kwf

Hi all,

I'm looking at purchasing a beautiful Merlin Extralight someone's selling near me. It's perfect, except that it's kitted out with a triple crankset (Shimano Ultegra triple), which I doubt I will want or need, as I am currently riding a triple (on a heavier bike!) and have used the smallest chainring exactly never, even on steep hills.

I'm considering replacing it with a similar quality double, and I want to make sure I'm accurately evaluating the price of the operation. Presumably I'll need to also replace the front derailleur and one of the shift levers (Shimano 105), but I'm not sure if I'm forgetting any other parts besides the crank/chainrings, derailleur, and shift/brake lever, that I'll need to swap out. Any hidden gotchas in doing something like this that I should be aware of?

Thanks for your help!

upthywazzoo 

Assuming you're not using an old square taper bottom bracket, then no, your bases seem to be covered.

fietsbob

Screw in External bearing assemblies replace the cups of square taper BB .. & visa Versa.

Frame threading of British standard is adaptable ..

You have tastes for premium stuff whats your hesitation at throwing More more $ at it ?

goenrdoug

the bottom bracket will be wider for the triple. You'd want to replace that.

rmfnla

Technically you don't have to swap out the either FD or the shifter; you can just re-set for two shift points and be done with it...

kwf

What are the downsides to doing something like this? Do you know where I might get more info about whether the Shimano 105 triple shifters can be converted like this (some googling around has failed to turn up results).

rmfnla

No downside and no shifter conversion involved.

I know because I did it on my own bike.

I set my Curtlo up as a flat bar and went with MTB shifters and FD with a Dura Ace 7703 triple crank.

After about six months I realized I had not used the granny even once so I took it off. The D-A 7703 crank uses an unusual system; the small chainring mounts to the middle ring, so all you have to do is detach the little one and you have a double! I did swap out the 118.5 BB for a 109 but that was it.

You can remove the inner ring on your crank and use it as a double if you want but unlike my D-A you will still have the bolt bosses on the inside of the spyder. Your call.

Once you have the crank the way you want it just use the FD limit screws to match the two chainrings. The shifter should be adjusted so the granny shift position indexes on the middle ring and the middle shift position indexes on the big ring. The FD limit screws stop the shifter from accessing the third position.

Good luck...

Drew Eckhardt 

Try a cassette with one tooth jumps to the 19 cog before you get rid of the triple. 13-21 8-speeds, 13-23 or 12-21 9, 13-25 or 12-23 10 cogs.

Lots of people find that nicer than a double with the same range because there's no big jump on flat ground or increased front shifting.

Drew Eckhardt 

The Q factor will be slightly higher than if you got a double crankset which may in turn require a double front derailleur due to the chain line difference (I could never get a Campagnolo triple derailleur to run right on a double crank, although the correct double derailleur was perfect on the first try).

If your cleats aren't already at the outside of your shoes you may be able to adjust around that for no effect.