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2017 Transition Smuggler XL
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955 Posts
Discussion Starter · #1 ·
29er wheels, WTB KOM i23 rim with WTB rim tape, Onza Canis 2.25 TLR tires and Stan's sealant, 36 psi (2.5 bar) pressure. No problems with initial tubeless setup. I weigh 230lbs with gear.

Problem is that I keep burping the tires. First it was rear tire - I went quite fast over roots and bike slipped sideways. Then the front tire burped twice on really small but technical descents. I was going really slow. I made mistake and put my weight on the front wheel and there was also some sideways movement and tire burped.

After first incidents I increased the pressure but this did not help. I would like to find some other solution and decrease the pressure. Right now the bike bounces too much.

I hope that I can solve the problem without changing the rims.

I thought about adding extra layer of yellow tape to make the tire sit tighter on the rim. Do you think that might help? Or perhaps Onza has just bad bead and something like Rocket Ron would solve my problems?

BTW, on my old bike I used Rocket Rons and Racing Ralphs (UST and TLR) on the Alexrims XCR 100d rim with Stan's yellow tape. I run much lower pressure (2 bar) and had only one burp in three years.
 

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mtbpete
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1,304 Posts
I don't know anything about the Onza tire. It looks like it does not fit very tight. If it mounted easily than it may be a little oversize. Also, are you sure you seated the tire fully? Look all around the tire on both sides to see if the line on the tire bead sticks above the rim all the way around. You can also spin the wheel to see if the tread remains centered or moves back and forth indicated some of the bead is not fully seated.
 

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Ride Everything
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I've run those same tires on ENVE, I9, Mavic, and Rolf rims. No problems burping (knock wood), but the fit was a little on the loose side. I'd try adding one more layer of yellow tape.
 

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Super Moderator
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6,776 Posts
Add more tape and bump up pressure to 39psi. At 230lbs loaded - you are actually at the design limit for tubeless tires, using sealant.
 

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Add more tape and bump up pressure to 39psi. At 230lbs loaded - you are actually at the design limit for tubeless tires, using sealant.
Please share the specific evidence to support this statement

Plenty of people (including myself) run tubeless at or above 230# loaded with much lower pressure. I've been running tubeless for years with only one burp on a true tubeless setup (UST or Tubeless Ready). I've had more burps on ghetto systems but that is more inherent in the setup.

Currently running Blunt 35 rims with Geax TNT tires at 20psi with no burping. Have run Specialized 2Bliss tires on Chargers and Flows at 26psi with no burping. Going way back ran full UST wheels and tires and had one burp over several years when I lowered my pressure below 25 psi on a 19mm internal wide rim.
 

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2017 Transition Smuggler XL
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955 Posts
Discussion Starter · #6 ·
I found the reason. The manometer of my pump was way off. The real pressure in tires was around 1.3 bar. After I pumped the wheels up to 2 bar they have been good.
 
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