Spare Tiagra Cassette - can I choose any?

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ike2112
Posts: 21
Joined: 19 May 2020, 10:57pm

Spare Tiagra Cassette - can I choose any?

Postby ike2112 » 16 Sep 2020, 12:30am

Just bought a cheap used bike to chuck on the indoor trainer over winter. Someone had refurbed an old Specialized Allez and put new Tiagra groupset on it.

They've actually done a really good job of it though so I am considering using it for some outdoor purposes also. In order to make it easier to chuck it on and off my Wahoo trainer, I was thinking I'll get a 2nd cassette. But do I have to be careful about what ratio it is, or even what brand to use? I've no idea if its actually a Tiagra cassette on it (I couldn't see branding on it the way its obvious on a brake caliper or derailleur).
Wasn't sure if I could just go on eBay and buy a 12-28 or 11-32 or whatever I want as long as it's 10-speed, and that it'll just work?

gxaustin
Posts: 601
Joined: 23 Sep 2015, 12:07pm

Re: Spare Tiagra Cassette - can I choose any?

Postby gxaustin » 16 Sep 2020, 12:35am

All Shimano 10 speed cassettes will work, as will Shram 10 speed. Even MTB cassettes.

Eyebrox
Posts: 323
Joined: 5 Aug 2015, 8:56pm
Location: Ayrshire

Re: Spare Tiagra Cassette - can I choose any?

Postby Eyebrox » 16 Sep 2020, 12:39am

Buy Tiagra 4700 10speed to match the change ratios from the lever. The rear derailleur is likely to be GS (medium length) so should allow cogs up to 34 teeth (11-34 cassette). Brucey is the expert here on Tiagra 4700 and he'll advise you fully in the morning.

thelawnet
Posts: 2421
Joined: 27 Aug 2010, 12:56am

Re: Spare Tiagra Cassette - can I choose any?

Postby thelawnet » 16 Sep 2020, 1:34am

The change ratio refers only to the match between a shifter which pulls more cable to move a derailleur a given distance and one that moves one less.

The cassette is blissfully unaware.

So as noted , any 10 speed is fine.

But if it's a short cage rd it's designed for up to 28t, and the long cage 34t.

So a 11-36t on a short cage definitely won't work, for example.

Brucey
Posts: 40534
Joined: 4 Jan 2012, 6:25pm

Re: Spare Tiagra Cassette - can I choose any?

Postby Brucey » 16 Sep 2020, 7:58am

yep, any shimano/sram 10s cassette will be OK, provided It is within the capacity of the derailleur. [Whilst not every 10s hub will accept every 10s cassette, yours probably will.] You will probably need an extra spacer behind the cassette when you fit it to the wahoo trainer; the freehub body on the trainer is likely to be a slightly longer 11s one.

Since the exact lateral position of the sprockets affects the indexing adjustment, and often varies slightly from one hub to another, it is probably worth checking and adjusting (using shims) the sprockets on the trainer, so that they match the wheels. This way you don't have to adjust the indexing when you change from road wheels to home trainer.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

gregoryoftours
Posts: 1286
Joined: 22 May 2011, 7:14pm

Re: Spare Tiagra Cassette - can I choose any?

Postby gregoryoftours » 16 Sep 2020, 10:09pm

Am I correct in thinking that you want to run one cassette when on the trainer and another on road? If you use 2 quite different cassette ratios you might have to run a sloppy chain on one to accommodate the one with bigger large sprockets on the other. Also b-tension screw setting on the derailleur might have to favour working better on one of the cassettes than the other.

ike2112
Posts: 21
Joined: 19 May 2020, 10:57pm

Re: Spare Tiagra Cassette - can I choose any?

Postby ike2112 » 17 Sep 2020, 11:51pm

Thanks all for the replies.

Emboldened by the first couple responses I went out and bought a 11-32 cassette (CS-HG500-10) which the bike shop fella assured me would work just fine, that anything bigger than that and I might have derailleur issues.
Though he also recommended I would need a new chain also. I didn't take him up on that as I wasn't sure, and he'd also already given me some sketchy info on bike lights I knew to not be 100% correct so just left with the cassette.

Tried it on the trainer with a spacer as per the Wahoo instructions (someone also noted above *), and it just wasn't right. Chain seems quite tight, no real smoothness in the mechanics at all, almost a slight grind and rattle at same time.

The cassette that was on the bike when I bought it was a 12-28. I put that cassette on the trainer and that was better, but not perfect (not anywhere near how smooth it feels on the actual bike/wheel riding outdoors, or even how its felt on trainers I've tried in stores.
That original cassette was pretty dirty, and hence the chain has become a little gritty just from these brief trials so I've just tonight deep-cleaned both cassettes in a pot of degreaser and cleaned the chain with a bath as thoroughly as I can without removing it, and the chainset and jockey wheels also.

