The Mystery Flat

Flat tires are an inconvenience that I have not experienced for over a year, since I got Schwalbe tires on Oma and Betty Foy.

Sliced Tire

Sliced Tire

The cheap tires that came on Mr. Dottie’s Jamis, on the other hand, have had several flats in their lifetime. The most extreme flat happened last week – a clean slice straight across the tire itself. He went back to try to find the culprit, but did not see anything that could have sliced a tire, other than a grated bridge, but that seems unlikely. The problem cannot be a defect with the tire itself, because the tube was also sliced. Any ideas? Has this happened to anyone else?

Poor tire

Poor flat tire

As an aside, I must note that his Jamis frame is obviously too small for him, and the larger vintage Raleigh frame he recently built up is a much better and more comfortable fit. I don’t know why the bike shop sold him that size – they even had to special order it because the size was not in their inventory. We had no bicycle knowledge at the time, and we followed their recommendations. Boo.

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49 thoughts on “The Mystery Flat

  1. Scott says:


  2. Erich says:

    Dunno about the flat, but selling undersized bikes seems commonplace nowadays. The whole lotta seatpost thing is hip or something, and most people think their crotches shouldn’t come close to the top tube, which is why compact frames like the Jamis have become popular.

    It takes a lot of convincing to make a new rider understand just how big their bike frame needs to be, and I think bike shops would rather just sell bikes quickly, no matter how they actually fit the rider or intended purpose.

  3. Oh, that’s one bad tear. Get that man Schwalbe tubes and tires with a kevlar belt, STAT! : )

    Maybe I am just particularly susceptible to the placebo effect when it comes to tire, but the 2 times I have ridden on a bike with non-kevlar tires this year, I got a flat each time. Never got a flat on either of my tires with kevlar, and I have taken them though some pretty wacky terrain.

    • dukiebiddle says:

      I don’t think even Schwalbe or kevlar could have prevented whatever the hell happened to that tire.

  4. pomocomo says:

    This definitely looks like a slashed tire, especially if the slice went through the tube, but I guess not if it happened while he was riding it. Schwalbe or not, whatever he ran over was going to have that result. Good tires are no replacement for tools and tire changing skillz.

    Question about the size – did Greg always feel that the bike was too small, or is it an understanding that he grew into, so to speak? I feel like ideal fit can change over time as your body perceives comfort. I’m still tweaking my fit on the bikes years after I’ve had them.

    • Mr. Dottie says:

      I didn’t feel that it was always too small, but I also didn’t have a good comparison for fit. After receiving many comments about the height of my seat, I noticed the seat post was raised higher than the maximum limit stamped on the post and knew the frame had to be too small for me. I lowered the seat to the maximum limit line on the post and continued to ride without any problems.

  5. gwadzilla says:

    I was riding some unmarked dirt trails on the Maryland DC border… it is hardly even a park… just a swath of land with unmarked unsanctioned trails

    maybe less than a mile loop
    I was running different little loops when I realized the time
    so I pointed my way out of the woods when I had a double flat

    A double flat?
    hmmm…. that seemed suspect

    I told my brother the story
    then guess what
    when he went to check out the same set of trails he double flatted

    he retunrned with a police officer and a metal detector
    they found a row of nails on a board hidden beneath the leaves

    there were several of these

    a trap for bikes

    but what about the dogs or the children that may use these trails?

    the cops did nothing

    that “do gooder” is an asshole and deserves a welcome mat made of similar design

  6. Steve A says:

    If the bead has failed, a blowout similar to that could happen. I had such a failure on a cheap Wallyworld tire. A failure in the lip at the seal led the tire to fail whenever it was pumped up. Sometimes it would hold air for a while and then go suddenly. The last time, the tire ripped as well. I then got the message. Once the tire goes, the tube will fail pretty much instantly, and at the same spot.

    It seems unlikely that such a big tear would occur from road debris without damaging the rim. Make sure Mr Dottie carefully checks the rim whether the replacement is inexpensive or exotic. If the rim’s OK, he’ll be OK. You may never know for sure, but check that rim carefully!

