Please Help- 3 Rear Flats in 3 Weeks

[Connor]

Hey y'all, 

 

Bike is a 21' T7. Had the original Pirelli's on there, got a rear nail puncture (1st flat, obviously no one's fault in particular, stuff happens). Got two new tires, K60's with new tubes. A week later there is a pinch flat on the rear near the valve stem (2nd flat). Took the wheel and tire back to the shop who put on the K60's and they changed the tube for free (as they should?)...Now, only a couple weeks later after only riding on normal road and consistently checking pressure to maintain 36 PSI I found my rear tire flat again in the afternoon after riding to work that morning (3rd flat). I filled it up and the air is coming out from the valve stem again, similar to how it did with the 2nd flat. I called the shop and they said "it's no longer our problem, it is not an issue of installation, it must be tire pressure, how it is being ridden, or something else, and that it wasn't our fault the first time either, it was simply our goodwill to do that for you." 

 

Please if you have experience or knowledge on this, enlighten me on why this might be happening, what I can do (taking it to a different shop tomorrow) now or in the future. I really do not want to ride around constantly worried that somehow I will keep getting a flat tire. 

 

Thanks in advance for any wisdom or help you can offer. 

[AZJW]

Pretty strange that the leaks seem to be associated with the valve stem x 2.  When you have the tire off, do a really thorough inspection of the rim, especially in the valve stem area. File down any burrs or sharp edges and put some duct tape on any blemishes.  Might also try another brand of tube ( what are you currently using? ) plus a heavy duty tube might be in order.

 

Your tire shop certainly doesn't seem to want to be helpful a second time around, not really conducive for repeat business.   Let us know what you find.

[Connor]

24 minutes ago, AZJW said:

Pretty strange that the leaks seem to be associated with the valve stem x 2.  When you have the tire off, do a really thorough inspection of the rim, especially in the valve stem area. File down any burrs or sharp edges and put some duct tape on any blemishes.  Might also try another brand of tube ( what are you currently using? ) plus a heavy duty tube might be in order.

 

Your tire shop certainly doesn't seem to want to be helpful a second time around, not really conducive for repeat business.   Let us know what you find.

Thank you for the response. The truth is I am not sure which tube the shop put on. They advised me against a heavy duty tube because of "increased heat on highway and road conditions which can lead to early wear on the tube" (ironic)...I have a new standard tube from Cycle Gear to get put on tomorrow. I will hopefully be right next to the mechanic tomorrow morning and we will closely inspect the wheel (which I feel like is the only reasonable culprit at this point)..

[Canzvt]

So...tubed wheels/tires where there are no other drilled holes in the rim (for bead locks or similar, not spoke holes) usually ALWAYS leak around the stem, as that is the only place the air can exit the wheel assembly (unless the tire is obviously damaged). If you are not repairing this your self, take it to a shop that will allow you to watch them remove the tube or at least show it to you after they pulled it, and see where it is damaged. If it was an installation pinch (yes I have seen stellar dealers still pinch a tube on installation...) or something in the tire, then you have knowledge on what to do next.

There is some truth to heavy duty tubes heating if only doing highway miles, but that can usually be managed with weight/tire pressure/speed. If you do any off-road, I would recommend a decent heavy duty tube to minimize pinch flats in rocky terrain.

[Connor]

4 minutes ago, Canzvt said:

So...tubed wheels/tires where there are no other drilled holes in the rim (for bead locks or similar, not spoke holes) usually ALWAYS leak around the stem, as that is the only place the air can exit the wheel assembly (unless the tire is obviously damaged). If you are not repairing this your self, take it to a shop that will allow you to watch them remove the tube or at least show it to you after they pulled it, and see where it is damaged. If it was an installation pinch (yes I have seen stellar dealers still pinch a tube on installation...) or something in the tire, then you have knowledge on what to do next.

There is some truth to heavy duty tubes heating if only doing highway miles, but that can usually be managed with weight/tire pressure/speed. If you do any off-road, I would recommend a decent heavy duty tube to minimize pinch flats in rocky terrain.

Thanks for the info! All good stuff to know...Do you think its possible that it was an installation issue despite it being two weeks past the install (few hundred miles?)...Obviously we should know more tomorrow as I'll ask the mechanic to let me watch or at least inspect. Part of me is just trying to figure out if it's the shop's fault, a faulty part, or something I may have done. Mostly I just want to be able to ride with some peace of mind. 

