Dammit! I demoed a Yeti SB5.5c today Anyone else see unicorns?

[Mike Thomas]

Okay, fair enough, but my point is that if I came into your shop and you put ME on a bike, I'd hope you wouldn't let me go out on 30psi tires.

Of course. I don't think everyone else needs or wants the same thing as me.

 

[Ron]

are you trying to start a war here?

Here's a general idea from what I could glean from MTBR posts.

2.25- 2.40 tubeless and under 30ID= 22-26 rear, 20-24 front---- 30 and over ID, drop 2-4psi each

2.40-2.6 and 30-35 ID, = 14-16 rear, 13-15 front REVISED: 16-18 rear , 15-17 front.

2.8- 3.0= try reducing 2-4 psi.

all subject to rider preference--- and weight. Thanks @Tom K.

 

[Mike Thomas]

Could one of you knowledgeable people post a rule of thumb for various situations? (Tire size + wheel size + ?? = absolute number, weight / foo, etc)

If anyone actually provides you with a formula like this, they are full o' shyte. There is no 'right/ best'. It's worth seeing how low you can go. Traction is wonderful, but there are limits. Those limits involve riding style and speed... which makes any equation so personal that they become kind of useless.

 

[Mike Thomas]

Ron is giving general guidelines, which is not what I was referencing. I'm not calling you FoS.

 

[Mike Thomas]

Also Ron, to answer your question, my wheels are older i9 Enduro, I believe 24mm id.

 

[Ron]

I think you were clear that there is no "formula" that a rider could use.

 

[Ron]

Also Ron, to answer your question, my wheels are older i9 Enduro, I believe 24mm id.

I think it would be interesting to get feedback from skilled riders who could test their experiences with differing rim ID's and tires.

as an intermediate, I could certainly tell the difference once I was testing on a 30-35 ID,but not at the forces many of you ride at. It was really evident when I went from the Trek Fuel EX with 30's mounted with 2.25's and then rode that Primer with 21 ID wheels with 2.25.

 

[Jwrags]

Getting back to the bike, very nice looking ride, @Ron! I am amazed at the cost of a quality mountain bike, especially compared to road bikes. Maybe I'm wrong, but I feel that a comparably equipped road bike is significantly less than its mountain bike cousin, not that you can't spend a fortune on road bikes.

 

[Ron]

Think about the extra parts and r&d on a fs bike. You are correct though. I compared all of the bikes with near identical build levels and all were within 300-500. Fortunately i had $4k from my last bike. Its pretty much $7k map for a carbon fs with Xo1 eagle. Then add carbon wheels. You can buy the yetis in the regular carbon version and save about $1k. You really don't give up much The fork and shock are performance level. VS factory, you get a X1 crank vs xo1 crank, and you get guide r brakes instead of the much nicer guide RS's. The regular carbon weighs about 250-300 grams more.

 

[AmyPJ]

Quoted for truth. Specifically, for me, this invariably means letting a bit of air out of suspension and a ton out of the tires. Who rides 2.35 29ers @ 30psi ???

The term "ping pong" comes to mind at 30 psi Of course, that's on tubeless.

I'm intrigued about the 13-14 psi being mentioned. I've always run at 16-17, but on my old bike. On the new bike, that feels a bit firmer. Wondering if my climbing issues on loose stuff and a few other things could be helped a little by running around 14-15 psi?

 

[Ron]

First thing would be to adjusting sag a bit. Not sure what you have on the shock and fork but going from 25% to 30% might make a significant difference. What tires and wheels are you running.

 

[Erik Timmerman]

I also run 30 psi. Well, 29psi to be exact. I run 27 rear and 25 front on my DH bike. I will increase both if I'm expecting to be railing tons of berms.

 

[Monique]

I also run 30 psi. Well, 29psi to be exact. I run 27 rear and 25 front on my DH bike. I will increase both if I'm expecting to be railing tons of berms.

indeed! I was going to ask about PSI when doing jumps etc!

 

[AmyPJ]

First thing would be to adjusting sag a bit. Not sure what you have on the shock and fork but going from 25% to 30% might make a significant difference. What tires and wheels are you running.

Already adjusted this, but probably closer to 25%.
Tires are the Bonti XR3 Team Issue 2.4, and wheels are the stock Bonti that came with the bike. I want to say they are 29mm wide. Old tires were 2.3s on the old bike.
I'm kind of jonesing to try a 27.5. Am wondering if that long wheel base isn't hurting me on the 29er.

 

[Monique]

Am wondering if that long wheel base isn't hurting me on the 29er.

Careful, careful! It's much more expensive to cycle through bikes than skis ...

 

[Monique]

@Ron - I did find out one more difference with the Beti - lighter wheels.

Apparently the different shock has something to do with smaller tubes/channels for lighter riders. I didn't quite follow, TBH.

 

[Tony S]

Careful, careful! It's much more expensive to cycle through bikes than skis ...

This!!!

 

[Tony S]

Data point on tire pressure, fwiw. I am 125-140 before gear. (Gained 10 in the last year, so now at the top end of that.) I run 14 - 18 psi front, 16 - 22 psi rear. This is for a 29 x 2.25 - 2.4, tubeless.

 

[Ron]

I also run 30 psi. Well, 29psi to be exact. I run 27 rear and 25 front on my DH bike. I will increase both if I'm expecting to be railing tons of berms.

Interestingly, on my trance with 24.5 id's and 2.35's I ran 22 front, 26 rear for a happy medium of tire rolling, deformation and sidewall support. So we have 3 groups of psi here. I get you and mike running the 30 for sidewall support and I am certainly not telling you what to but what's your take on what maxxis, ibis and enve are saying regarding using a 30-35id with a the DHF/r's (in your case) in the WT build for tires that can be run at much lower psi but offer even more casing support? They roll faster, and offer far better traction while still proving the support you guys need?

 

[Ron]

Already adjusted this, but probably closer to 25%.
Tires are the Bonti XR3 Team Issue 2.4, and wheels are the stock Bonti that came with the bike. I want to say they are 29mm wide. Old tires were 2.3s on the old bike.
I'm kind of jonesing to try a 27.5. Am wondering if that long wheel base isn't hurting me on the 29er.

Oh, unless you want to go the route of a bike quiver, be careful

Each will offer something different so just be aware of that and then setup your bike to what works best for you. I would suggest that you set your sag closer to to 30% of usable stanction travel . Just ride with a shock pump in case that's too soft but my guess you will like it. You may want to adjust the damping a couple of clicks and see how that works for ya' as well. Make sure that rebound isn't too high. It sounds like you are comfortable tweaking your bike so play around with it some.