  7. Steve A says:

    PS: I swear by Continental GP 4 Season tires for my commute, by the way. Nearly 3000 miles on them before I got a flat. I think they’ll last 5000 miles before I have to replace them from wear.

  8. Steven Vance says:

    I don’t think an open grated metal bridge can do this. The grates aren’t sharp and the distance between each grate is too short that your tire rests on 2+ grates at any one time while rolling (unless you had a very flat tire).

    Did the flat happen while riding or after being parked?

    I finally picked up a real tire, a Michelin All City for commuting, with a Kevlar belt inside. It replaces the Kenda Kommuter which had no protection (it was also kind of worn out…eh).

    • Mr. Dottie says:

      I was riding when it happened. I was approaching an intersection and when I entered the intersection I heard a quiet “whoosh.” The tire when flat immediately. The tube was sliced as well; both the tire and tube were a clean cut with no threads exposed.

  9. Jeez, that seat looks high. Wait, I’ve been riding a Dutch bike for 3 months. I’ve forgotten what it’s like to stoop like that.

    Some bike shops will sale you anything. Don’t patronize and don’t recommend. You’ll do better, next time.

  10. Zweiradler says:

    Wow, I have never seen anything like that. But I have witnessed twice that someone’s tyre burst with a loud bang without warning.
    I’m using Schwalbes, too, but only with the lighter RaceGuard protection. Fortunately I know how to fix a flat. I have to do it approximately once every 1000 km. :)


  11. 2whls3spds says:

    How tall is Mr Dottie? I have to chuckle a bit at the Mr. Dottie moniker, I have the same problem, but answer to Mr. Rhonda! LOL (I also tell people I sleep with the boss :-D )

    I suspect a couple of things on the frame, they wanted to make the sale and it is the largest frame available. I have a helluva time finding stock frames that fit. I ride a 65cm old style road frame, or a 25.5″ upright frame. With the current crop of “compact” sizing frames it is very difficult to get one anywhere near the correct size, most seem to stop at 57cm-60cm range.

    That tire “cut” looks almost like a casing failure, are the threads clean cut or torn (hard to tell from the picture. It is possible that he rolled over something a while back, weakened the tire and it waited until now to blow out.


    • dottie says:

      The threads in the tire are clean cut and the tube is also cut in the same way.

      There are two larger frame sizes available for the bike, so I don’t know what the deal was. It is a good shop, generally.

  12. E A says:

    Eeek! A blowout? Hopefully you weren’t too far from home.

    So you’re selling this bike? What size is it and how tall are you?

    Different frames have different sizing (geometries). I got fitted to my commuter recently and learned a few things that surprised me! We’ll have to chat. A good commuter fitting can go a long way toward comfort and reducing injury, too.

    • Mr. Dottie says:

      I was riding to an appointment from Halsted and Chicago. I got the flat around Halsted and North and walked 2.5-3 miles to make the appointment. The weather was nice and I knew I wouldn’t be late, so I opted to walk instead of putting the bike on the front of a bus.

      I’m 5’10” and the Jamis frame is 19.5.” The larger sizes for the frame would have been 21.5″ and 23″. My current project bike is around 22.5-23.5″.

      • dukiebiddle says:

        I’m 5’10” and 22.5″ is definitely too big for me. I have a 22″ (56cm) full frame road, and I’m stretched out too much by a good inch and a half on top. Awww, people are like snowflakes. Each one is a little different. Barf. ;-)

        • Jon says:

          A lot of those older Raleighs have parallel 73 degree head tubes and seat tubes. As the size goes up, the top top tube remains the same length (about 22-1?2″, IIRC). Thus, a person 5’10” tall can ride the taller frame, with no reach problem. Taller riders may feel a bit cramped, though.

      • Johnny says:

        I have a 19.5 inch Coda, and I’m about your height. Mine fits great though, but dang I have short legs. :)

  13. Ghost Rider says:

    I experienced that…after running over a discarded beer bottle unseen at the side of the road. Split the tire and tube clean in two!!!

