How To Fit Lower Gears | Cycling Weekly

How To Fit Lower Gears | Cycling Weekly

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How To Fit Lower Gears | Cycling Weekly

When faced with big riding in the hills, there are a couple of ways to make life easier.

You could change the chainrings, but with with a lot of bikes being specced with compact chainsets there isn’t very much wiggle room.

Instead, fitting a new cassette with lower ratios is the most effective way to go. It’s a bit of a job, but it isn’t too difficult, and actually just pairs together a lot of the things we’ve gone over in the past.

Things you’ll need:

GS rear derailleur (longer cage)
New Cassette with higher gears
New chain
HG Lockring tool and Chain whip
Masterlink pliers
Chain tool
Cable cutters
Phillips No.2 screw driver
Allen keys
Paper towel or rags.
The first job is to shift down to the smallest sprocket on the back and remove the crimp for the rear derailleur cable, then undo the clamp. Once done, remove the rear wheel.

If you’re only going up to a 28t cassette then you’ll be fine with the rear derailleur that you have specced. However, if you’re adding a 32t body to the rear then you’ll need to swap in out of a longer cage derailleur – GS in Shimano’s case, or the equivalent for other brands.

Now it’s time to remove the chain. If it has a quick link you’ll need to use your masterlink pliers to get it off. Alternatively, just use a chain tool to break it. Once you’ve got rid of that, use an allen key to take the rear derailleur off.

The next step is to remove the cassette. For this, you’ll need to place the chain whip on the cassette (so that is stops it rotating) and then use the lockring tool to undo the lockring. The cassette should then slide off the free hub body.

If in the rare occasion it is stronger than the freehub body metal it might bite into it but a couple of nocks should bring it free.

Fitting the new, larger cassette is simply a case of lining up the splines and slotting it onto the freehub body. Tighten with the lockring tool to 14nm.

After re-fitting the wheel it’s time to measure the new chain’s length. Fit the new chain over the largest sprocket and the largest chainring. Check the length (so it is as tight as it can be) and then add two links to it. Using your chain tool remove the links that you don’t need.

Now it is time to fit your new derailleur if you’re going to use one. Then fit the new chain, right way round and in the correct direction. You can join it using your preferred method, whether that’s joining pin of quick link.

It’s now time to setup you’re rear derailleur so you can get the gear shifting dialled in correctly.

Once complete, your bike should now be setup ready to head for the hills!


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  1. Anthony HT on August 6, 2022 at 11:27 pm

    OMG a Sram chain on a Shimano drivetrain, you must have lost your warranty! In essence, all you need to know is that for some setup, you might need some adjustment on the derailleur, cassette and chain. For me a 1×10 is enough. 50t chainring and a 11-28 cassette, and I can clear all the climbs in my area without having to deal with the front shifting.

  2. 1971hammydemuck on August 6, 2022 at 11:27 pm

    just fitted a 32 with a short cage. Just needed to adjust the B tension screw.

  3. CnE on August 6, 2022 at 11:33 pm

    Big Al’s the man.

  4. John Bouttell on August 6, 2022 at 11:36 pm

    Very helpful demonstration. Thank you.

  5. DFTA (Don't Feed The Animals) on August 6, 2022 at 11:36 pm

    out of curiosity, do you try to match the derailleur model number to the shifters or is it any GS that fits the amount of gears needed. for example if its an ultegra 6700 vs 6800. I’m sure it doesn’t matter, but looking for weighing in from the purists as well. 🙂

  6. sky Maracle on August 6, 2022 at 11:38 pm

    Pretty sure your chain is "one link" too long (by your reasoning)… 😉 double check shimano’s definition of a link.

    package says 114 links/116 etc…. pin to pin distance is half an inch… they don’t give you 9+ feet of chain in a package.

  7. TypeVertigo on August 6, 2022 at 11:41 pm

    The real reason why you want to lengthen your RD cage is to add chain capacity = (Teeth of largest cog – teeth of smallest cog) + (teeth of largest chainring + teeth of smallest chainring)

    The medium cage RD is recommended so it can accommodate as much chain slack as the system requires. With gearing like this, you don’t want too short of a chain – in my experience chain retention suffers at extreme combinations you might just happen to shift into without thinking about it.

    I would even venture to say that it’d be best to opt for the longer-cage or higher-capacity model of a rear derailleur, given the choice, to maximize versatility. There’s no real effect on shift speed or quality – evidenced by how Shimano made its latest Dura-Ace R9100 RDs with a single cage length that can accommodate a 30T biggest cog right out of the box. Compare that RD to other "short cage" models and its cage is actually quite long.

  8. tsuthebasa on August 6, 2022 at 11:42 pm

    you can use a 32 tooth casette with pretty Much every SS derailleur. I did it with sora, ultegra, 105 anda di2 ultegra SS rear derailleurs. check your b tension screw. if there is more place toplam go in than your good toplam go…

  9. Luka Cordedda on August 6, 2022 at 11:49 pm

    Short cage works fine with a 32

  10. Alejandro Martell on August 6, 2022 at 11:55 pm

    The idea and the information is good. I am grateful for it but I disagree with the idea that you follow the comercial tendency of putting 32 or 34 teeth as the lowest gear. I complain because the most important brands do it even worst, installing 11-28 as the standard one. You could have explained this same information with an example of a 11-42 Rocket, even if it was a mountain bike one. There should have to be added a few pieces, as a rocket spacer and an extensor for the rear derailleur, that if you don´t want to spend money in a mountain bike derailleur.
    The people who just want to climb the steepest hills, people not in a very good shape or fully loaded travellers would had be thankful,

  11. Prastt on August 6, 2022 at 11:59 pm

    how people still use oil for the chain so messy. i changed to squirt and never went back

  12. Matt Swain on August 7, 2022 at 12:00 am

    Great vid. I recently switched out my 28 to a 32 casette (and the GS rear mech)- or got my LBS mechanic to do so. However, I have been getting problems with the 32. Once shifted into that spot, the chain keeps spluttering like it wants to change. What’s frustrating is that I’ve taken it back to him twice, he sorts it, and then after a short time it does it again. I’ve recently fiddled with the barrel adjuster which has sorted it again, but I can already hear some slight splutter after getting back today. I wish I knew what was up with it. It’s all 105/Ultegra gear, and it’s so annoying – and a little disconcerting when riding – to have that go on. Any ideas?

  13. J B on August 7, 2022 at 12:05 am

    More complex than it needs to be

    I did not hear whether this advice was for 10 speed or 11, so assume he is saying it applies to both

    For 10 speed, just try the 32, it may work with the existing RD. if not, you do not have to settle for a 28, as shimano make a very nice 30 in Ultegra that can be found at a reasonable price. That should definitely work with the RD

    Should be similar for 11 speed, but I am avoiding it for as long as possible. Reason being that shimano MTB RDs work fine (from the 9 speed groupset) with 10 speed shimano road shifters – and a 36 cassette is no problem, probably higher

  14. Made In Canada on August 7, 2022 at 12:08 am

    Awesome video I wanna be a bike mechanic !!

  15. Christ On A Mtb on August 7, 2022 at 12:15 am

    Hellooo Al

  16. Francesco Nardone on August 7, 2022 at 12:16 am

    Sub compact chainsets are available from FSA and others. Don’t know about price but installation should be much simpler than changing cassette + der (if the BB matches).

  17. Normand Robert on August 7, 2022 at 12:17 am

    It is easy to misalign the splines on the last sprocket so some care is required to avoid that. Thank you for the "official" chain length tip.