SaxonRider on his new Genesis Tarn 10 with 3.0 tyres is still about 10kg lighter than me, but on typical stony but not really rough trails, he rolls much faster than me. I’d have expected plus tyres to be MORE draggy, not less. Very surprised.

A low pressure tyre will deform much more over small irregularities. That means that forward momentum is not being converted into vertical motion, lifting the weight of bike and rider.

On anything more rough than a well kept fire road, wider + lower pressure = faster rolling given the same quality tyre casing.

If you go dig around on Schwalbe’s website they did a study on it ~5yrs ago.

That was my conclusion also as I was running almost 30psi.

Still surprised though.

Were you on the fully rigid MG ?
Suspension would create the same effect as the larger softer tyres.

Yes, fully rigid. Would have been very interesting to see a FS bike alongside.

Suspension would create the same effect as the larger softer tyres.

Don’t think so, on a suss bike, bumps from stones would shift the wheel and the fork lowers and compress the suspension, taking more energy from your forward motion than the fatbike tyre just deforming in a different way and the trajectory of the wheel, hub, forks not being affected.

SaxonRider on his new Genesis Tarn 10 with 3.0 tyres is still about 10kg lighter than me, but on typical stony but not really rough trails, he rolls much faster than me. I’d have expected plus tyres to be MORE draggy, not less. Very surprised.

Yeah, that sounds about right – my experience is that they’re super fast on the sort of choppy, uneven stuff where normal tyres seem to hook up and lose momentum on every small rock or lump. It’s like the opposite of riding a cross bike on small, rocky chunder. It’s post-truth mountain biking. Not.

I was surprised to find that my 35lb fatbike with its 4.8″ tyres was faster up some climbs than any of my, much lighter, “normal” bikes. I eventually concluded that there must be less rolling resistance, which more than makes up for the extra weight.

Not every climb, I hasten to add. It sucks big time on the road, for example. But on the sort of slightly rough, stony tracks that I spend a lot of time on it it quite a revelation.

I still struggle to see what plus size tyres are about. Genuinely interested in all things bike by the way, I just can’t work out how it would be better for the riding I do – lakes fell riding and/or steep muddy stuff in the trees when the weather is bad.

Anyone care to enlighten me?

Just getting to grips with my Puffin on 4″ rubber.
It feels no slower than my 3″ tyred Niner that’s 5lb lighter.

fifeandy – Member

If you go dig around on Schwalbe’s website they did a study on it ~5yrs ago.

Annoyingly, they didn’t go below 20PSI at the time though. A couple of years back I messed around a lot with pressures between 11 (thanks Procore!) and 20. At first it was just for a laugh because I could, and I was surprised when it sped me up quite a bit on descents.

Ended up settling on 17PSI for my body weight and setup with a 2.4 tyre, just to stop the pogo bounce of lower pressures on climbs, and I’ve found the same happens with plus tyres if they’re too low.

roverpig – Member

Not every climb, I hasten to add. It sucks big time on the road, for example. But on the sort of slightly rough, stony tracks that I spend a lot of time on it it quite a revelation

Found the same with my fatbike. I’ve got a short sharp climb that is quite stony in places that I’ve tried a variety of bikes on. Fastest by far (and easiest) is on the Pug.

Neb – define better. On “fell riding” (presume predominantly grassy) they feel slower and traction isn’t really any better. Muddy forestry off piste, they’re pants. On rockier stuff, they’re a hoot and on loose stony surfaces traction is improved.

I still struggle to see what plus size tyres are about. Genuinely interested in all things bike by the way, I just can’t work out how it would be better for the riding I do – lakes fell riding and/or steep muddy stuff in the trees when the weather is bad.

Maybe it wouldn’t.

Maybe it wouldn’t.[/quote]
That.

Choice is good. It means we can each find something that works for our riding and those who have a different type of riding can do the same.

I do enjoy watching fat bikes overtake me on fire road climbs.

It’s the noise they make and everything! Still never had a go at one, would like to one day though.

So, the key question, this being STW, is which is faster – a single speed 29er or a single speed 650B+?

My Niner was definitely faster on regular 29″ rubber particularly around Cannock.
Running b+ / 29+ it’s just more fun.
To some, fast means fun, & that’s fine.
But the plough through everything attitude of plus sizing is just a laugh. Like being on a big BMX.
If I get on with the Puffin, bought more as an experiment than anything; then the Niner will go back to 80mm travel & regular 29″ wheels & tyres. Both the Niner & Puffin are singlespeed, & the Puffin will probably end up a proper 29+ machine. The 4″ tyres are ok but a few rides in my money is on the 3″ size.

I just can’t work out how it would be better for the riding I do – lakes fell riding

I reckon they would be great on loose rocky stuff.

Thinking I could benefit from wider rims on the 29er with 2.35s on. I currently run 30psi to avoid bounce and squirm.

Definitely interested in B+ wheels for it now though too. But it’s non boost – would this be a problem?

Also – a lot of my rides are mixed road/off. Plus would be a downer on the road bits. Just got hold of some boingy forks, wonder if that will help the climbs…

Isn’t the tyre clearance more the problem than the hub spacing?

Obviously the whole idea is dependent on clearance too. I know my rigid fork can take 29+.

So in terms of wheels I need:

700c x 40c
29 x 2.35
27.5 x 3.0
29 x 3.0 front only

Seven wheels for one bike.

So, the key question, this being STW, is which is faster – a single speed 29er or a single speed 650B+?

Well on Sunday I was out on my 650+ SS with 2 29er SS’s and a fat SS sll rigid. Sadly my chain kept coming off so no winner could be declared.
But for the sake of this thread I was the fastest. By miles.

Hope that helps

Sorry boxelder, by fells I meant just typical lakes riding.

I think I was struggling to see how plus size tyres would help with rocks. How are they better than correctly setup suspension? I also cant see plus size tyres being as tough for the same weight.

But obviously I’m still curious!

The thinner tyre at high pressure = faster ‘fact’ has been reinforced and regurgitated for so many years that it takes a while to accept that bigger tyres at low pressure roll better on rough surfaces.

I think I was struggling to see how plus size tyres would help with rocks.

Plus tyres are pretty big. They can deform over rocks and grip them. A normal wheel at higher pressure is still bounced out of the way. It’s just that the bike itself isn’t bounced as much.

If you are talking big rocks, then plus tyres won’t be any substitute for 6″ of travel, of course.

Taking this to the extreme, I was in a group riding down a gently inclined dry river bed in Morocco a few years back. Think really big gravel, round and loose. I was the only one on a fatbike.
The skinny tyred bikes coped okay, but everyone else was pedalling with a fair bit of effort. I glided serenely down the trail without a pedalstroke. 🙂

But remember, the endoooro guys don’t like plus tyres so they must be rubbish.

But surely tyres soft enough to deform over big gravel = pinchflat at higher speed with bigger rocks. And also equals tyres rubbish at holding an edge while cornering?

I’m also struggling to get my head around why you’d want your tyres to conform around big gravel?

I’m just trying to see what the fuss is about, the industry has been pushing it hard and I’m still not quite sure whether it’s actually going to help my riding on my current bike.

I can certainly see the attraction of a no fuss rigid bike, using bigger tyres to up the comfort in the absence of suspension. But on a 165mm trail bike?