Enduro/gravity bike suspension and geo

[Bos]

Maybe you need more psi for your, er, bodyweight. I run 35psi and rim dingalings are few and far between. 2.4 dhr on 35mm internal rim, for science.

 I was "running" 33PSI at Jonkers last year and Im (70KG's) for all the rides before the Enduro Nationals, and never had a pinch, only suffered a small ding. 

 

In the beginning it feels a bit hard but one gets use to it. I'd probably prefer that over the 1000g's DD casing and inserts would weight.

 

On EWS Youtube channel https://www.youtube.com/watch?v=lb_puXicyKo Ric McLaughlin asks the riders what they are running.

 

Pinkbike did a whole spread on DH tire pressures.. If I recall the DH guys were running 25PSI front and 32rear? Thats less than what I run, but I suspect its because they run DH casings and all of them use inserts these days. 

[Jewbacca]

 I was "running" 33PSI at Jonkers last year and Im (70KG's) for all the rides before the Enduro Nationals, and never had a pinch, only suffered a small ding. 

 

In the beginning it feels a bit hard but one gets use to it. I'd probably prefer that over the 1000g's DD casing and inserts would weight.

 

On EWS Youtube channel https://www.youtube.com/watch?v=lb_puXicyKo Ric McLaughlin asks the riders what they are running.

 

Pinkbike did a whole spread on DH tire pressures.. If I recall the DH guys were running 25PSI front and 32rear? Thats less than what I run, but I suspect its because they run DH casings and all of them use inserts these days. 

They also go 500 times faster than us, so the tire squirms more and ledges become LEDGES.

 

It's really difficult to look at what a pro is running and make it relate able to hackers like us.

 

The physics change massively with the speed and the sheer size of the things they hit.

 

I run both my tires well under 2 bar / 29psi with no inserts and no DD/DH casings and hardly flat.

 

BUT I'm also bog average.

 

I'm sure my exact lines at 33% faster would yield very different results.

[Captain Fastbastard Mayhem]

I was "running" 33PSI at Jonkers last year and Im (70KG's) for all the rides before the Enduro Nationals, and never had a pinch, only suffered a small ding.

 

In the beginning it feels a bit hard but one gets use to it. I'd probably prefer that over the 1000g's DD casing and inserts would weight.

 

On EWS Youtube channel https://www.youtube.com/watch?v=lb_puXicyKo Ric McLaughlin asks the riders what they are running.

 

Pinkbike did a whole spread on DH tire pressures.. If I recall the DH guys were running 25PSI front and 32rear? Thats less than what I run, but I suspect its because they run DH casings and all of them use inserts these days.

Enduro field was pretty standard between 23&28 if I remember correctly. There was a tech vid about it.

[Headshot]

Interesting chat this is... I am running my narrow HT rims with 2.4 tyres. Pretty wide and decent volume. Even down to 25psi out back they still work fine, no rolling off the rim and never any air loss due to burping. This really does go against the wider is better argument and part of my motivation for looking at a narrower, say 25mm rear rim.

 

You do get used to harder tyres but both my bikes feel better at slightly lower pressures especially out back.

 

Yes, the HT is riddeen with greater care and in general the speeds are slower, although it can even be faster in the right terrain.

 

Im going to carry on playing and see where this leads..

[mazambaan]

I am not really an enduro rider and run my tyres just under 2bar, normal tubeless BUT it is irritating when you hammer through a rocky section only to exit with a sad wheeze as the last of the air puffs out of the tyre. Investigation (re-inflating) shows that the bead or just near it is damaged and tyre is junk.  2 or 3 like this; Grrrr.

 

Last one was a week ago, quite new (fitted in August 2019) Continental XKing 2.4 junked over a few rocks. Now trying on new but been "in stock" for some time Rock Razor; 1kg of rubber beef, I hope.

[usxorf]

Yep I'm on a rim a year, and actually accept it. There's foam inserts there's dh skin tyres there's rattle my spine pressures and then there's trail stoke and bad luck. The last is me

 

 

 

 

 

 

 

 

.... At least that's what o tell myself

Aren't you already on one taco for the year, and it's only Januworry...?

[PhilipV]

Tyres and rims cost about the same these days. My new bike will just have RAPIDE TR30 rims, which are for argument sake, trail wheels, but there was very little difference to the Spanks I upgraded to.

 

If I have to replace a R900 back rim once every 1.5 years. I can probably live with it.

I've just rebuilt my back wheel with a Rapide rim. Took the time to learn how to do it myself, so I agree with you.

[Meezo]

Aren't you already on one taco for the year, and it's only Januworry...?

Correct!

[Bos]

They also go 500 times faster than us, so the tire squirms more and ledges become LEDGES.