  14. 2whls3spds says:

    If I had been fitting you for the commuter I would have probably put on the 21.5″. When using a MTB style frame you go small for off road use and go larger for road use.

    I am 6’2″ with long legs and arms. I have a 21.5″ Giant that I ride as a expedition tour bike, but would be better off with the 23″, if I could find one. Unfortunately too many bike shop employees are un/under educated. There is one shop in my area that I refuse to frequent because of this. They only want to sell you the latest carbon fibre trinket and have no interest in whether what you are buying fits or is suitable. The other doesn’t stock what I buy either but they are willing to order anything I ask for and occasionally ask my opinion on what works best for commuting or cargo use.


    • dottie says:

      I remember when that happened to you – awful! I’m surprised looking at the post that I did not comment. I did not fully understand how important comments are until I started a blog myself :)

      • miss sarah says:

        The worst part was that tyre was a special order since it’s only 26″. It took over a month for the right one to come in. And it was just so… MEAN. I hope that person gets hepatitis! And whoever it was that hurt Mr. Dottie’s bike, too!


  15. Lemony says:

    to you? hmmmmm!

    • dukiebiddle says:

      Heh. Well, yeah. I may be irregular, but I’m really not freakishly built, and that chart isn’t even close for me. C-C, or C-T? Nothing about top tubes? Gender?

  16. Lemony says:

    Just above chart:

    Related article: Adjusting Your Bike For Proper Fit

    • dukiebiddle says:

      Okaaaay. I just read that too, and it was full of errors. It presumed all bikes have traditional geometry when only a small minority do today, it said nothing about C-C or C-T, nothing about the importance of top tube length, nothing about women having a shorter torso to leg ratio. Don’t get me wrong, those instructions would be fine for someone buying a vintage bicycle and didn’t need it to fit too well, but it is woefully inadequate in today’s bicycle market. Bicycle sizing is quite complicated, and a pap chart is only a starting point at best.

  17. Charlie says:

    This is a classic ninja ice blade scenario. Ninja creates a razor shaped ice cube and places it on the road, it slices the tire and the heat from the tire melts it. No evidence, ninja strikes again.

  18. Elisa M says:

    that is one serious flat! Wow. I used to have major flat issues, but got some Gatorskins and now can run over anything with no problems.
    My first “big girl” bike was sold to me at much too small of a size. Very frustrating! They also sold me a helmet that was too big…I won’t shop there anymore.

  19. Dean Peddle says:

    Another vote for Gatorskins here also. I’ve been riding them for years (700×25) and I never get flats riding a 75km round trip commute to work. I have a set on 4 bikes only missing my Dutch and fold up bikes due to they don’t make them that size (note: Shwable Marathons on both bikes have never flatted either). I even purchased a set of Gatorskin Tubulars and I’ve rode them for 2 seasons also without flatting.

  20. Another vote for Gatorskins and Schwalbe tires.

    As for the flat. It looks like an under-inflated tire hitting a sharp corner (could be metal grate.)

  21. […] and Her Mystery Flat by Bike Shop Girl Last week Let’s Go Ride a Bike talked about a mystery flat that happend on Mr. Dottie’s bike.  The cut in the tire is pretty intense and almost across […]

  22. BruceH says:

    I had a flat very similar to that once. My best guess was old tires and glass.

  23. BruceH says:

    Looking more closely at the picture, notice there are two parrallel cuts to the tire. I’m thinking it was the metal grate, plus the age of the tires and perhaps improper inflation.

    • Mr. Dottie says:

      There is a single cut on the tire and the other marks are from wear/stress. My LBS said the wear/stress marks are normal.

      The bike and tires were purchased May 2008 and the tire pressure was approximately 95-100psi when I began the day.

  24. MarkA says:

    Going totally off-topic here can I say how handsome Mr Dottie looks in this picture – you two are like the model faces of ‘how to look good cycling’! ;-)

    Oh, and re the flat I am going with the Ninja theory – seems totally plausible to me.

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