Should I service / replace / do nothing to my spokes which have done about 21000km before the next longer trip?

Question

I'm planning on doing a 2000km trip (through Spain and Portugal). I'm wondering if I should do anything to my spokes before the trip.

The spokes have accumulated the following distances

1. front spokes: +- 6400km (4000miles).
2. rear spokes: +- 21000km (13000miles). About 2000km ago (i.e. after the rear wheel had done 19000km) one rear spoke snapped. I only had that one spoke replaced.

I had both wheels serviced about 1500km ago (just after the one rear spoke snapped). The spokes were not replaced only the tension adjusted.

Question Should I have the spoke's serviced (i.e. check the tension) or completely replaced (given the age of the spokes and the up coming trip) or do nothing?

Details of the bike

1. mountain bike (no shock absorbers)
2. 26'' wheels
3. 32 spokes on each wheel
4. rims: mavic
5. disc brakes
6. I carry bags on the handle bar, front wheel and rear wheel

Answer 1

In my experience breaking spokes is not correlated with number of kilometres ridden, it has more to do with keeping the wheel in good repair (not warped, even tension on the spokes) and avoiding impacts.

I would inspect the wheel, or have it checked at a shop, to make sure it's in good condition, and given that I would ride it without worry. I would, however, bring a few spare spokes with me on a long tour, just in case. (They don't weigh much.) If you're checking the wheels yourself you should look for traces of corrosion at the spoke nipple (dissimilar metals in contact, so the most likely place for it to start) and check the length of each spoke for nicks or deep scratches, as from scraping against a rock or the chain getting caught on it. Assuming no apparent damage and even tension, you should be good.

I wouldn't be overly concerned about a single failed spoke, especially if it's been replaced for a few thousand kilometres without further incident. That single failure could have been a lone substandard spoke or, more likely, some localized damage like hitting a rock, getting hung up on something when leaned (or leaned against), accidentally dropping a tool on it, etc.

Note that there is no intrinsic reason for spokes to fail with use. Properly and evenly tensioned there should not be enough flex in the spokes to cause metal fatigue. (If you were fatiguing the spokes they would wear out in a lot less than 6 000 km.) If they are free of corrosion (the other probable cause of failure with age) then they should last for decades. Embrittlement should be extremely rare given the conditions under which bikes are stored and used.

I've had a couple of touring bikes on which I have put tens of thousands of kilometres. I've gone through a few wheelsets; I had to replace one after the rear wheel failed due to wear on the brake track. Those wheels had approximately 40 000 km on them, and the front wheel had never broken a spoke. (I had another wheel fail after about 25 000 km when the hub flange cracked; the spokes were fine.)

I have, on the other hand, broken a lot of spokes. Most of those can be directly attributed to abusing the wheels, for example by riding off a kerb with loaded panniers. (Or rather, doing that many times.)

I don't want to sound like a certain other user, but if you're loaded touring a high spoke count is your friend. It both reduces the likelihood of breaking a spoke in the first place and also makes it a lot easier to cope with a broken spoke if it happens.

Answer 2

If your wheel has a history of breaking spokes (many of them, just one doesn't count, especially if it was due to external damage), then you should replace every single one of the spokes and rebuild the wheel with good wheelbuilding practices. This includes high and even tension plus stress relieving the wheel. In a pinch you could stress relieve (grasp 4 spokes tightly with both hands and squeeze) and replace only those spokes that break during stress relieving, but it's better to replace all if they have been failing often.

If the wheel doesn't have a history of breaking spokes, then no, don't do anything to it. The reasoning is that a spoke that has demonstrated its longevity during actual riding conditions is better. You already know the spoke isn't from a bad batch. If you buy new spokes, chances are all of your spokes are from the same batch. With 99.9% or 99.99% certainty it's a good batch but there could be a material issue that affects all of the new spokes, and it could be a disaster if you go to a long ride with new unproven spokes. Also if you install new spokes and don't stress relieve, it's possible they will start failing. Today this isn't as likely as it was at the time The Bicycle Wheel was written since materials have improved, but it's still possible, especially if the wheel doesn't have enough spokes, if the spokes are too thin (or worse yet, non-circular cross section), or if the weight on the wheel is very large. Also rebuilding without a tensiometer could mean disaster since you don't know if the tension is right. Of course if rebuilding two wheels, you can use one of them (the one not under a new build) as a reference and by plucking the spokes checking that the tension in the old wheel and in the newly built wheel is the same. This doesn't help if you are tone deaf, and assumes the wheels have identical diameter and identical types of spokes.

In well built wheels, spokes have a lifetime in kilometers far greater than a car engine has. A stick in the spokes could damage many, obviously, but then again that's not normal wear and tear. No need to replace them based on kilometers ridden.

I'd say for your trip:

• Modern bushingless chains even without rain have a terrible oil lifetime. You may need to re-oil as early as in 800 km. Bring some oil with you, in as small container as possible, since you need only very little of it. Also few reinforced paper towels could help to wipe away the worst dirt before re-oiling and removing excess oil after re-oiling.
• Modern brakes have horrible brake pad life. I wear out my disc brake pads in about 2000 km. Bring extra pads plus tools to change them with you, or maybe if you are using rim brakes or sintered metallic disc brake pads, you could install new pads and trust in them having long enough lifetime to do the trip.
• It's a good idea to check if the chain needs to be replaced. My chains last 4500 km. Thus, if I have a chain with 4000 km in it, it would have 6000 km after the trip, maybe a little bit too much, which could result in sprocket wear and need to change the sprocket cassette too after the trip.
• Remember to pump up your tires with a floor pump before the trip since you will hate pumping with portable pumps.

Your 26" 32-spoke wheels have a spoke density equal to 700c 36-spoke wheels. That's enough many spokes that if one breaks, you can adjust the tension of the rest to have acceptable wheel trueness even for most rim brakes if you loosen up the barrel adjuster a bit. With your disc brakes it's absolutely no problem. However, if a spoke fails behind the cassette or behind a brake disc, you may not have the tools to fully remove it, but a zip tie could hold it in place to allow continuing riding. Just remember to have that spoke wrench and zip ties in your emergency toolkit.