I like to lean ... (a story of massive grip)

[2manyoranges]

Well....I do like to mess around with tyres and see what's works and what doesn't. And pressures.

Recently, I terrified myself by trying to run stupidly low pressures to find that you get MASSIVE GRIP......NO GRIP!!! as the tyre collapses sideways in a tight berm. Very Frightening. So I upped the pressure slowly until the sudden collapse stopped - and that was a great sweet spot. For me at 135lbs-ish on the rear that was about 20 and the front about 25. That's with tubeless 2.35 Specialized Butcher (stupid name) and 2.35 Hans Dampf on the front.

Technique wise it is of course all about digging in the side knobs, which means leaning the bike not the body - which gives excessive lean to the bike and really digs those knobs in - and requires deliberate front weighting of the bike. Body upright, lean the bike. Nice. Very grippy.

Then this week I did a few runs to work on my second Roadrat (the rain-focussed one with mudguards) and found something Interesting. The orange Rat has 45C WTB Riddlers on in - nice cheese grater pattern close knob lets down the centre of the tyre and much bigger side knobs. I can lean that pretty dramatically at speed on tarmac but it's always felt a bit squirmy - mainly because the clearances are very tight on the frame, and since I am using 23mm internal rims, the tyre balloon a little at 50-60psi. So the tyres are running a little low re pressure and getting the bike onto the side knobs actually is quite a transition, which results in a very unconfident transition from the centre tread to the side tread. Effect = dodgy handling when leaning.



But the grey Rain-Roadrat has 19mm internal with 35C Schwalbe G-ones - which have a tiny onZa like set of round knobs. But the Good Thing is that the carcass expands at 50-60psi into a really rounded shape - and with consistent types of knobs all over the tyre, there's no weird transition to different sorts of knobs when leaning. This gives immense and consistent grip and so great confidence when really pushing the bike round a tarmac curve. They are really great-performing gravel tyres on the road. On loose gravel they are so so, and cornering or climbing on loose stuff or slop is poor compared with something like a WTB Raddler. But the G-omes are just great for summer and winter commuting on dodgy cycling paths and city streets.

 

[The History Man]

Interesting. I run hard in general being er, larger. Coming from road background this all sounds very scary. Tyres rolling on rims etc.

 

[Retro Spud]

Interesting. I run hard in general being er, larger. Coming from road background this all sounds very scary. Tyres rolling on rims etc.

Good read and challenges my preconceptions which kinda echo THM
A correctly inflated tyre push’s the knobbles /thread pattern outwards which on a curved surface such as tyre is important- under inflate and whilst the tyre will fold around the terrain giving a greater contact area you close up the thread pattern

And then you get into more grip\contact area = greater rolling resistance area …. I ran 1.5 continental tyres on my race bike for years when others had 2.1’s and whilst it generated a hot debate nobody really mentioned tyre pressures just like nobody got to bothered about sag on a fork, travel and rebound speed being king.
One argument being less sag gives you more useable travel and a better ride (a lot of data against that one) and like you detailed above it’s all about finding the sweet spot - which is invariably the most effective compromise between competing forces and starts with the riders weight and riding style

Perhaps if I ran lower pressures and wider tyres I wouldn’t have come off so often
As the old saying goes “before you can win - first you have to finish”

Keep up the testing - and educating the masses

 

[clubby]

Well....I do like to mess around with tyres and see what's works and what doesn't. And pressures.

Recently, I terrified myself by trying to run stupidly low pressures to find that you get MASSIVE GRIP......NO GRIP!!! as the tyre collapses sideways in a tight berm. Very Frightening. So I upped the pressure slowly until the sudden collapse stopped - and that was a great sweet spot. For me at 135lbs-ish on the rear that was about 20 and the front about 25. That's with tubeless 2.35 Specialized Butcher (stupid name) and 2.35 Hans Dampf on the front.

Think I might have spotted your front grip problem in the last six words of that quote.

From your description I don’t necessarily agree you ran out of grip, more that you ran out of support. Obviously the end result is the same, you sh@t your chamois, but it’s not the same. Arguably the tyre was still gripping fine. What carcass type are you using. I’m 90kg and run the same pressure up front. Tougher carcass allow lower pressures while still giving sidewall support. These days though I’m an insert fan, as you can run a lot lower pressures on lighter tyres while the insert gives extra sidewall support to stop the tyre folding in turns like you describe.

For your gravel bike, if you like the G One, I can recommend the G One Bite. It’s like the one in your picture but with a chunkier side tread. Would be a best of both worlds between the two you run.

