After I have replaced chain and cassette, should I expect the replaced parts to last more, less or about the same?

The rationale behind putting the weaker component in the factory may be that many bicycles are not used much, so also more cheaply made part may last the life span of the bicycle or at least long enough to consider this as sufficient.

I am not sure if say all cassettes marked as SLX M7100 are identical or it may be some more specific variations under this number.


2 Answers 2


If the part number is the same, most likely it has the same quality.

What many bike manufacturers often do is to put a Deore XT rear derailleur, then every other part including cassette, chain, cranks, chainrings, pedals, front derailleur, shifters, cables, housings, hubs, brakes, brake levers, bottom bracket, etc will be the cheapest the bike manufacturer has found, whereas only the rear derailleur is Deore XT, and the bike is advertised as Deore XT bike.

But if the cassette the bike has, has a part number, and that part number says SLX M7100, then you can be reasonably sure it's as good as another SLX M7100 bought from the spares market.

  • 1
    FTR, combining an XT derailleur with cheaper parts is actually a pretty sensible thing for the customer. The derailleur is the single part with most influence on shifting quality, and if you want to make it even better then the chain and cassette are obvious points for upgrades after the originals have worn through. Commented Nov 2, 2022 at 23:13

I’d be very surprised if a bike parts manufacturer would do different quality assurance or even different production runs for different customers.

If you buy a fully assembled bike the company (or bike shop) which performs the assembly might do some basic quality checks and would probably replace parts which are obviously bad.

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