Geewhiz

Hello!

I currently have Shimano Tiagra with a triple crankset up front and 105 in back. I was wondering how difficult a process it would be to switch to a double crankset up front. Would this be as easy as just buying and installing a double crankset (i.e. are the tiagra shifter and derailleur compatible with a double as well as triple), or would I need to replace the front derailleur and shifter as well?

Thanks!

Bikewrench217

You might be able to make it work. It will require really playing with the limit screws on the current front derailure. Problem you will run into is that your current lever has 3 clicks and going to a double crank set up front you will only need 2 clicks. So you may experience major over shifting and chain dump mostly due to the inside.
So set your limit screw so the derailure doesn't move all the way in and run your shiift cable as tight as possible. Good Luck

Procione

Try that, and if it don't work, buy some used shifters, and sell the ones you have, CL - e-bay is good for that kind of stuff.

CACycling

You'll need a new FD. The triples and doubles are different.

lunchbox1972

If you wanted to sell the Tiagra triple and BB, I might be intersted..

Al1943

Tiagra shifters go both ways.
You'll need the double crankset and matching bottom bracket.
Your triple front derailleur will probably work OK with a double crankset, a double FD might be quicker to shift.
Not sure what you hope to gain.

Al

Geewhiz

Thanks to everyone for your input. I'm not sure if this is something that would be worth doing--but at least now I have a much better idea of what it entails.

jotaeh

I switched out the Ultegra triple on my Klein to an Ultegra Compact Double. Aside from the crankset, you'll need a left shifter, FD for a double, and also a short throw rear derailleur. Your triple likely has a long throw RD. The left shifter for a double will have one less click. I tried using the triple FD, but I could not set the stop screw far enough to prevent the chain from jumping off the inside of the small chainring on my setup. You could tension the shifter cable to prevent the chain from jumping, but it's a bit of a hassle. FDs aren't that expensive. Depending on your setup, you may need a new chain, but most likely you can reduce the number of links on your existing chain to get the correct length. Make sure you also match 9spd vs. 10spd. I also went to a 12-27 cassette and lost only a couple of gear-inches from my triple, and the compact is so much crisper to shift. Good luck if you decide to do it.

ls01

Geewhiz
why not just remove the small ring and use the limit screw to lock out that position. be a lot cheaper in the long run.
the tripple rear derailure will work reguardless of the front. but its up to you. The front shifter is the same double or tripple.Sora, tiagra and 105 are not specificand I believe 6500 (ultegra) isnt either but 6600 is double or triple specific. the front derailure will work with two rings. you just need to set it up properly.
If you want to make it like it was always a double, you will need a short cage rear derailure a new bottom bracket and crankset a new front derailure. shorten the chain . the front shifter is the same.

Al1943

lsO1 is correct.

Rogue Leader

Quick question of why you want to do this? That will help us give advice.

Firstly your Tiagra shifters (at least newer ones) will work with double or triple so you won't have to change them. Secondly depending on the crankset you get you may need to remove or replace the bottom bracket. If for some reason you go and buy a brand new Tiagra or 105 double, you need to remove your bottom bracket and replace it with bearing cups which are cheap. Otherwise your current bottom bracket may work with it depending if its square taper or octalink, what make and model crankset do you have now?

Don't jerk around with setting limit screws on the FD to try and get the triple front to work with it, you can get a brand new Tiagra double FD on ebay for $17. I see no reason to risk dumping the chain because of a missed shift to save 17 bucks.

Finally the RD, you MAY have a long cage RD. If you go with a standardish double crankset (like 53-39 or 52-42) it should work fine. If you go compact (50-34, which is what I suspect you may be looking to do) you will need a short cage rear derailleur. 105s can be had on ebay new for around $40.

operator

And wrong.

Sti triples will work with doubles no problems.

And wrong.

Please stop posting if you have no idea what you're talking about.

Al1943

Why?

Barrettscv 

+1

DMF 

This is either wrong, or needs explanation.

efetch

you will also need a different bottom bracket. there is a double length and a triple length. use the first and second positions with your shifters and by simply adjusting the derailleur properly you will not even be able to hit the third position on the shifter. you can keep the same rear derailleur but if you were planning to change that for no good reason your chain should be shortened also

Rogue Leader

I'm wrong. Was going with the recommendations from Campy for when I bought my groupset... however I did a little research and found that it doesn't matter.

I was also hoping th OP would respond with what size he was going with his crankset.

Metaluna

Problem with that is the remaining rings will be too far outboard to give you full use of the cassette without severe cross-chaining, especially the big ring. So I think you'd lose some gear ratios, unless you play with the chainline (not easy if it's a Hollowtech 2 crank).

Metaluna

I haven't tried it, but in case anyone's interested, this thread gives instructions on how to set up an STI triple lever to shift a double.

DOS

Listen to the posts in this thread that say the shifters will work and the derailleurs will work with a double crankset. If you go with double, you would have to change the BB to get the right chainline (I think with shimano cranks that usually means dropping from 118mm spindle to 113mm but check the specs for the cranks you end up getting)

jasonrobo02

As a few have mentioned, any derailleur (long, medium, short) will work with a double crankset. The general rule of thumb is to use as small of a derailleur as your gearing allows for the crispest shifting. The length of a derailleur cage allows for more/less chain slack to be accomodated. Shimano doubles are usually good for 29T while the medium cage (often referred to as long cage) can handle somewhere around 35T. The long cage (used on mountain bikes) can handle even more.

OP, last year I swapped out a 105 triple drivetrain because I wanted to use an FSA compact crank. The obvious requirements are the crankset, bottom bracket, and chain length. All other components are optional. I still run my triple front derailleur because it flat out works great! I left the 105 medium cage derailleur on and it was fine. I later upgraded to a short cage and it's even better.

Moral of the story: If money is tight, buy your crankset and bottom bracket and set your chain length. If you have more money, then you can upgrade the derailleurs.

Al1943

Shimano does not make a medium cage road derailleur. Their medium cage is a mountain type derailleur that, like their other mtn. derailleurs, can handle up to a 34t cog. The Shimano road derailleurs are either short or long and are all rated at a maximum cog size of 27t, but will handle at least a 28 and usually more.

Al1943

The setup instructions offered by MisterMike at RBR are good. They are basically the same as Shimano's instructions or the instructions found at https://parktool.com and are good for either a triple or a double.

jasonrobo02

Looking back at the Shimano nomenclature, you are definitely correct. I'm not sure where I got the short, medium, long stuff from.

Metaluna

Well the mountain derailleurs have GS and SGS variants which are often referred to as medium and long, while the road RDs are SS and GS, so its easy to see where someone would think of them as SS=short GS=medium SGS=long.