 

[2manyoranges]

yes that's interesting .... there's a whole 'thing' about whether you can use HDs up front or not....or always use MMs instead. I've used both (and many others), and while HD s are for sure not the ultimate in front traction they aren't actually that bad. But you are right; not optimum. The collapsing through lack of support which I was describing was at the rear, with the weak-carcassed Butcher - a poorly designed tyre I think (weeps buckets of sealant straight through the sidewall all the time)....yes you are bang-on about 'support' being the issue - a rather neglected aspect of tyre performance. I am interested in your experience of inserts, not something we have messed with yet and I need to get some experience and understanding of them.

Actually I have indeed looked at the G-One Bite and will have a go. But the point I was drawing attention to in the post above is that on tarmac it's the transition onto the chunkier side knobs which instils a lack of confidence - and the common knob pattern all over the G-One carcass which allows continuous consistent grip as you go through the lean angles on the tyre which make it a very secure performer....which is interesting.

 

[clubby]

I am interested in your experience of inserts, not something we have messed with yet and I need to get some experience and understanding of them.

Simplistically there are two kinds of inserts. The rim protectors eg Huck Norris, more to do with protecting rim and stopping pinch flats and what I’d call sidewall supporters eg Cushcore or Rimpact.

I’ve only used Rimpact Pro so far and effect is pretty stark. They are a pita to fit until you understand the technique and even worse to remove. They do however perform like they claim. Question is do you need them to? I have them on my bigger bikes and as a chunky monkey, they allow me to use lower pressures for grip but support the 2-3 cm of tyre sidewall nearest the tyre, preventing it from folding in the manner you describe in the original post. With tyre pressure being 4-5 psi lower with them, they also cushion the rim on big rock hits. This support also give a hard to describe damped feel to the ride. Wheels are very quiet with them in. Never punctured with them but if you do they help hold the tyre in place while you slow down and can also be ridden flat in an emergency. Downside is that they are heavier but this is offset by being able to run a lighter more supple tyre carcass. They do also reduce tyre volume and you can feel the tyre bottoming more which can be more tiring on long rocky trails. The damped feel also makes the bike feel less lively on rolling trails.

At your weight, unless you are destroying wheels and pinch flatting all the time, I’m not sure the advantages outweigh the benefits. On my ebike I run them all the time. On my sentinel, I have them in the stock wheels but not my lighter trail wheels.

 

[2manyoranges]

Simplistically there are two kinds of inserts. The rim protectors eg Huck Norris, more to do with protecting rim and stopping pinch flats and what I’d call sidewall supporters eg Cushcore or Rimpact.

I’ve only used Rimpact Pro so far and effect is pretty stark. They are a pita to fit until you understand the technique and even worse to remove. They do however perform like they claim. Question is do you need them to? I have them on my bigger bikes and as a chunky monkey, they allow me to use lower pressures for grip but support the 2-3 cm of tyre sidewall nearest the tyre, preventing it from folding in the manner you describe in the original post. With tyre pressure being 4-5 psi lower with them, they also cushion the rim on big rock hits. This support also give a hard to describe damped feel to the ride. Wheels are very quiet with them in. Never punctured with them but if you do they help hold the tyre in place while you slow down and can also be ridden flat in an emergency. Downside is that they are heavier but this is offset by being able to run a lighter more supple tyre carcass. They do also reduce tyre volume and you can feel the tyre bottoming more which can be more tiring on long rocky trails. The damped feel also makes the bike feel less lively on rolling trails.

At your weight, unless you are destroying wheels and pinch flatting all the time, I’m not sure the advantages outweigh the benefits. On my ebike I run them all the time. On my sentinel, I have them in the stock wheels but not my lighter trail wheels.

That's extremely helpful. I am lightweight and a technical rider, so indeed not a Hoop-Destroyer or suffering from pinch flats. Likewise the whippet-like Grom, who is known as the Drift King in the DH pack in the Alps, but he only destroys tyres, not rims. Very helpful and I will read more....

 

[clubby]

Likewise the whippet-like Grom, who is known as the Drift King in the DH pack in the Alps, but he only destroys tyres, not rims. Very helpful and I will read more....

Definitely sounds like he’d be better with DH casing rather than lighter tyres and inserts.

 

[d00m]

I've always gone for fairly high pressures on the front and make sure I drag a little front brake entering the turn without any rear brake. As long as the tyre is pressed into the dirt it's doing its job