arguments and gas law deniers, I wouldn’t be surprised if the 2.6 in question isn’t just crap.
If it’s lighter than the 2.3 as earlier is already a bad sign, but the whole point of the wider tyre is that it should be running a lower pressure than the skinnier one. If it’s apparently feeling squirmy and baggy while running the same pressure it’s just a crap design. Under those conditions it should have become (relatively) an unyielding rock of a tyre, pinging off everything and impossible to hold a line with.
Many of the early gen Plus tyres were spoiled by manufacturers getting scared about weight and cutting back in the carcass in a misguided attempt to reduce weight. Possibly this is also the case here?
I like how they ride. Plenty of grip compared to equivalent Maxxis and the extra volume improves ride quality a bit too. My only concern is that they won't be very durable but I've not had any problems so far.
greyspoke
...I don’t think anyone pumps their tyres up by counting the number of pump strokes they use...
☺️☺️☺️☺️☺️☺️☺️
I scratch the required number of strokes needed onto any pump I attach to a bike.
greyspoke
…I don’t think anyone pumps their tyres up by counting the number of pump strokes they use…
I scratch the required number of strokes needed onto any pump I attach to a bike.
That is organised. Is it the same number for each bike?
Cool!
I didn't know STW had its own flat earthers.
Cool!
I didn’t know STW had its own flat earthers.
Hello, though not sure you are referring to me.
Anyhow, how do you think a tyre holds a bike up, and how does the ideal gas law figure in that? Other than relating the pressure, volume, temperature and amount of gas in the tyre to each other of course.
Pity - I was looking at the 2.6 butcher grid - I thought the carcasses were supposed to be relatively supportive . .
Quick hijack
what digital tyre pressure gauge do you guys recommend
cheers
Grayspoke - a 23 mm road tyre needs 100psi in it to stop the rim hitting the ground. a fat bike tyre 5 psi. Why? because the 5 psi is acting over a much greater area
Grayspoke – a 23 mm road tyre needs 100psi in it to stop the rim hitting the ground. a fat bike tyre 5 psi. Why? because the 5 psi is acting over a much greater area
Yes indeed @tj. Assuming you allow your fatter tyre a larger contact patch, and why wouldn't you? But that is not the ideal gas law or indeed any gas law, it arises from the definition of pressure and a consideration of how a tyre deforms when you squish it (which is easy to visualise intuitively, but would requier some fancy maths to model in a way you can put numbers on). Nobody, certainly not me, is arguing larger tyres don't need lower pressure. But until someone persuades me otherwise, I will continue to say that "gas laws" (by which it appears people mean the ideal gas law) are not the reason why.
Quick hijack
what digital tyre pressure gauge do you guys recommend
cheers
@tranny1 - see this thread
https://singletrackworld.com/forum/topic/what-low-pressure-gauge-for-fat-tyres/
I got an analogue Accu-Gage, which is great (but digital and my eyesight don't get on so well).
Wouldn't inserts help with the squirm, bit heavier mind .
"Ok , so one says put more air in, another says take some out."
Between the two of them they've managed to give you the right advice 🙂 Fanny about with it
If it's a 29er and your fannying about fails, let me know, I'd like to try one of those