Hi all
I have a triple chainset on my road bike and want to convert to a compact double.
The rear cassette is 9spd and the Tiagra sti shifters are for a triple up front (naturally!) and 9spd at the rear.
Couple of questions:
1. Would it be possible to swap the front chainset?
2. What would be the highest ratio for a road cassette? i.e 11 – 30? or could i fit a MTB cassette? (its very hilly where i live)
3. Would my front changer be ok with a double?
I want to change because the triple is pig ugly & very heavy
Cheers all

When you say you want a compact double, do you mean a compact or a double? Both have two chain rings, a compact is 34/50 gearing, a double is usually 39/53.

11-28 is the highest road cassette (I think campag might do a 12-29 though), but yes, you can fit a mtb cassette, so you could put a 36 on if you really wanted (I think).

I’d need to do some checking.

The big one is are Shimano STIs 2/3 ring compatable, I don’t think they are? I think they’re 2 or 3 specific. And Campag doe’s both. May have that the wrong way round.

Same with the front mech.

And I think you’re max with a Tiagra road mech is 28.

Top of my head this is.

Bottom bracket might need to be changed for a shorter one.

He’d need an MTB mech to go any higher, but the STIs will shift that mech.

To go larger than 28 at the rear you will need a MTB rear mech. You will likely need a new front mech and shifters too. Seems to me that you have been sucked into the anti-triple fashionista.

Shimano appears to be either 2 or 3 speed specific.

Tripple might shift twin, I don’t know.

Do you live near Croydon, Marco? ❓

you can get the tripple shifters (and triple mech) to shift a double, but it’s not good as you don’t get the “trim” position that you would get on double shifters (i.e. the inbetweenie position that allows you to use the big ring and larger rear cogs without chain rubbing on the inside of the front mech) – so it’s not ideal.

have a look at SRAM Apex for wide ration road gear setup…

better off hunting down a light weight triple chainset imo. Truvativ make some great value good looking and light weight triple road chainsets. I upgraded mine that way and shed a load of weight from my original Tiagra triple setup.

you can get a triple shifter to work with the double just use the limit screws of the mech to stop over shifting.

I would replace it all. I have a triple Tiagra but I am rarely in the granny except when going up the likes of the Lecht, Cairn o’mount and the Suie so I’ll be replacing it with the new tiagra compact when it hits the shops in August aparently. I might get a couple of different cassettes depending on the ride.
The weight is not a problem, I just want a more functional set up.

Hi
Thanks for all the very helpul replies
RealMan: Yeah i meant a compact 34/50
Elfinsafety: No live in West Yorks, sorry
Druidh: No not really, although i do prefer the look of a double chainset, its more for practicality, i dont use the granny on the triple very much
Cheers all

I want to change because the triple is pig ugly & very heavy

LOL.

take the wee ring off, save 30gm and about £100 🙄

Bear in mind that with a compact you get a big change in speed when you shift between the two rings resulting a having to change several sprockets at the back. Some people are fine with that, personally I hated it.

marco – Member
Druidh: No not really, although i do prefer the look of a double chainset, its more for practicality, i dont use the granny on the triple very much

Great – you’ll not need greater than a 28T cassette then