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"the" fashion advisor
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Discussion Starter · #1 ·
Alright, so I'm 3 months into the 29er conversion and very happy with the move to big wheels. My only compalint---it seems like nearly every ride I end up with a flat tire these days. I ride the midwest (Kansas City) and while some of our trails are flowy and buffed, we also have our fair share of rock gardens and technical obstacles and of course this seems to be the stuff that gets me. So far, all of my flats have been pinch flats, at least as far as I can tell.

My wheel/tire setup---King ISO disc hubs laced to Salsa DelGados and running Mythos tires (front and rear specific treads) with WTB 29er tubes. I've been starting out my rides lately with around 35-37 PSI in the tires and weigh around 160-165. I am a "light" rider and am one of those guys who has never had a wheel come out of true in many years of riding and I rarely (like never) break things--I know, I'm jinxed now. (Bike is a MootoX for what its worth).

I realize the simple answer is more pressure, but I don't like the loss of traction and increased roughness that comes with that so I'm curious, what sort of PSI are others running? Granted, your terrain, weight, riding style etc may vary but just curious. Am I way off the scale in terms of where I should be pressure wise? Seems like I could do a Stan's conversion as well but I have to admit, I am not super crazy about running non-tubeless tires in a tubeless setup. I know folks do it, but it sure seems like a recipe for disaster.

So, talk amongst yourselves...thoughts? Thanks!!!
 

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Just Ride!
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I can't speak to a tube solution at the pressure you want to run, because I don't think there really is one for our area. I can say though that I have been riding tubeless at 25-30psi in KC area for over a year and have not had a flat to date.
 

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Always Learning
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Chic said:
...so I'm curious, what sort of PSI are others running? Granted, your terrain, weight, riding style etc may vary but just curious. Am I way off the scale in terms of where I should be pressure wise?!
I weigh between 190 - 195. Bontrager ACX using WTB tubes at PSI of 32-34 psi on my Sugar. Bontrager ACX using Bontrager slime filled tubes at 30 psi on my Karate Monkey. No flats in a year on either. Riding terrain includes anything from thorn filled trails, gravel, grass, rocky terrain in the Black Hills, logs, roots and creek crossings.

I did have flat troubles on the Speedcity's until I switched to the slime filled tubes. No flats since switching and I've lowered my psi because of it.

BB
 

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I get tons of pinch flats as well. The problem I had with tubeless is that I still got pinchflats (somewhat less often) when the rim cut the tire casing. If it was a small cut the goop sealed it but I had to stop and pump. Larger cuts and bead farts were a fricking mess with goop everywhere while I removed the sealed rimstrip/stem and put a regular rimstrip and tube in. You can't reseat the tire with a minipump. That, combined with the additional expense and time setting it up made me go back to tubes.

I've been 6 rides in Moab and rocky VA without a pinchflat using a Motoraptor rear and a QBP 29er tube. 170lb / 30 psi. As far as I can tell a mid size tire (2-2.1) with large densely packed knobs gives the best pinch resistance. Huge tires are ok, but only with huge tubes. I didn't have much luck with the Klaw or ACX in back, but I only used them for a few rides before switching back...luck has a lot to do with it too.
 

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"the" fashion advisor
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Discussion Starter · #5 ·
BruceBrown said:
I weigh between 190 - 195. Bontrager ACX using WTB tubes at PSI of 32-34 psi on my Sugar. Bontrager ACX using Bontrager slime filled tubes at 30 psi on my Karate Monkey. No flats in a year on either. Riding terrain includes anything from thorn filled trails, gravel, grass, rocky terrain in the Black Hills, logs, roots and creek crossings.
BB
700c slimed tubes or the 26" variety with a bit of a stretch? thanks for the info folks!
 

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Always Learning
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My gloves stink
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An oft asked question, that.

I also experienced frequent pinch flats trying to run pressures in the sub 30 psi range. Why did I run such low pressures? Because there are lots of guys on this forum who swear that they run 25 psi without problems! And yes, they're using tubes. I've found that I have to run 35 in front and 37 in back to avoid the pinches. I weigh about 170 lbs, ride conservatively, but do tend to careen uncontrollably into some sharp-edged rocks now and then.
 

