12 mars 2009

Tire Rotation the Right Way

Alan Ardizone

This question often comes up : Should bike tires be rotated like car tires to extend their life ?

No.

See you next week !

Oh, wait, you want an explanation ?

What I recommend is to keep the rear tire on until the brownish casing starts to show through the black tread, or nearly so. Then put the front tire on the rear wheel and install new rubber up front.

If you don't move the front tire, it'll probably rot on the rim before it ever shows signs of serious wear.

So that's smart rotation. What's not smart is rotating a half-worn rear tire to the front in an attempt to keep both tires on the bike until they simultaneously wear out. Don't make it easier to lose control because of a front-tire flat or blowout. Have your best rubber on the end of the bike that has the most to say about staying upright.

Besides plain ol' wear, there are a couple of other compelling reasons to retire a tire.

First, a cut too big to be booted.

A cut through the tread and underlying casing can be patched, or "booted," if it's small and fairly straight. A cut that's jagged or curved is probably a blowout waiting to happen, so chuck the tire if it looks that bad.

You can boot a cut from the inside with various things. I like a tube patch or tough strapping (filament) tape. I use a couple of layers and cross the fibers, kind of like the bias of the casing itself. Strapping tape is strong, and the fix should last the life of the tire.

Second, rubber that has dried like a prune on a Phoenix sidewalk.

Riding on a dry, cracked tire, no matter how little tread wear there is, is a bad idea. It'll grip about as good as eggs in a Teflon pan. (I know, I know -- mine stick, too.)

Check for dryness when the tire isn't inflated. Pinch the tread and look for telltale cracks. Scrape your fingernail along the sidewall and watch for powdery residue.

Tires dry out from too much sun exposure, like I'm starting to do. And from ozone exposure when they're stored near electric motors or L.A. smog. A dry climate, like we have here in Colorado, will do it too.

I've been told that Armor All will prevent drying, but I'd be wary of putting anything that slippery near rims and brake pads. Remember, these are just bike tires, not works of art. Replace them if they're questionable.

Caution : For you gals and guys who race, never do it on a compromised tire. A blowout in race conditions could put your life on the line (and the lives of riders around you).

If you can't race on good tires, stay home and earn enough dough till you can afford them. Sketchy equipment cannot be tolerated in the peloton. If you're truly responsible you'll stay out of any group ride when your bike isn't sound.


11 avril 2013

The question from Greg :

What's the best strategy for rotating tires for maximum wear and safety? Here are the options I'm wondering about:

1) Starting with 2 new tires on the bike. When rear wears out, replace it with a new one. When front wears out, replace with new (i.e., no rotation).

2) Starting with 2 new tires on the bike. When rear wears out, put front tire on rear, put new tire on front. Repeat indefinitely.

3) Starting with 2 new tires on the bike. When rear tire wears about half way or so, switch with front. Try to get both tires to wear out so they both need to be replaced at the same time.

Any insights will be helpful. I have a cycling buddy who always does option #2. Recently, I've been using option #1. Which is best? Or none of the above?

RBR Crew Tire Rotation Practices and Opinions

Now, let’s run through what the RBR crew think about this. Coach Fred was on road at the time, so he kept his answer brief. I’ll start with my response to Greg.

John Marsh’s Approach
I typically follow Option 2, for a couple of reasons:

1. The rear (obviously) wears out faster.

2. The front lasts much longer, typically, and to me is more important re: safety in terms of fewer flats, gripping in turns, etc., and therefore, I prefer to keep fresher rubber up front.

Rear flats, even at speed, usually allow the rider to maintain control of the bike. Front flats can be quite a different story, so giving yourself the best chance to avoid them by keeping fresh tires up front is, to me, the best approach.

I'd say whatever works best for you, Option 1 or 2, go with that. Though Option 3 sounds unsafe. Putting worn rubber up front could be dangerous, for the reasons above.

Coach Fred Matheny’s Approach
I start with two new tires, then when the rear is worn I toss it, move the front tire to the rear and put the new one on the front.

Coach David Ertl’s Approach
Regarding tire rotation, I do #2. Because the rear wears faster and needs to be replaced faster, I put the new tire on front and move the front to back. My main reason is that if I leave the same tire on front it may get old, brittle, cracked long before it wears out. So by moving it to the back it can wear out before it gets too old.

The only drawback to this is if I change tire brands or colors. I usually stick with the same tire type, but if I switch I change both so they match. But then I resume the same front to back rotation.

Coach Alan Canfield’s Approach
Option 1 is my general approach because it takes less work, but Option 2 is preferred for several reasons:

•Front tires can last so long that they actually start to dry rot on the sidewalls, making them subject to blowout or easier flatting. I recall one instance where I nicked a large rock on the side that cut the sidewall of my front tire. It was nearly an immediate blowout and if you've experienced this, you know it can be hard to stay upright. I think a newer tire up front might not have been cut.

•Another good reason to rotate from front to rear and put the best rubber on the front is to inspect the wheel and rim strip, if present. Rim strips can move over time, and it's a good idea to inspect them to ensure the spoke hole is still fully covered. I actually identified cracks in my front wheel when changing a tire and subsequently the rim strip. I remember thinking "Why is there daylight showing through this rim?"

Regarding Option 3: There are several reasons why putting old rubber up front is a bad idea.

•You will certainly be more prone to front flats with the thinner rubber up front. This could have secondary affects if you crash when getting a flat that could have been avoided with a good tire.

•While control may or may not be affected depending on the type of tire and whether it has a softer rubber compound on the sidewall, you might experience a real or perceived change in handling and/or rolling resistance. As the rear tire gets "squared off," it changes the contact patch from a longer, linear patch to a more rounded patch. This could affect traction in turning as you lean the front wheel over.

Be sure to get the most out of each set of tires, while balancing wear with the safety and the convenience of reduced flats. One of my trusted wrenches says "More than half of your flats will occur in the last 25% of rubber." I like to ride my bike and not change flats, so I change my tires before the wear indicator would suggest.

Jim Langley’s Approach
I go with Option 1 and argue that the other 2 options offer no gain and can cause more problems.

The way I look at it is that you are going to wear out your tires eventually no matter what you do. If you go to the trouble to put the front tire on the rear, you just wear it out more quickly, so you haven’t really gained anything. Plus, changing tires always creates the risk of flatting during removal and installation – even if you’re an expert at it.

Some tubes have seams that are just waiting for a chance to fail, and removal, installation and deflation/inflation are things that make that happen. Tire rotation involves removing and installing two tubes so it’s double the risk of flatting versus just changing out one worn-out tire.

For all these reasons, I just replace tires as they wear out.

I know you can get around some of my issues by following a set schedule and rotating them before they wear too much, but I’d still argue that you aren’t gaining anything and you’re doing needless maintenance that can lead to flats you wouldn’t have had if you left the tires alone.

I’m mainly coming from a mechanic’s perspective following the rule, if it ain’t busted, don’t fix it, and the other rule that tires will wear out in the same amount of time whether you leave them where they are or you move them around. You only get so many miles out of any tire. So if you rotate and I don’t, we’ll both get the same mileage out of both of our tires.

Regarding Option 3: Putting a worn rear tire on the front is asking for trouble. In the back a flat won’t usually be much of a problem. But in the front it can cause a flat that then causes you to crash.

In short, I would rather use the time to ride and only replace tires that are worn, front or rear.


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