So will try again tomorrow with it all super-clean, but I'm already thinking that I may need a new chain if I want to run 50/34 to 11-32 as opposed to 12-28? I didn't think 4 teeth would make that much difference and had expected the derailleur could adjust for that difference.
Are there even different sizes of chain links that could be causing the issue?


@GregoryofTours - yes ideally I'd like to basically be able to take the bike off the trainer and onto the road without having to faff with cassette removal every time. I'd like to just remove the QR skewer, carry it out the door, stick the wheel in and ride off.
But before I even get that far my preference is to get this new cassette working for this bike on the trainer. Being able to keep the old one on the wheel for quick changover would be a bonus.


* digression - - interestingly I previously had an old bike with 9spd Ultegra on the Wahoo and it only needed 1 spacer too; you'd think that if the Wahoo is designed for 11spd that you'd need 1 spacer for a 10spd cassette and 2 spacers for a 9spd, and so on...

Brucey
Posts: 40534
Joined: 4 Jan 2012, 6:25pm

Re: Spare Tiagra Cassette - can I choose any?

Postby Brucey » 18 Sep 2020, 10:04am

IME worn chains will run (roughly, but normally without slipping) on new sprockets, merrily ruining them as several times the normal rate in the process. And the larger sprockets will demand a longer chain too. So yes you should definitely use a new chain (of the correct length) with new sprockets.

However what you might find is that your new chain will slip under load when you use it with your old cassette, depending on how worn your old chain/cassette is.

You can use a different chain with each set of sprockets (swapping them is easy enough with a quicklink fitted, and it is a good excuse for cleaning the 'outdoor' chain too), but IME if either chain is worn past ~0.5% then it will be (increasingly) knocking hell out of your (expensive) chainrings.

BTW 8/9/(most)10s shimano cassettes all fit to the same freehub body (without spacers) so you usually need the same spacer to run any of these cassettes on an 11s freehub body. Up to a point more sprockets are accommodated by changing the spacing.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

ike2112
Posts: 21
Joined: 19 May 2020, 10:57pm

Re: Spare Tiagra Cassette - can I choose any?

Postby ike2112 » 18 Sep 2020, 4:21pm

Thanks Brucey

1 more question before I crack on with the next step. Dropped into another shop today for a chain, got a KMC as it has a quick-link.

But the fella told me I should measure the new chain against the old, then break up the links to fit the same. But surely - aside from having a nice unstretched new chain - the benefit/reason of this new chain is that I should keep it a bit longer since my top of the cassette will be 32 instead of 28? Should I not leave an extra link or two in, over the old one?

Brucey
Posts: 40534
Joined: 4 Jan 2012, 6:25pm

Re: Spare Tiagra Cassette - can I choose any?

Postby Brucey » 18 Sep 2020, 5:13pm

you should indeed only cut the new chain to fit the new cassette. Rule of thumb; enough chain for big-big, plus a couple of links for the derailleur. You can always make the chain shorter if it is too long, but lengthening it is always more faff, extra quicklinks etc.

Image

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

gregoryoftours
Posts: 1286
Joined: 22 May 2011, 7:14pm

Re: Spare Tiagra Cassette - can I choose any?

Postby gregoryoftours » 18 Sep 2020, 9:43pm

Look up b-tension adjustment too- if your chain is the right length but it feels rumbly on the biggest sprocket you may need to screw it in so there is a bit of clearance between the largest sprocket and the guide pulley of the derailleur.

rogerzilla
Posts: 1415
Joined: 9 Jun 2008, 8:06pm

Re: Spare Tiagra Cassette - can I choose any?

Postby rogerzilla » 19 Sep 2020, 12:04pm

I fitted an 11-23 Ultegra cassette in place of the 11-28 Tiagra one and much prefer it. The 11-28 was a bit gappy in the mid range. Looks a lot better, too.

Brucey
Posts: 40534
Joined: 4 Jan 2012, 6:25pm

Re: Spare Tiagra Cassette - can I choose any?

Postby Brucey » 19 Sep 2020, 2:07pm

rogerzilla wrote:I fitted an 11-23 Ultegra cassette in place of the 11-28 Tiagra one and much prefer it. The 11-28 was a bit gappy in the mid range...


- 11-23T - 11 / 12 / 13 / 14 / 15 / 16 / 17 / 19 / 21 / 23

- 11-28T - 11 / 12 / 13 / 14 / 15 / 17 / 19 / 21 / 24 / 28

with the 11-23 you get a 16T and 23T sprocket in place of a 24T and a 28T.

The only difference in the midrange is the 16T sprocket.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

rogerzilla
Posts: 1415
Joined: 9 Jun 2008, 8:06pm

Re: Spare Tiagra Cassette - can I choose any?

Postby rogerzilla » 19 Sep 2020, 3:54pm

39 x 16 is a very useful gear!