Monday, April 26, 2010

Flats Flats Flats FLATS!!!!!

So I posted yesterday about the Monster Cookie ride in Salem, OR. I had several flats that day - 4 on the ride and another by the time I got home - the tire was flat again. Only one was a "real" flat. The first one was clearly a puncture of the tire and tube. OK, I can live with that - fix and off I go. 

The rest of the flats though were "mystery" flats that I could just not figure out. Flats at 20 miles, 40 miles, 55 miles, at the finish, and then at home. As I had my sunglasses on and I was out on a ride, I did not dive deep into the diagnosis, I just threw tubes at the thing and rode on. When I ran out of tubes by the third flat I patched and replaced...until I got home and the tire was flat yet again.


I decided to start with what I have changed - I recently (as in just a few days before the ride installed velopulgs on my two front trike wheels - the ones that flatted all day. I already had them on the back wheel for almost a year, and I have them on three other bikes that run velocity rims and on a spare set of velocity wheels for the F5 high racer. 

I had noticed on the ride on all flats after the first one that the hole I found was on the inside of the tube - where the tube hits the wheel - as opposed to the tire. The first few times I figured in my changing I must have accidentally let a tiny rock get into the tire before I mounted it... but there never was one.

Turns out the rims were causing the flats. I have run Veloplugs on the back tire since I got the trike. Turns out both my front rims (all three are Velocity Aeroheats) have a thin ridge that runs down the center of the rim. I had not paid much attention to this, but it looks like that little rim is enough to act like a ton of 'lil exacto blades to slowly cut the tube to ribbons. I submit the following for evidence:

The first pic is my rear tire, which did not flat and never has. I took it off to compare the rim surfaces. You can see from the pic that it is pretty smooth.

The second pic is one of the front wheels. You can see a thin "ridge" that runs around the surface of the wheel right between the Veloplugs around the circumference of the wheel. It is raised just a bit, and is not particularly sharp or anything. When I installed the Veloplugs I really did not even pay any attention to it.

I aired up all of my tubes I burned through to super large size and they all had the same thing - the dark lines you can see in the middle there are thin cuts running all the way around the inside from those ridges. Needless to say all the tubes are shot and not fixable - a few are almost cut like oddly spaced perforated lines all the way around the tube.

Needless to say it looks like I will have to go back to the 'ol tape on these rims.

I suppose this is an "easy fix" you might think - just put in some rim tape and be done with the 'plugs. Well I like the plugs - they make installing tires a lot easier and they are nice and clean. The minimal instructions indicate "plug and go" simplicity which they should be. BUT - if this is a faulty wheel situation, or worse, something that could happen on wheels without baby butt smooth insides - real trouble could ensue from flats caused my the wheel itself and not an external source.

I flatted on the trike - no biggie I just shrugged and pulled over to a stop. One of my flats was very rapid and I was hitting close to 30MPH at the time. NOW, had I been on my F5 doing 30MPH and had a rapid front flat - that could cause a wreck.

I have contacted the folks at Velocity USA to get their take. I deflated and took a look at all of my other Velocity rims - all are smooth with no pronounced ridge.

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