Hello all. My wife and lovely stoker (same person) and I had the chance to get a ride in after work today. One part of the neighborhood ride has a nice decent of a couple hundred yards ending at a T bone stop. If you just put a bit of effort into pedaling you carve down this thing at 40mph b/4 having to brake for the stop sign. My wife has mentioned to me the last two rides that she could do without the high speed at decent down to the lake.
So, this time I thought I'd be a good captain and do what my wife wished and ride the brakes down keeping the speed at a level in which she feels good about. Well, it's a good thing as we had a front tyre blow. I tell you what, as funky as it was keeping the bike up on a decent with a curve at 20mph with a flat front, I KNOW I want no part of a high speed front wheel blowout!!
While changing the tube I found that the rim tape had several holes where the spoke eyelet had cut through. I keep a dollar in the bag for these types of things and was able to get home by covering the holes with pieces of a dollar bill.
What I learnd today:
1.) When you get a new set of wheels, if the wheels come with a no name rim tape take it off and replace it with some Velox.
2.) Listen to your stoker as they are always right!
3.) Never go faster on a decent than a speed you'd care to bail out at.
I've had way too many flats in my life (seems like I had a year where I couldnt get on a bike without changing a flat) on single road and MTBs. I've had a few flats on our tandem on the rear wheel that where no big deal. So, when I heard the front blow I was not alarmed. My first thought the instant I heard it was "dang just got started and now we have to stop". Then I learned that when you are decending, applying the front brake and have a front flat, control becomes a bit of an issue.
This was my first front flat on our tandem dont think I'll have another.
Originally posted by brad So, this time I thought I'd be a good captain and do what my wife wished and ride the brakes down keeping the speed at a level in which she feels good about. Well, it's a good thing as we had a front tyre blow. While changing the tube I found that the rim tape had several holes where the spoke eyelet had cut through.
Any chance you rode the front brake enough to overheat the rim to where the air in the tube expanded enough to force the cut-through of the rim strip?
I only ask in light of the description of your hill, i.e., several hundred yards with what sounds to be a good 5% or greater grade... which when combined with riding a rim brake hard enough (or conversely, longer descents with less brake lever pressure) is quite often the cause of blow-outs on tandems. I posted a fairly lengthy item on this nearly tandem-unique failure mode on this forum in the past, but it suffices to say under the right (or wrong) circumstances an overheated rim / tube will invariably surface any weaknesses in your rim bead, valve stem or rim tape in the form of a sudden and pronounced tire blow-out.
You know Mark, when I took the wheel off it was hot as heck. I did wonder if the heat did it but, when the tape was worn/punched out in several places I assumed that it happend over time. It was hot enough that you'd touch it and think "wow that's pretty hot" so, I cant say that I'm 100% sure heat didnt do it.
I dont think there is a formula for success for keeping a tandem up at speeds with a front blowout. Just have to do the best you can!?! It is a heck of a lot steadier when you keep the bike going in a straight line. We were decending down a road with a curve when ours blew. When I'd have to turn the wheel is when the front would drift wildly. If and when it happens to us again I'll just lay on all the rear brake I can (not enough to lock up the wheel though) and try keeping it in a straight line till I can stop. Oh, and it helps you yell YEEHAW.
This is one of those things that you need to mentally practice while you’re out riding by doing “what if” scenarios. In other words, what if I had a flat right now... where would I go and what would I encounter? What if a car pulled out on this steep hill?
To make sure you are mentally practicing the right things, there are a lot of things that need to happen almost at the same time to safely negotiate a stop after a front wheel (or rear wheel) blow-out which actually comprise a “trained response”.
Anyway, for a front wheel blow-out, this is what you need to remember...
a. Pick your riding line (i.e., where you can safely ride to a stop),
b. stay off the front brake,
c. guide the bike in as straight a line as possible with gentle steering inputs down your riding line, and
d. use the rear brake to carefully slow the bike to a stop.
The fine points.
Rear Braking Control: Since you’re trying to minimize the forces on the front wheel that could cause the tire to become unseated from the rim, don't "grab" the rear brake or use aggressive rear braking unless the risk of crashing is less threatening than the risk of going into oncoming traffic, off the edge of a road, etc… Braking with the rear wheel on a bike – and tandems in particular – moves the weight of the bike and rider(s) on to the front wheel as the bike decelerates and the amount of the “load” is directly proportional to how much braking force is being used.
The Front Tire: If you flat a front tire in a hard/fast turn it can get ugly. You have a short window of opportunity to “save it” when the tire first goes flat and is sitting/folded under the inside edge of the bicycle. Keeping the tire on the rim is a function of a firm rim bead on your tire. Therefore, always be sure the tires you use for your front wheel have a good, tight fit on your rims and that they are in relatively good condition with regard to the bead, tread wear and suppleness. A relatively fresh tire is more likely to stay attached to the rim even when flat than one that has a lot of miles or has become brittle from age/ozone/sunlight/dry air.
Front Tire vs Rear Tire Flats: In reality, flatting a front tire happens far less often than flatting a rear, if only due to Murphy’s Law… the rear wheel is technically more challenging to change. Seriously, the heat-induced tandem blow-out is normally something you see with a rear tire since most (but certainly not all) cyclists “ride” their rear brake on long hills and modulate speed with the front brake since it feels and is more responsive than the rear brake. Also, cyclists tend to steer the front tire around (or even pull it up) to clear obstacles that the rear tire gets ridden through or over. Finally, the rear tire carries 60% or more of a bike’s total weight AND is the sole point where power is transmitted from the bicycle rider to the ground which means it wears out more quickly and is more apt to puncture when it contacts a sharp object.