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For the last ten years, I have been riding a mountain bike (Specialized/Rockhopper), and often rather wildly, through rough terrain (roots, jumps, ruts). I am around 110 kg (240 pounds).
As a consequence, my back wheel often starts to wobble after some dozen rides, typically coming with the loss of one or more spokes. My cure so far was to bring it in the shop, and get the spokes replaced, and the wheel was true again. There are rarely issues with the front wheel, but it happened too.

However, in the recent two years, I have only ridden on pavement (roads and bike trails), and it still happens a lot now. I have the feeling that the back wheel is just beyond its life, but I'm not sure, and I really don't have the knowledge if this makes even sense.

The question is, what is the best/right thing to do now:

  • I can keep going to the shop every other month, and get the rear wheel trued-up. Costly in the long term, but works.
  • I can ask them to replace the rear wheel. A lot more cost, as the cassette needs to be transferred, and this would open a can of worms, the cassette is over ten years old and maybe should be replaced too, and when doing this, the derailleur, the chain, and the front sprockets also should be replaced, so I'm quickly nearing the price of a new bike. It might still be the best option, though.
  • I can buy spokes and a spoke key - should be cheap - and learn to fix that myself. That is at the moment my favorite idea, but I am not sure it solves the issue.
  • I can remove all spokes, to see the true form of the rear wheel (which is probably badly bend). Then I bend it back to about straight (or replace it), and add all spokes back in. I don't know if that approach makes any sense; it sounds like a lot of effort.
  • I can toss it and buy a new bike

I am looking for someone experienced with such repairs, who is not interested to make the most money off me, to tell me what is the best approach. What makes sense?

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    Figure out why the wheel is losing it. – Daniel R Hicks Mar 14 at 18:35
  • Another option - learn to replace spokes yourself and true your own wheel. It's not hard. I have a wheel that has had ~half its spokes replaced over time, and the rate of replacement has dropped to zero lately. – Criggie Mar 14 at 20:46
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    How many spokes are there in your rear wheel? At 110 kg you may be pushing the safety margin on this wheel. Personally I'd want 32 spokes as a minimum, with 36 being ideal for us larger types. – Criggie Mar 14 at 20:48
  • If you're regularly breaking spokes then I would suspect that either the spokes are poor quality of there is something wonky about the hub. – Daniel R Hicks Mar 14 at 21:31
  • "Replace the rear wheel, a lot more cost" - my local shop sold me a replacement second hand wheel for less than a new freehub, maybe an option? – Caius Jard Mar 15 at 17:15
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Unless the cost of a new wheel that's suitable for you plus any other repairs the bike might need is greater than what the bike is worth to you, than the answer by far is get a new wheel.

Folks in your weight range who ride a lot tend to need an especially strong and reliable aftermarket wheel. The stock advice is to get a handbuilt one. The reason for this is that a good handbuilt wheel has a number of processes done to it that make spoke breakage and loosening much less of a factor, to the point of never occurring if everything goes right. But that sort of wheel is usually around twice the price of a replacement wheel that at least has the fundamentals covered for what you need (strong rim). A conscientious mechanic installing that sort of wheel on your bike will see that you would be best served by handbuilt and be able to do some of those steps on a cheaper machine-built wheel without adding a bunch of time. (The big example being making sure the spoke tensions are high and balanced, and stress-relieving them).

The cost of handbuilt wheels can be considerable, but another way of looking at them is they're not really optional if you ride enough and are heavy. Otherwise one is liable to spend several times their cost getting the stock one fixed, as you've experienced.

Swapping the cassette on to a new wheel in and of itself and adjusting the rear derailleur if needed is easy and will work as well as it did before, more or less regardless of drivetrain wear. If you need a new drivetrain and feel it may not all be worth it, that's a separate consideration. It is true that new rear wheel time can be the moment where a bike is deemed not worth fixing.

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Your rear wheel needs to be replaced or completely rebuilt with all spokes being replaced. To a first approximation, materials have a limited lifetime - the cyclic loading will eventually cause them to fail. See https://en.wikipedia.org/wiki/Fatigue_limit

While the steels used in most spokes in theory can last an infinite number of cycles if the load is always below a critical value, in practice spokes are subject to corrosion and damage. Damage and corrosion create stress risers, causing forces at that point to exceed the fatigue limit of the material. There's also transient loads which exceed the fatigue limit, assuming normal loads don't already exceed the limit, which they very well might. Then there are manufacturing defects and residual stresses from making the spoke (see https://www.sheldonbrown.com/brandt/stress-relieving.html). All of that means in real life spokes wear out and start breaking.

