Changing cassette for climbing

[ChristinaJL]

Earlier this week, I did my first 30 mile route round Snowdonia. It included going up Llanberis Pass in the rain, what fun!! However, not having done hardly any climbing before, I did find I was straight onto the lowest gear pretty quickly and could have done with a few more gears.

So, my question is, can I change the rear cassette on my bike to give me more granny gears for climbing? I have a specialized dolce elite 2008 womens' road bike which is currently running a SRAM PG-950 9 speed with a 11-28 tooth range. Could I change this to the same model cassette but the 11-34 tooth one and if so, would this give me more gears so I can spin up on? Am I right in thinking that if I pick the 9 speed one, but with different ratios, I won't have to change anything else on my bike? Or would I need to change the rear deraillerur, I currently have a shimano 105 long cage one on. The chainring is a shimano tiagra 50/39/30 and I have Shimao Tiagra 9 speed STI levers.

Excuse the dim question and not phrasing it that well, but I'm not very technical!!

 

[Amanda P]

The only dim question is the one you don't ask. It's a good question and put very clearly.

I would be very surprised if your current setup with a long cage 105 couldn't handle a 34 tooth sprocket. The only problem you might have is if your chain isn't quite long enough - but that would only become an issue if you tried to use the biggest sprocket and biggest chainring at the same time - but that would be silly.

 

[HLaB]

I'm not an expert on this you might need to put a larger derailleur on, it depends upon what's already there and you will most certainly need a new chain. the new chain may also need an extra pair of links; I used this guide the last time I changed cassette size (but I went down from a 11-34 to a 11-30) to get the new chain length.

PS the other vids on the Bicycle Tutor site are good too

 

[4F]

The only dim question is the one you don't ask. It's a good question and put very clearly.

I would be very surprised if your current setup with a long cage 105 couldn't handle a 34 tooth sprocket. The only problem you might have is if your chain isn't quite long enough - but that would only become an issue if you tried to use the biggest sprocket and biggest chainring at the same time - but that would be silly.

Agreed

 

[Tynan]

if you got up a major hill with the gears you have and aren't anticipating bigger hills, you'll quickly get stronger

 

[ChristinaJL]

Thanks everyone, I think I'll go ahead and order the new cassette and see how I go, I can always take it off!! And time for more practise, so I'll have to find longer hills in Shropshire now to cycle (or crawl ) up!!

 

[andrew_s]

To use a 34T cassette, you will need an MTB rear mech.


It's not the cage length that matters so much as the parallelogram angle and how far from the axle the top jockey wheel is when in bottom gear. Road mechs are generally designed so that it's as far out as a 30t cassette extends. If you tried to shift onto a 34T sprocket with a long cage 105 mech, the jockey wheel would hit the side of the sprocket rather than lifting the chain onto it.

 

[ChristinaJL]

To use a 34T cassette, you will need an MTB rear mech.

Ah, I see, thanks!! Which one would you recommend to go with my set up?

 

[TheDoctor]

Loath though I am to disagree with Uncle Phil, I'm not sure that a 105 rear mech will cope with a 34T cassette. Try it by all means, but be aware that you might need to get an MTB rear mech. They're not too pricey - from about £15 depending on quality.
Another option for lower gears (assuming you have a triple) is to simply swap the 30T inner ring for a 28 or 26. Inner rings are dirt cheap, and it'll even make the bike (a tiny bit) lighter!!

 

[ChristinaJL]

Another option for lower gears (assuming you have a triple) is to simply swap the 30T inner ring for a 28 or 26. Inner rings are dirt cheap, and it'll even make the bike (a tiny bit) lighter!!

I had thought about swapping the inner front chainring to a size like the 26, but wasn't sure what would fit with the tiagra chainset I have, as a quick look on the internet and I was confused. Eg. at CRC they only had the 3 sizes I already have as a tiagra chainring, so I'm assuming I'll have to pick another sort? Now my poor head hurts!!!

 

[andrew_s]

The only thing to watch out for with MTB mechs is that some are "Low Normal" or Rapid Rise. This means they are spring loaded towards the large sprockets and the cable pulls the mech towards the small sprockets. They work, but you would have to get used to using your STI levers the wrong way round (i.e brake lever to shift up, small lever to shift down a gear). You want Top Normal.
I'd suggest LX http://www.chainreactioncycles.com/Models.aspx?ModelID=32898 or Deore http://www.chainreactioncycles.com/Models.aspx?ModelID=40543

You will need 74mm bcd chainrings to replace your 30T chainring.
Steel £7, cheap alloy £9, good alloy £13, posh ally £20
I use steel for my small ring as there isn't much weight penalty, and small alloy chainrings wear quite quickly

 

[Bayerd]

If I were you I'd stick with what I've got. Use your inner determination to say to yourself that you'll get up the hill 'no matter what'. Do this on a fairly regular basis and you'll soon wonder what the fuss was about.

If you change cassette, you may find it easier initially, then as you get stronger you'll want to go back to the cassette that's currently on the bike and realise you didn't really need the extra one......

 

[HJ]

You could swop your current 30t granny ring for this 28t one, although it says for MTB it will fit your tiagra crank set without having to change the rest of your set up.

 

[battered]

Swapping the granny ring at the front as stated above would be my choice. Costs next to nowt, easy fit and easily reversible if you gain thighs like Tessa Sanderson and go screaming up the Pass at 20mph glued to Bradley W's rear wheel. :-)

 

[TheDoctor]

If you're cycling around Llanberis regularly, you could hook up with Plax of this parish.
Going cycling with her will improve your climbing no end, or destroy your will to live.
I'm in the second camp. She's much better at climbing than I.