Component lifetimes

xxamr_corpxx said:

1) Is it possible to replace worn 105 derailer jockey wheels with other brands? I have some Suntour and SIS ones lying around.

Yes, you usually can replace the jockey wheels with non-genuine equivalents, so long as they have the same number of teeth and fit in the same way. (The only experience I have with replacement ones were some BBB brand jockey wheels that fit just fine into a Shimano derailleur)

Quoted post said:

2) How many kms will the chainring and cassette last me? (Assuming I change the chain before it elongates)

It all really depends on how dusty/wet/etc. it is in your area and what sort of a cleaning regimen you run.

If you replace the chain before it gets to 1/8" stretch, you can usually get a few chains' worth of life out of a cassette. One minor thing to remember is that your 'favourite' cogs on the cassette will wear out sooner than the ones you use less often.

Chainrings are generally the longest-lasting part of the drivetrain, as the force of the chain is distributed across more teeth.

Quoted post said:

3) Do the derailers have a lifespan? Do they ever need replacing?

Umm, not really.. I guess you could characterise a derailleur 'death' when there is too much play in the derailleur cage's pivots.

Just replace them when they stop working properly I guess 😉

105 is one of the best values in the Shimano line, often viewed as more durable than it's high end brethren. Nobody can tell you how long stuff lasts since it is so dependent on riding style. Tooling around the park versus racing is a big change. Things like chains, chain rings and cassettes are easy enough to measure for wear. As far as the derailers and brifters go, use them until they break.

If you look after the drivetrain, cleaning and lubing it regularly, it will give you no problems for some time. Modern 10 speed chains are a bit less long-lasting than the chains of the past, but I believe (could be wrong) that you can easily get 5 ~7,000 km out of a chain that is well maintained.

Brifters and derailleurs will last a long time.

Of course, if you consider Campagnolo, things are more rebuildable, but there really are few if any issues with a solid group like the 105.