 

It's really difficult to look at what a pro is running and make it relate able to hackers like us.

 

The physics change massively with the speed and the sheer size of the things they hit.

 

I run both my tires well under 2 bar / 29psi with no inserts and no DD/DH casings and hardly flat.

 

BUT I'm also bog average.

 

I'm sure my exact lines at 33% faster would yield very different results.

 

That was kind of my point.. If I'm running my rear tyre 33PSI but the DH kings are running less than me, the Casings and inserts makes a bigger difference then what I'm giving it credit for?

 

Perhaps worthwhile getting the DD casing on the rear (AGGRESSOR) since it doesn't seem to exist in EXO+ yet?

 

No Question about it though, 28 PSI feels much nicer then 32PSI.. I'd probably run 28 if I had DH casings, but I am trying to keep my bike as light as possible. 

[Eddy Gordo]

sorry to say, there is a trade off between lower pressure vs higher pressures. One is not better than the other. You have to sacrifice rigidity in lower pressure with greater chance of dings. Or some grip with higher pressure and extremely less chance of dings.

 

In the 4x4 world, we use very low pressure 0.8bar for deep sand driving. Gravel roads is 10% off your normal pressure.

 

I run high pressure, now again I just so happen to have a sweet spot and sometimes soft enough where the rim dings. Finding the right balance between hard and soft id what ill work. Non of my rear wheels are below 2 bar. The front is currently at 0.9 bar. I have the wtb tough casing and a foamo in the rear. It has save me numerous times and even allowed me to pedal back slowly without tyre damage.

[Eddy Gordo]

XC 

• 20-25mm internal width range
• Generally suited for 2-2.25″ wide tires

Trail

• 23-27mm internal width range
• Generally suited for 2.25-2.5″ tires

Enduro/dh/ freeride

• 27-35mm internal width range
• Generally suited for 2.3-2.6″ tires

Plus size

• 32-50mm internal width range
• Generally suited for 2.8-3.8″ tires

https://www.singletracks.com/mtb-gear/can-i-run-a-wide-tire-on-my-rim-mountain-bike-rim-widths-de-mystified/

[Eddy Gordo]

"The other area worth noting is the consistency of times between the 30mm and 35mm rim - much of the conventional wisdom suggests that a 2.35 tire on a 35mm rim is a less than ideal combination, but in terms of times and feel, it is hard to separate the two - it follows that wisdom in losing some side bite, but the profile of the carcass is better."

 

'If your question is: "My current rims are narrower, should I upgrade them?" In honesty, I would have to say no. If you are used to riding your current rims, why worry? Unless you have the chance to ride wider rims, you'll never know their benefits. In terms of outright performance, good geometry, suspension, and brakes are always more important"

 

"The other area worth noting is the consistency of times between the 30mm and 35mm rim - much of the conventional wisdom suggests that a 2.35 tire on a 35mm rim is a less than ideal combination"

 

https://www.pinkbike.com/news/rim-widths-comparison-test-mountain-bike.html

[Hairy]

I use the tried and tested squeeze test, first founded on old 26'ers with beefy 26x1.95" tyres back in the day.

[Headshot]

Started running my back tyre at 32psi. Rides horribly on the flat rocky stuff at Tokai but is great on the downhills. Also requires a slower rebound to compensate for the extra bounce.

[stefmeister]

Started running my back tyre at 32psi. Rides horribly on the flat rocky stuff at Tokai but is great on the downhills. Also requires a slower rebound to compensate for the extra bounce.

 

Interesting that you mention that. I never consider rebound and tyre pressure, but I do prefer the way the bike's suspension feel when I run higher pressure. Just clicked now. Running 23/30. Have run 20/23 in the past and no issues, but then again I way ~72-75.

[RiverInTheRoad]

I have found that nothing has a bigger effect on riding comfort than tyre pressure. I try to go as soft as is practical. 

 

My current setup:

 

29mm internal rims (FLOW MK3)

 

Front: DHF 29x2.5WT EXO - 1.4bar (20.3 psi)

Rear: DHR 29x2.4WT EXO - 1.5 - 1.6bar (22-23 psi)

 

With these pressures my tires get those diagonal lines which are typically from tyre squirm. They only burp (I don't really feel it that much on other trails) on extreme high g-force berms like at G-Spot. My mass is around 86kg with riding kit.

 

As mentioned tyre pressure also has a knock-on effect on your required suspension rebound setting! 

 

I have a Specialized Stumpjumper 2019 and basically followed the Bike Setup Tool on their website. Which I found was an extremely good base setting. I am on the lower end of their suggested tyre pressures.

 

PS: I measure tyre pressure with a Topeak digital gauge (floor pumps can be way out!)

Edited January 29, 2020 by RiverInTheRoad