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I have a bike with a 7 speed cassette. My question is can I swap it to a cassette with more speeds (like 10). I will change the derailleur to a compatible one.

marked as duplicate by mattnz, Criggie, RoboKaren, ojs, David Richerby Feb 4 '18 at 11:41

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EDIT As ojs points out in the comments below, the freehub's width of 7-speed systems mismatches those of 8- to 10-speeds. This means the rear hub/wheel has to be changed as well, in addition to everything listed below. Clearly a cost of such change now would exceed the price of a half new bike.


It would require changing the complete drivetrain and the rear wheel.

However, the good news are that a freewheel coming with 7-speed Shimano cassettes is compatible with 10-speed systems, so you won't need changing the rear hub/wheel.

The reason why the complete drivetrain has to be changed is that the front chainrings may not be working well with a narrower 10-speed chain.

  • The rear cassette has to be changed for obvious reasons to have more cogs
  • The rear derailleur has to be changed because of a different cable pull, range and tolerances required by a 10-speed system.
  • The rear shifter has to be changed to have 10 indexed positions and matching cable pull
  • The shifter cables/housings might be preserved, but they are cheap and it is recommended to change cables periodically to have better shifting experience, so it is highly recommended to get new ones.
  • The chain is to be changed because 10-speed chains are narrower, and a 7-speed one will be too wide and will jump all over the cassette.
  • The front chainrings are spaced to match a wider 7-speed chain. There is little possibility it will work nice with a narrower chain.
  • The front derailleur matches the front chainring spacing.
  • The front shifter goes away together with the derailleur.

What you need for drivetrain parts is called "a new groupset" — a name that encompasses all the parts I've mentioned.

Converting the rear wheel to a new hub would require a complete wheel rebuild. Oftentimes it means that buying a new complete inexpensive rear wheel would be cheaper.

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    Nice comprehensive answer. In almost all cases it's more cost effective to just get a new or used bike with a higher speed drivetrain than swap a whole groupset out. A 7 speed bike is either inexpensive or old and you will likely run into many compatibility issues. – Argenti Apparatus Feb 3 '18 at 18:26
  • Yes, of course i will change the rear derailleour..I talked with a bike mechanic, he said that i will need to replace only the rear derailleor, and maybe the chain..However i will change the shifter itself, the derailleour and the cables.... Woops i forgot the cassette :) – Dimitar Feb 3 '18 at 18:26
  • @Dimitar If you feel like keeping the old front mech, be prepared that it might not be working a smoothly with a 10-speed chain as one can think. I've heard about rather acceptable experience with using wider chains with narrower rings. But the opposite combinations was barely rideable as the narrow chain will not sit tightly on wide front teeth. Remember that Shimano as vendor does not claim that such setups are supported at all. – Grigory Rechistov Feb 3 '18 at 18:31
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    8 to 10 speed cassettes are wider than 7-speed ones and do not fit on a hub intended for 7-speed cassette. Check for example sheldonbrown.com/cribsheet-spacing.html for reference. – ojs Feb 3 '18 at 23:41
  • @ojs Thank you. I was not sure whether the incompatibility starts from 7 or 8 speed systems. Will update my answer accordingly. – Grigory Rechistov Feb 4 '18 at 7:53

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