[redFoxx]

Hey all,
I got three pinch flats this week and I'm mighty mad! It happens at the jump park.

Here's the details, maybe someone has some ideas on why this is happening besides low air pressure:

I ride a Transition hardtail dirt jump bike.
I'm new to dropping the bigger stuff and don't always totally clear them properly. I've been doing drops mostly.
I have a Kenda Kenetic 2.35 folding in the rear and a Kenda Blue Groove Stick-E 2.4 wire bead in the front.
I like to run my air pressure at 25 lbs.
I am 135 lbs.
I'm doing drops of about 3 to 3-l/2' height with a greater width to make the tranny, not always successful there.

This just started happening. One thing is I just got new wheels. I was using 24 spoke XC wheels and upgraded to 32 spoke ones. The front tire is, I think, a 2 ply and the rear a 1 ply I believe. I ran low air pressure. I never got pinch flats then but now I do all the time!

Is this the problem the 1 ply versus 2 ply? Should I be upgrading the back tire? Is it just the air pressure? How low can I run air on the 1 ply versus the 2 ply?

Any ideas?

 

[amydalayna]

no need to run low air pressure in those circumstances. and if you aren't worried about weight... you could always try some DH tubes.

also, how wide are your rims? you might want to give wider rims a try.

 

[Chunky Munkey]

Okay, here is where I found out the real problem with that. When I first bought my bike it came with Maxxis tires on it. Helter on th e front and Skelter on the rear. I didn't know ANYTHING about biking at the time. It was a peice of junk Pacific from Toys R Us. REASON before you all go, "WHAT A FOOL" I didn't want to invest a grand or more into a bike if I didn't like the sport.

So a buddy of mine, on his GRAND bike, got two pinch flats in like two seasons. I never got one. He said it was because I had down hill tires with a thicker wall. So later I bought a nice bike. I bought the same Maxxis Helter and Skelter and walked into my bike shop day one and said, "Put these on." Still to this day, and hopefully opening my mouth up now won't happen tomorrow when I ride, but I have YET to have a pinch flat on my bike SINCE I started riding 11 years ago.

So buy some decent thicker walled DH tires like Maxxis Mobster or Minion, High Roller etc but get the thicker .60 I think it's called and you won't have that problem again.

Considering I have been hitting rocks left and right at high speed, jumping, and normally keep my air pressure so low my tires sag a bit cuz it softens my ride ever so lightly and I like the up hill grab in mud and loose dirt I keep them low, like a radial tire and I have yet to have a pinch flat to this day.

Buy some Maxxis DH tires.

THAT will fix you problem. And I am using the standard, el cheapo inner tubes. $5 at my shop. Buy DH's.

 

[Chunky Munkey]

Hey something else, you buy your rims used or something. A lose spoke or no rim tape might be the problem too?

 

[Snacks]

Buy some Maxxis DH tires.

Word. I have been running Maxxis DH tires for the past 2 years of my 'true' DH career and have never ever pinch flated. I have used the at Whistler, races all over the PNW, Cap Forest, at the Flow Park and never had any issues.

 

[redFoxx]

Thanks for the suggestions. These are new wheels and we checked them to make sure there wasn't anything rough on them and there isn't. So I think I'll rule them out as the source of the problem.

I like running lower air pressure, I just like the feel and control better so I don't want to go higher although I may have let them go a tad too low.

I'm not sure what's the difference between the ply and a thicker walled tire but it seems like that's where I want to go. I have a thick DH tube I can put in it so I may try that first and see how it goes tomorrow. Then if I still have a problem I could get a thicker walled tire.

 

[SuperKat]

Thicker tires are the way to go. The extra weight is worth not having to get pi$$ed off with flats. I run Maxxis Highrollers front and back with Maxxis tubes. About 32 psi but that's my preference for DH.

 

[altagirl]

So buy some decent thicker walled DH tires like Maxxis Mobster or Minion, High Roller etc but get the thicker .60 I think it's called and you won't have that problem again.

It's still the dual ply that you want. For example the High Roller comes in a 60 TPI (threads per inch) in both a dual ply and a single ply. The single ply is the flimsy version that I'd only want to use for XC type riding. To be more confusing, you also have a 60a durometer (vs. say a 40a durometer which is softer) which measures the durability vs. tackiness of the rubber. Which isn't going to affect pinch flats, but I bet if you went into a shop and said you want the High Roller in a 60, I'm guessing you'd get a 60a version, since they're always 60TPI.

Not sure if that helps clarify or confuse...

 

[redFoxx]

Thank you Altagirl for that clarification! We were wondering if the ply was the same as the thickness. I ended up getting a stopgap measure of a DH tube as they were out of the heavier tire I wanted - these just aren't carried by every shop. I also have a hardtail and need a tire that doesn't measure more than the Kenda 2.35 I have on now, so most of the Maxxis are too wide.

Well just for the record Saturday capped me off with 4 pinch flats for the week! Tonight we're going again, same tire and thick tube, 28 psi. I'm doing all my big drops, see what happens. Better be a brand new week for me. :redhot:

 

[altagirl]

Thank you Altagirl for that clarification! We were wondering if the ply was the same as the thickness. I ended up getting a stopgap measure of a DH tube as they were out of the heavier tire I wanted - these just aren't carried by every shop. I also have a hardtail and need a tire that doesn't measure more than the Kenda 2.35 I have on now, so most of the Maxxis are too wide.