And the aluminum parts of your bicycle don't have a fatigue limit under which they'd last an infinite time - aluminum under cyclic loads will eventually fail.

What this means is bicycle wheels wind up being wear items - they wear out faster than the bike itself. Replacing wheels because they've started falling apart before you replace the entire bike is quite common, especially rear wheels. Rear wheels do wear out and start failing long before most front wheels.

Front wheels wear out, too. Especially front rim-brake wheels. The braking surface gets worn down and the rim gets too thin.

It's not hard to learn how to rebuild your wheels. There are lots of good tutorials online. First, though, DO NOT GET A CHEAP SPOKE KEY/WRENCH. Cheap spoke keys/wrenches can work for occasional minor wheel truing, but cheap wrenches with their poor tolerances will cause you to round off and ruin a lot of nipples if you start using it for actually building/rebuilding wheels. Cheap spoke wrenches also tend to have small areas for you to push on to turn them. Building a 32-spoke wheel with a cheap spoke wrench will cause lots of rounded-off nipples, probably forcing you to start over on a bunch of spokes a number of times. And when you do finally get done, your fingers will probably hurt.

I can remove all spokes, to see the true form of the rear wheel (which is probably badly bend)

If you loosen all the spokes, and the rim is badly bent, it's going to be almost impossible to get a true rear wheel with even spoke tensions. Remember those fatigue limits from above? There's a good chance a badly bent rim can't be made into a true wheel without having some spokes routinely experience loads well above their fatigue limit.

Unmentioned so far: a poorly built wheel with improper spoke tensions, or one with badly uneven spoke tensions from a bent rim, will likely have at least some spokes that go completely slack under normal loads when being ridden. Having spokes go slack under load is a real bad thing for how long a wheel will last - slack spokes often become loose fast, causing the wheel to go out of true and likely cause other spokes that have to take up the load for the slack spoke to exceed their fatigue limit and fail much sooner.

This also bothers me:

can ask them to replace the rear wheel. A lot more cost, as the cassette needs to be transferred, and this would open a can of worms

Replacing a cassette is a routine activity. It's often done by cyclists just to get a better set of gear ratios for particular rides, for example. If your bike store is making a big deal of transferring a cassette and charging you a lot of money for that, find a better bike store, because they're ripping you off.

And finally,

I am around 110 kg (240 pounds)

You probably should be riding extra-strong wheels, then. Off-the-shelf wheels might not be strong enough to last long for you. Higher spoke counts and heavier rims are really what you need.

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    The 'huge effort' of transferring the cassette was my own (obviously unqualified) assumption. I haven't yet talked to the store about it. Thanks for a lot of good info. – Aganju Mar 14 at 19:50
  • Replacing/transferring a cassette requires two tools (a chainwhip and lockring tool) and about 5 to 10 minutes. There are plenty of videos on-line and the skill level is quite basic. – Carel Mar 15 at 15:05
  • @Carel Make that an afternoon for a beginner. Just spending 2 minutes on each spoke is the first hour or so. 5-10 minutes is a ridiculous underestimation. A beginner will not have taken the sprockets off then. Oh. Maybe I misunderstood: You don't want to put the hub on a new wheel, just the cassette -- then it's not ridiculous but just underestimated ;-) And if the shop does it, it's correct. – Peter - Reinstate Monica Mar 15 at 23:13
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Adding a little info on specific assumptions made in the question

I can ask them to replace the rear wheel. A lot more cost, as the cassette needs to be transferred and this would open a can of worms, the cassette is over ten years old and maybe should be replaced too

As others have pointed out, removing and installing a cassette is routine and easy

and when doing this, the derailleur ... should be replaced

Not automatically. If it's working fine then you can keep it, but you should check the idler wheels for wear. Replacements are not particularly expensive.

... chain, and the front sprockets also should be replaced

If you've never replaced the chain in 10 years, yes, it probably is worn. Front sprockets might be OK. As they have more teeth wear is distributed. Front sprockets tend to last longer that cassette sprockets.

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