New Cassette

[l4dva]

http://www.chainreactioncycles.com/Models.aspx?ModelID=443

http://www.chainreactioncycles.com/Models.aspx?ModelID=387

Hi there,

I have a spesh tricross sport.... I believe the rear gear mechs on these are mtb gear mechs? I am a bit unsure about which cassett i would need for it. The bike specs say it is a shimano HG50. Both the above links are HG50s but one is for MTB's (the decore) and the other for road (Tiagra). My shifters and front gears are all tiagra so im bit unsure?

Which one do I need for my bike?

Also which chain would I need as well?

Thanks in advance!

 

[fossyant]

Same animal........ get the one that suits your riding and sprocket range..... i.e. teeth - the MTB/Deore will have like a 12 - 32 but Tiagra maybe 12-27......

See what's on your bike now, oh and make sure it's the same number of sprockets...i.e. 8, 9 or 10....

 

[l4dva]

So there both the same thing? even though one comes under the mtb catergory and the other road?

acording to the bike specs i have 12 - 32. I guess ill just stick with that - decore it is then!

Thanks

 

[andyhunter]

when buying a new cassette always make sure new chain to as you will snap the old chain or else it wont work properly for smooth shifting or changing gears as old chain will have streched and worse and little and would not suit new cassette. go for xt and a kmc chain, thats wot i have on the mtb. as it will last far longer.

 

[l4dva]

Thanks andy, i was looking to replace both....any idea which ill need for a 12-32 9speed cassette? Its a triple aswel?
Thanks

 

[I am Spartacus]

You dont have to stick with the larger range cassette which is more MTB focussed.. the Shimano hub will accept any Shimano cassette which has closer ratios 11 - 23 or 12 -21 Tiagra.. or Ultegra 9 speed of course to match shifters.
If you are using a triple, assess your riding and gear selection pattern and make a choice for yourself.
Any good qual 9 speed chain ... personally I avoid the Shimano brand as the side plates seem made of cheddar and break easily..

 

[l4dva]

Spartacus - I did actually think of changing the ratios.... at the moment i prety much never use the 'granny' ring and on the rear cassette im mostly in the higher range of the gears that i have. When I first started cycling i pretty much always used the lower end but my legs have powered up since then.

I guess if I change the ratio to something lower I will need to adjust my rear gear mech?

I want to stop using the LBS as they charge silly amounts, looking at the chains/cassettes etc on line they are so much cheaper and with the labour cost savings as well would save me loads of money.

I've seen the videos of how to change cassettes/chains and this looks like a straight forward job that I could easily do myself (im going to get the correct tools as well, its got to be a worhtwhile investment) but the gear adjustments look a little more tricker I want to master this as well eventually as well but i guess might take a bit of time to sus that out

 

[andy_wrx]

The Tricross is a sort of everything bike - cyclocross, commuter, tourer, roadbike.

If you do want to ride in muddy cyclocross races or hilly technical offroad, then you'll want lower gears.
But if you ride it onroad, or offroad but on smooth gravel tracks, then you might want to get road gears instead

If you currently have a 11-32 cassette on the rear and 52/39/30 triple, then onroad they would get you up the North Face of the Eiger, so if you're saying you hardly use the smaller 30 ring at the front nor the bigger cogs at the rear, I'm not surprised.
- a roadbike triple would more commonly have a 12-25 cassette at the back

If right now you sometimes feel that you want to be in an 'in-between' gear, where you're currently in too low a gear but if you change-up it'll be too high, then with 9 gears spread across 12-25 rather than 11-32, they'll obviously be closer together with smaller gaps in the ratios between them.

If you have a LX rear derailleur, yes this is a MTB rear mech, but it'll happily handle 12-25 (after all, it can manage 11-32 and 12-25 is just the middle bit of that !)

If your chain isn't worn, you could simply just fit the new cassette.
You'll need a chain whip and cassette lockring tool (plus spanner or socket set to hold lockring tool), that's all.

But if your chain is worn (and your old cassette is worn to match it), then running a new cassette with your old chain will make it jump, which is irritating at the least.
I'd buy a KMC or SRAM 9sp chain (X9 or 951 would be fine) because these use a 'missing link' type connector which is sooo much easier to use than the joining pin on a Shimano chain (and if you mess up fitting a Shimano pin the chain could split apart again, which could be dangerous).
A new chain will be too long, you take the excess links off and cut it to size, so you need a chain tool to do this.
If you have gone from 11-32 to 12-25, the chain needs to be a bit shorter than the old one you took off (which had to cope with you potentially running 50front vs 31rear, now only 52 vs 25), so take off a couple more links.