[Connor]

7 minutes ago, Canzvt said:

So...tubed wheels/tires where there are no other drilled holes in the rim (for bead locks or similar, not spoke holes) usually ALWAYS leak around the stem, as that is the only place the air can exit the wheel assembly (unless the tire is obviously damaged). If you are not repairing this your self, take it to a shop that will allow you to watch them remove the tube or at least show it to you after they pulled it, and see where it is damaged. If it was an installation pinch (yes I have seen stellar dealers still pinch a tube on installation...) or something in the tire, then you have knowledge on what to do next.

There is some truth to heavy duty tubes heating if only doing highway miles, but that can usually be managed with weight/tire pressure/speed. If you do any off-road, I would recommend a decent heavy duty tube to minimize pinch flats in rocky terrain.

Sorry one last question...can you be more specific about how to manage having heavy duty tubes like you said?

[Canzvt]

4 minutes ago, Connor said:

Thanks for the info! All good stuff to know...Do you think its possible that it was an installation issue despite it being two weeks past the install (few hundred miles?)...Obviously we should know more tomorrow as I'll ask the mechanic to let me watch or at least inspect. Part of me is just trying to figure out if it's the shop's fault, a faulty part, or something I may have done. Mostly I just want to be able to ride with some peace of mind. 

Yes, it is possible, unlikely with that many miles, but possible for sure. Depends upon how it was pinched/folded/etc. 

[Canzvt]

4 minutes ago, Connor said:

Sorry one last question...can you be more specific about how to manage having heavy duty tubes like you said?

I think you said you are running K60's, which don't flex that much in the sidewall, so your problem is minimized just by running this tire. Keep an eye on temp. (I run those cheap chinese pressure senders on all my bikes, as it lets me know pressure, but also temp) Your rear should get warm on a hot day, but not too hot to touch. If it is really hot, increase air pressure or decrease load and slow down (I know, the last one sucks...). Tire heat is a function of flex in the tire, and differential movement between the tire and tube.

[Redbikejohn]

A pinch flat often has two small nicks in tube hence its called a snake bite in some circles.   A single nick/tear will be more down to a tyre lever pinching tube.  Its entirely possible the shop is not great with tubes as the majority of bikes are tubless nowadays. 

Get them to check rim tape. Not sure with the 700 but know the 660 had small dimples on the end of the spokes that used to wear though rim tape. More an issue with higher mileage though. 

 

[Redbikejohn]

Oh and yes a tiny nick can spread and open up later.

[Connor]

*Update…the tire is getting a new tube put in now. You can see the two tears in the tube in the photos attached (not the photo with the little bit of green slime, that is the previous flat for reference). 
 

The mechanic thinks that maybe the tire/wheel is spinning? I hadn’t heard of this concept but apparently it happens with dirt bikes a lot. So it appears that maybe neither were pinch flats? 
 

He is putting on an extra rubber grommet I guess to help give flexibility to the tube so that it does not tear if things spin. Another idea I had not heard of. 
 

Looking at the photos, anyone ever see anything like this?? It seems to be in about the same place on both occasions. 
 

Would really appreciate some experience and wisdom on this, especially in terms of how I can prevent this in the future. 

 

Thanks!

[Connor]

Also side note. Mechanic said the wheel and tire look perfect. Nothing on either that would lead him to believe that is the cause of the problem 

[Redbikejohn]

I've had tyres spinning on my race bike when using low pressure old moouse.   There is no way, absolutely no way a road tyre at 36 psi is going to spin in normal use.  To me it looks like kak handed fitting in second pic and poor quality tube delamination of valve in first.

Edited August 24, 2022 by Redbikejohn

[Connor]

2 hours ago, Redbikejohn said:

I've had tyres spinning on my race bike when using low pressure old moouse.   There is no way, absolutely no way a road tyre at 36 psi is going to spin in normal use.  To me it looks like kak handed fitting in second pic and poor quality tube delamination of valve in first.

Thanks for the response! Sorry can you explain a little more about what you mean with those two explanations?

[Canzvt]

Hmmm. So the rim and tire both look great. That's good. Does the rim have the little ribs/teeth on the tire mating surface? Just asking as if it doesn't then the rim may be incorrect. These little ribs/teeth/serrations grab onto the tire when properly seated.

 

Do you use your rear brake hard? Do you off-road it, or mainly street/gravel?

 

If it has the ribs, and you are not on your rear brake hard, I'm going with @Redbikejohn's opinion.