Well just for the record Saturday capped me off with 4 pinch flats for the week! Tonight we're going again, same tire and thick tube, 28 psi. I'm doing all my big drops, see what happens. Better be a brand new week for me. :redhot:

Yeah - 2-ply basically just means they're putting two normal sidewalls together as one, for extra strength.

See: http://www.maxxis.com/products/bicycle/faq.asp

Maxxis and Kenda are my two favorite tire brands too. I've ridden a lot of High Rollers (both single and dual-ply for XC/trail riding) and Mobsters, and then we tried Kenda Nevagals out at the Durango National a few years back and loved those, so those have become a staple for the DH bikes.

 

[habitatxskate]

no need to run low air pressure, i used to do that and always went through rims and dozens of tubes..

get mr. tuffy rim liners and some rim tape maybe?

 

[redFoxx]

I like running as low a pressure as I can get away with and I know there's the tires out there to let me do so. I just noticed the difference between the DH and the XC tires. XC tires say to start at 40-60, DH that I saw listed 30-50.

 

[Snacks]

I like running as low a pressure as I can get away with.

Why?

 

[habitatxskate]

Why?

i'm with him, there is no reason too

 

[redFoxx]

Why?

I like the feel and the control. Better traction. I don't feel like my tires are washing out or squirreling around. The landing feels nice. hee hee, maybe a bit of suspension because I have a hardtail.

Talking to Simon of Fluidride, he mentioned that they reduce their air pressure until they start getting pinch flats and then ratchet up a hair and that's where they ride at. But even before talking to him I noticed the difference in my riding with lower pressure.

This could lead to a whole new thread...

 

[redFoxx]

i'm with him, there is no reason too

Her..........

It feels GOOD.

 

[Snacks]

I like the feel and the control. Better traction. I don't feel like my tires are washing out or squirreling around. The landing feels nice. hee hee, maybe a bit of suspension because I have a hardtail.

Interesting. Your tires wash out at the Flow Park? I'm not critizing or anything , it's just that I have never ran any psi lower that 30 and don't really washing out.

 

[habitatxskate]

sorry sorry, her*
if you like the traction, just simply get wider tires.

 

[redFoxx]

Interesting. Your tires wash out at the Flow Park? I'm not critizing or anything , it's just that I have never ran any psi lower that 30 and don't really washing out.

It's just the whole combination of nicer feel and control. I feel some washing out on the bermed turns and more squirrelyness on landing but then I haven't gone higher psi since last year and I've been riding at the Flow Park alot more on lower psi than higher this year.

Right now, I've got the psi at ~28 and going to try it tonight and see how it feels.

 

[redFoxx]

sorry sorry, her*
if you like the traction, just simply get wider tires.

But why advocate higher pressure if lower is possible with the right tire? I have a new wider 2.5 tire in the front but Kenda 2.35 in back. I can't go any wider in back.

 

[altagirl]

Interesting. Your tires wash out at the Flow Park? I'm not critizing or anything , it's just that I have never ran any psi lower that 30 and don't really washing out.

This is where we need to define things. 30 IS low to a lot of people. I know XC folks who use 45+ psi all the time. And if you have a flimsy tire, you can easily get pinch flats at 30psi.

I generally run 25-35 w/High Rollers on my trail bike - varies trail by trail.

 

[altagirl]

sorry sorry, her*
if you like the traction, just simply get wider tires.

That's adding weight for no reason if you can lower the pressure and get an acceptable result. Not to mention frame limitations.

Plus, wider is not always better - sometimes wider tires start just deflecting off rocks, or don't bite as well in loose powdery dirt. I used 2.7s on my DH bike for a while and discovered that in general, 2.5s work better. But both would suck with too much pressure. And especially on a flimsy tire, too low is even worse - they start folding over. So the "right" tire pressure depends on the tire, the conditions, and the rider.

 

[redFoxx]

This is where we need to define things. 30 IS low to a lot of people. I know XC folks who use 45+ psi all the time. And if you have a flimsy tire, you can easily get pinch flats at 30psi.

I generally run 25-35 w/High Rollers on my trail bike - varies trail by trail.

whoa, 45psi? That's just crazy talk.

Just for the record, yesterday I didn't get a pinch flat but I did break my valve stem on my front putting air in, then proceeded to break 3 tire levers trying to get the d%$@ tire off. After that, I was fine..........

I am cursed by the Tire Gods! :hot:

 

[weimie]

Honestly, the only time I get pinch flats is if I'm running too low tire pressure. Happen last weekend at Keystone off a small jump.

 

[S.K.C.]

Here's what you need:

1.) 2-Ply DH casing tires with a butyl csaing
2.) DH tubes with a wall thickness of 1.1mm or more. Maxxis DH tubes have a wall thickness of 2.25mm. The thickest ones you can get are Intense FRO tubes - VERY burly.

3.) MOST important:

Use Talcum Powder

...apply talc to the inside of your tire before mounting it. Dump a liberal amount into the tire and the rotate it a little bit at a time while tapping it gently to coat the inside. Then apply some to the tube.

By doing this, you will allow the tube to move around independently of the inner tire casing during an impact. This does not mean the tube will slip all over the place - it just means that when the tube gets pinched it will be able to slide out of that space getting pinched.

If you are still pinch-flatting after following these suggestions, then you need to increase the PSI in your tires. I know low PSI feels good and gives excellent traction, but do you want to be going through tubes like crazy?

 

[altagirl]

Or just go tubeless and quit worrying about it. (You don't need tubeless tires or rims, just one of those Maxxis rimstrips for it or a 20" tube and some stans.)