Just fitting a new cassette and new chain shouldn't cause you to have to adjust your gears.

Have a look at Park Tools and Sheldon Brown websites for more info/help.

 

[l4dva]

Thanks Andy thats some real good advice! I might just go for the 12-25 ratio in that case, sounds like that will suit my needs better!

Both my cassette and chain will need replacing soon so ill deff change them both together.

Sorry another daft question for you.... am i right in assuming the front chainrings will out last a number of chains/cassettes before they need replacing? Or do the chainrings wear down at the same rate as the chain/cassettes?

 

[GrasB]

If you have a LX rear derailleur, yes this is a MTB rear mech, but it'll happily handle 12-25 (after all, it can manage 11-32 and 12-25 is just the middle bit of that !)

Not strictly true, the parallelogram of the rear derailleur will be optimised for a certain range. If you go to small on the largest gear then there's to much chain between the cassette & the pulley for crisp changes.

 

[l4dva]

GrasB - ok, so any ideas if a 11-25 will be out of that optimum range using the LX derailleur?

 

[andy_wrx]

Sorry another daft question for you.... am i right in assuming the front chainrings will out last a number of chains/cassettes before they need replacing? Or do the chainrings wear down at the same rate as the chain/cassettes?

You're right in thinking they'll outlast the chain and cassette

Because they're bigger, chainrings tend to wear considerably less than cassettes
- more teeth to spread the wear across
- more teeth holding the chain at the same time (think how many teeth in the chain when it's on the 12 cog and how many in it when on the 52 ring)


We're saying replace the chain, but that's because you're replacing the cassette.
If the chain is not worn, actually you don't need a new chain, but if you've had the bike for a while/a few miles, for the sake of £15 or so, I'd replace the chain.

More common is to be replacing a worn chain, and have to replace the cassette too.
If you use a chain-checker, or measure the chain with a steel ruler, and replace it before it gets too worn, then you can simply replace the chain and can continue with the same cassette, so it's not automatic that you have to replace both chain and cassette.
You only need to replace the two as a pair when they have both worn together as a pair, as a new chain/worn cassette or v.v. will 'skip'.

(and it's a personal decision - some people weigh-up the cost of replacing chains more regularly against the cost of replacing chain and cassette, decide that they'll let the chain and cassette get worn and have to replace the two.
I had an old clunker 10speed bike from the 1970's with a really worn chain. If I replaced it, I'd have had to replace the freewheel (older version of a cassette) and also the chainrings, because all were really worn. The cost of this lot was more than the bike was worth so I just kept riding it)

 

[andy_wrx]

Not strictly true, the parallelogram of the rear derailleur will be optimised for a certain range. If you go to small on the largest gear then there's to much chain between the cassette & the pulley for crisp changes.

Well agreed, but your words are 'optimised' and 'crisp changes'

11-32 (or potentially 11-34 as you can get MTB cassettes that big that a LX rear mech would have to cope with) is a big wide range, so it will be a compromise.

But if the LX rear mech can handle that whole range, it can certainly handle 12-25, it just won't be quite as crisp as a road triple rear mech which is designed only to handle upto 12-27.

It will have a really long arm so as to get out of the way of the cassette when on the 34, longer than it needs to be when on a 25, so it will need a slightly longer chain than a road triple.

If you wanted the optimum rear mech, you'd replace with something like the Tiagra GS http://www.chainreactioncycles.com/Models.aspx?ModelID=19461 but that's another £25 to spend : optimum but not necessary

 

[GrasB]

Well agreed, but your words are 'optimised' and 'crisp changes'

11-32 (or potentially 11-34 as you can get MTB cassettes that big that a LX rear mech would have to cope with) is a big wide range, so it will be a compromise.

But if the LX rear mech can handle that whole range, it can certainly handle 12-25, it just won't be quite as crisp as a road triple rear mech which is designed only to handle upto 12-27.

Well with experience of an older XT rear mech I'd call a 3~5s of clicking until the gear changed between the last 3 gears of a 12-21 road cassette is well beyond being a little lose & is rather unacceptable.