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Only dead people are old
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Appendage said:
I also experienced frequent pinch flats trying to run pressures in the sub 30 psi range. Why did I run such low pressures? Because there are lots of guys on this forum who swear that they run 25 psi without problems! And yes, they're using tubes. I've found that I have to run 35 in front and 37 in back to avoid the pinches. I weigh about 170 lbs, ride conservatively, but do tend to careen uncontrollably into some sharp-edged rocks now and then.
I got my first pinch flats just this year due to several factors I think. My downhill speeds are way up now and I'm usually running as low a pressure as possible. So far all my pinch flats have been on the rear of my hardtails (both SS and geared) and I have had none on my FS. I'm a light weight at 147lbs and ran 28-32 psi during fast (yet very controlled) downhills on trails with rocks when I pinch flatted. After my third pinch flat in 2 weeks I started running 34-36 on rocky trails and have not had anymore. With my Stans wheelsets (with IRC tires) I have never had a problem running 28-32psi, but Stans is not for every tire so tubes are a must for some.
 

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Squalor
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6'1
160-165 lbs ride weight

KM Rigid SS
- 25 PSI in rear ACX or Nano
- 22-25 PSI in front ACX or EXI

IF Geared w/ REBA
-25-28 PSI in rear Moto
-25-28 PSI in front ACX or EXI

I always use WTB or Bonty regular (not the light) 29er tubes

I rode the Moto / ACX combo on the IF this weekend in AR at about 28 PSI front and rear, and did not have any problems at all.

LP
 

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6' , 200 lbs and in 5 seasons of riding 29"ers I have had exactly 0 pinch flats using 30 lbs or less psi with tubes (mostly WTB and some Bonti) and mostly Nanos on the rear end but other tires used also. FS, Front S and Rigid bikes ridden over mostly rocky terrain.

Willits was a big believer in the 30 and under psi and almost everyone here in the Butte rides those pressures and I have never heard of or seen of alot of pinch flatting. I used to pinch flat some on 26" with 45 lbs pressure however. Perhaps you need to lower your pressure instead of raise it? I know it sounds wrong, but what is right?
 

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Only dead people are old
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Bigwheel said:
...Perhaps you need to lower your pressure instead of raise it? I know it sounds wrong, but what is right?
When you feel your rim hitting rocks there is a problem with your tire pressure. I notice some tires give much more than others in the sidewall so maybe it's more tire dependent.
Also like someone above said - light weight tubes are much more prone to pinch flats.
 

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Super E said:
I notice some tires give much more than others in the sidewall so maybe it's more tire dependent.
I agree there. I've had problems with pinches and thorns in my Kenda Klaw on the rear, I'm switching to an IRC in the hopes of preventing flats. I've never had a problem with thorns in this area with ANY 26" tire I've run. I hate flatting during races.....
 

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No pinch flats until I switched from road rims.

(I normally just lurk here but when something strikes a chord....) ;^)

I built up my KM in '03 and I "made do" with my road bike wheels (with Mavic CXP33 rims) for a while, using the Kenda Klaw tires. (BTW, they work great for me in WV.)
When I got my dedicated 29" wheels (using the Delgado rims) I suddenly started getting pinch-flats on the same trails I'd previously had none on. I've had to go up to ~38 psi to avoid the flats ( We ride a lot of streambeds.)
FWIW, I'm ~170 lbs and have always been easy on my wheels, with nary a pinch-flat.

My conclusion is that, as the rim gets wider, the spreading out of the tire means that there's simply less tire/tube/air between the rim and the ground to avoid pinching the tube.
I was fortunate to meet Wes Willits last Summer and he was of the same opinion. As evidence, he showed me several of his wheelsets built with Open Pros.
My intent is to build up a new set of 29" wheels using 36-hole road rims.

steve
 

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Recovering couch patato
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One far-fetched variable with pinchflats : arm length. Mine are huge, and I think on top of that I unconsciously use them to smoothen the ride (lots of elbow movement). The more the elbows suck up from a blow, the less will have to come from the tire. Tire travel = 2", my arms ~ 10". With ridig arms I'm sure I'd bottom out all the time.
I weigh 190lb and although my trails are pretty lame, I hardly imflate higher when I go on a rare ride on proper trails. My favortire pressure with nano's is around 30lb, a bit less with XR's. The front XR at 3psi just seems so harsh and bouncy, the volume asks for lower psi.
 
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