 

The only other possible solution is that when the tire was fitted they used COPIOUS amounts of tire lube (sometimes required with K60's...) on the bead surface and it slipped as soon as you loaded it in torsion (usually a hard braking maneuver as the T7 can't generate that much torque from its engine), causing the tire to rotate on the rim, and hence causing the failure.

[Connor]

14 minutes ago, Canzvt said:

Hmmm. So the rim and tire both look great. That's good. Does the rim have the little ribs/teeth on the tire mating surface? Just asking as if it doesn't then the rim may be incorrect. These little ribs/teeth/serrations grab onto the tire when properly seated.

 

Do you use your rear brake hard? Do you off-road it, or mainly street/gravel?

 

If it has the ribs, and you are not on your rear brake hard, I'm going with @Redbikejohn's opinion.

 

The only other possible solution is that when the tire was fitted they used COPIOUS amounts of tire lube (sometimes required with K60's...) on the bead surface and it slipped as soon as you loaded it in torsion (usually a hard braking maneuver as the T7 can't generate that much torque from its engine), causing the tire to rotate on the rim, and hence causing the failure.

Unfortunately I had to be at work when he changed the tube, so I do not know if the little ribs/teeth are there....I wouldn't say I slam on the rear brake, and in general use both brakes progressively. I have been on road 95% with maybe 5% easy going gravel...If we go with RedbikeJohn, is the solution simply, find a better tube and be perfect on installation? 

 

Sidenote: I just got the bike back home after re-fitting the tire. He used soap and water when setting the tire, I am not sure what the other shops did. He added this little rubber grommet on the valve stem that the nut screws onto instead of screwing all the way down to the rim. He said Honda does this sometimes, and that it is meant to flex if the tube is pushed or pulled so that IT gives a little and the tube/valve does not get pulled into a tear (I had never heard of this idea)...He also marked the tire where the valve stem is so that we can keep an eye on it to observe any possible slipping...

 

Really just been a hassle. I rode the xt660z in Europe for 17,000 miles through rough off road and countless highway miles using k60's for most of it and NEVER had a flat. My hope is take the T7 off road A LOT, but this just makes me so cautious (I recognize it's not the bike). 

Edited August 25, 2022 by Connor

[Hollybrook]

Since both failed in the same way, I'd suspect a bad batch of tubes or poor installation. 

 

Based on the location, I think the tube was twisted in relation to the rim, putting sideways stress on the joint between the tube and the valve.  Did they use talc in the tire to let the partially inflated tube settle in a position of low stress? 

Edited August 25, 2022 by Hollybrook

[Canzvt]

13 hours ago, Connor said:

If we go with RedbikeJohn, is the solution simply, find a better tube and be perfect on installation? 

 

Sidenote: I just got the bike back home after re-fitting the tire. He used soap and water when setting the tire, I am not sure what the other shops did. He added this little rubber grommet on the valve stem that the nut screws onto instead of screwing all the way down to the rim. He said Honda does this sometimes, and that it is meant to flex if the tube is pushed or pulled so that IT gives a little and the tube/valve does not get pulled into a tear (I had never heard of this idea)...He also marked the tire where the valve stem is so that we can keep an eye on it to observe any possible slipping...

 

Really just been a hassle. I rode the xt660z in Europe for 17,000 miles through rough off road and countless highway miles using k60's for most of it and NEVER had a flat. My hope is take the T7 off road A LOT, but this just makes me so cautious (I recognize it's not the bike). 

Better tube, and use the guy who did your latest installation. Seems to know his stuff. I don't think you will have a problem from here. Good luck!

[tenerecanada]

On 8/25/2022 at 12:34 AM, Connor said:

instead of screwing all the way down to the rim

I always screw the nut against the cap. I wonder if tightening the nut against the rim attributed to the failures. 

[Black99S]

Baby powder the tube so it can move.

[roygilbo]

On 8/26/2022 at 9:29 AM, tenerecanada said:

I always screw the nut against the cap. I wonder if tightening the nut against the rim attributed to the failures. 

So your valve stem is not tight to the rim with the nut?  Can you take a pic?  The tube box always shows the nut tight to the rim.  Hmmm...

[tenerecanada]

11 hours ago, roygilbo said:

So your valve stem is not tight to the rim with the nut?  Can you take a pic?  The tube box always shows the nut tight to the rim.  Hmmm...

At work now so no picture, but here is an article written by a well known guy in the industry, picture and explanation is item #2 on his list. I'd say the high torque/horsepower of the T7 is mimicking running low pressure in tires as the article states, preventing the stem from having any free play and causing his issues.