27.5 plus tyre thread

[mitchy_]

has anyone played around with plus tyres enough to know how they stack up width wise?

currently i'm playing with a pair of Specialized Purgatory's on 30mm ID rims. they are measuring in at 75.5mm across the tread, and 69.2mm across the casing.

up front in a 29" non-boost fork this is fine, just.
it also fits in the rear of my frame, however there is a metric bee's dick clearance to the chain stay so a downsize is required. we've got an Ikon+ 27.5x2.8" on the way, but i'm also interested in what widths some of the other plus tyres like the 2.8 and 3.0 nobby nic are to see what i can squeeze.

 

[Ivan]

Mitchy, Did you see the recent Dirtmag test using the Enduro and plus tyres? https://dirtmountainbike.com/bike-r...ed-enduro-29-six-ways-three-wheels-sizes.html

MTBR has a forum with the most information around i think http://forums.mtbr.com/26-27-5-29-plus-bikes/

 

[mitchy_]

Mitchy, Did you see the recent Dirtmag test using the Enduro and plus tyres? https://dirtmountainbike.com/bike-r...ed-enduro-29-six-ways-three-wheels-sizes.html

MTBR has a forum with the most information around i think http://forums.mtbr.com/26-27-5-29-plus-bikes/

yep, i have read that the dirtmag test. they only use 2.8's front and rear though. ideally i want 3" up front, and either a decent sized 2.8" or a 'small' 3.0" in the rear.

i'm slightly dubious of the figures in that test, as they claim going to 27.5 front and rear changed the head angle. surely the only change would be a lowered bottom bracket?

MTBR seems to have a bit of info if i dig deep enough, cheers.

 

[The Duckmeister]

i'm slightly dubious of the figures in that test, as they claim going to 27.5 front and rear changed the head angle. surely the only change would be a lowered bottom bracket?

Your dubiousness is warranted; if the change in wheel/tyre size is the same at both ends there is no change to the bike's angles, it just gets lower.

 

[Ivan]

I think they are comparing it to the 29er with the ohlins shock but without the 650 link

THE SIX WAYS FEATURING TWO SHOCK LINKAGES, AN OFFSET AND SOME WHEEL/TYRE COMBOS

29” LINK GEOMETRY:-


SET UP ONE – 29” WHEELS/STANDARDGEOMETRY


Bottom bracket: 351mm Head angle: 67.5


SET UP TWO – 29” WHEELS/STANDARD LINK, MONARCH DAMPER AND OFFSET


Bottom bracket: 348mm Head angle: 66.5





650B SHOCK LINK GEOMETRY:-


SET UP THREE – 29“ WHEEL FRONT AND REAR – OHLINS DAMPER


Bottom bracket: 338mm Head angle: 67


SET UP FOUR – 650B REAR 29” FRONT – OHLINS DAMPER


Bottom bracket: 332mm Head angle: 65


SET UP FIVE – 650×2.4 Rear 650×2.8 front 650 Link Ohlins damper


Bottom Bracket: 325mm Head angle: 65.5


SET UP SIX – 650+ Front 650+ Rear 650 Link Ohlins damper


Bottom bracket: 329mm Head angle: 66




Read more at https://dirtmountainbike.com/bike-r...s-three-wheels-sizes.html#j5JD8SOceyR1ZvhA.99

 

[mitchy_]

I think they are comparing it to the 29er with the ohlins shock but without the 650 link

still has me baffled.
the eye to eye (or eye to strut in this case) on the ohlins shock is still 216mm, the only difference is the stroke is 63mm (as used on the enduro evo to get 180mm travel) instead of the 57mm on a normal enduro.

that also has 'setup 3' under the 650b shock link geometry list.

650B SHOCK LINK GEOMETRY:-


SET UP THREE – 29“ WHEEL FRONT AND REAR – OHLINS DAMPER

either way, the wife has just given me approval to buy some 27.5" wheels... so i'm jumping on that and will sort out tyres later. :lol:

 

[Ivan]

Yeah Dirt are not the clearest when it comes to details in their articles. I am still not sure what the go is.

What wheels you getting? The AC Smokin Guns look good, but could be a bit wide for the enduro rear end (40mm internal i think).

 

[mitchy_]

Yeah Dirt are not the clearest when it comes to details in their articles.

What wheels you getting? The AC Smokin Guns look good, but could be a bit wide for the enduro rear end (40mm internal i think).

i need to do some research first as i don't know where i need to compromise between rim width and frame clearance, but i was looking at the Light Bicycle 40mm asymmetric rims.

this guy is running Nobby Nic 3.0 and 2.8 on WTB i45 scrapers, which are 45mm internal. claims no rubbing, but the Fox 36 does have a little more clearance than a pike. i dont think i could handle the weight penalty of a wide alloy rim though, scrapers are north of 600g each.

 

[Ivan]

That looks so cool....:Banane09:

 

[mitchy_]

Almost like it was built for it... It pretty much negates one of the only issues with the Enduro too, a high bottom bracket.

 

[Nambra]

Perhaps have a look at the XM551 rim mitchy? 40mm inner width and 595g.

 

[Warp]

Sorry, I feel very lazy.

How much does a plus size tyre/wheel combo weighs compared to a normal 27.5 set up weighs? Let's assume similar builds for both.

 

[mitchy_]

Sorry, I feel very lazy.

How much does a plus size tyre/wheel combo weighs compared to a normal 27.5 set up weighs? Let's assume similar builds for both.

The current range of plus tyres are pretty bloody light...

A Purgatory 27.5x3.0" on a roval fattie alloy 30mm rim was 50g heavier than my 29x2.5" minion on 30mm carbon rims...

Might have 100g over a similar 27.5 setup?

 

[Warp]

The current range of plus tyres are pretty bloody light...

A Purgatory 27.5x3.0" on a roval fattie alloy 30mm rim was 50g heavier than my 29x2.5" minion on 30mm carbon rims...

Might have 100g over a similar 27.5 setup?

Interesting.

Another silly question in my head is the benefit for lighter riders. Sometimes grip depends not only on contact area, but also how much you can make the tyre penetrate the soil. For a given weight, the wider the tyre, the less the tyre will dig in. Most probably is a non-issue.

 

[HamboCairns]

Interesting.

Another silly question in my head is the benefit for lighter riders. Sometimes grip depends not only on contact area, but also how much you can make the tyre penetrate the soil. For a given weight, the wider the tyre, the less the tyre will dig in. Most probably is a non-issue.

Spikes vs snowshoes. The latter will win on hardback and loose surfaces I suspect. Mud is another matter.

 

[mitchy_]

What he said.

I'm likely going to have a 29 and 27.5+ setup depending on the conditions.

There seems to be a trend forming of people running 27.5x2.8" up front on a standard 27.5 bikes though. Clears both pike and 34/36's and offers more front end grip.

 

[Daniel Hale]

my problem always seems to be a slippery rear end, maybe I'm doing something wrong

 

[mitchy_]

my problem always seems to be a slippery rear end, maybe I'm doing something wrong

are we still talking about bikes here?

what rear tyre do you run? even with the 3" up front, the 2.3" DHRII i had on the rear still did a decent job of keeping up.

Perhaps have a look at the XM551 rim mitchy? 40mm inner width and 595g.

this causes a conundrum... ideally i want ~40mm internal width, but i also want carbon.
most of the more common brands such as Light Bicycle, Zelvy, Derby, etc. make 35mm internal or jump up to 45mm internal... more searching required.

 

[stirk]

are we still talking about bikes here?

what rear tyre do you run? even with the 3" up front, the 2.3" DHRII i had on the rear still did a decent job of keeping up.



this causes a conundrum... ideally i want ~40mm internal width, but i also want carbon.
most of the more common brands such as Light Bicycle, Zelvy, Derby, etc. make 35mm internal or jump up to 45mm internal... more searching required.

Jebus just buy a fat bike already, you know that is where you're heading.

 

[Warp]

Jebus just buy a fat bike already, you know that is where you're heading.

Well, actually it's something in the back of me head. If wider/bigger is better why stop at 2.8"-3.0". Just go full fat 29'er and be done with it.