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Triple to Double?(11 posts)

Triple to Double?crestlinefarm
Jan 14, 2004 10:09 PM
I guess I could run out to the shop and look for myself... but it's cold and raining and it's 200 yards away!
Is it possible to change the chainrings on a triple crankset and replace it with two? Or even better, can I just take the tiny ring off and leave the other two?
I know I'm probably missing something...
re: Triple to Double?OffTheBack
Jan 15, 2004 3:48 AM
You can definitely remove the small ring and keep the other two. Just make sure to adjust the limit screw on your front derailleur so you dont throw the chain off to the inside. Depending on the crankset, the bolt circle for the outer two rings is probably the same as a double, so if you want to change from 42/52 to 39/53 it should be no problem.
re: Triple to Double?PEDDLEFOOT
Jan 15, 2004 5:59 AM
I just had it done to one of my bikes.I had the small ring of the triple removed. It works great.No problems as long as you set the limit screw properly.
But Why?bimini
Jan 15, 2004 7:18 AM
Other than a double being cool just removing the small ring will not improve shifting or make chain drops less likely.

The only real reason doubles may be superior is with two gears the chainline varies less than a triple, which reduces wear, improves efficiency and reduces the risk of chain drop ever so slightly. You can also go with a shorter arm on the rear deraileur which is said to improve shifting response slightly and may also help reduce chain drop.

On a triple the chain line is centered on the center gear. On a double it is between the two gears. To correct this on Campy you need to change out the BB and the possibly the crank set. (Don't know on Shimano). The effects of this are minor.

Dropping the small gear will not decrease the performance over yout current triple set up. You just will not get the slight performance increase that a better chainline will give by using a double crank and BB.

May as well leave the small gear on and use a 12-23 or 12-21 on the rear. Then you have your bail out gears for the hills and nice tight spacing so you are always running at your optimum cadence.

By the way, I like and run doubles but would never have been able to climb Haleiakala a few weeks ago without a triple.
Found a good deal on a carbon triple crankset....crestlinefarm
Jan 15, 2004 9:24 AM
But everything on the bike is setup for a double. Changing the bike to a triple would mean new shifter, bb, & front derailer so I wasn't even considering it. But if it's a matter of pulling the little ring off, then just maybe...
I thought you were changing a bike that was alreadybimini
Jan 15, 2004 9:59 AM
set up for triple to a double. If you are trying to use a triple crank on a double bike then simply removing the small gear should work. I'm not certain if you will need to use a different BB. I know you need to go with a longer shaft in the BB for a triple crank on some bikes because of interference and getting the front deraileur to land right on the small ring but these problems should go away when you remove the small ring. There may be a problem with the range of the front reraileur reaching to the large ring, but with a short 2 ring BB there is a good chance you have enough reach. Just set the stops for the new crank and chainrings.
Not Quiteasgelle
Jan 15, 2004 10:06 AM
I think you'll also need a new bottom bracket (or at least a new spindle) to handle the wider triple crank and a new triple front derailleur. I don't think a double has the range to reach the big ring on a triple crankset, which is further out than on a double.
Not worth itChen2
Jan 15, 2004 11:54 AM
Generally the middle ring on a triple is a 42 and most doubles these days have a 39 inner ring. If this carbon crank has a 42 in the middle you will probably need to change it to a 39. If you want a double stay with what you've got, or if you just have to have a carbon crank get a double.
Agree: Easy to do, but there's no real benefit.Cory
Jan 15, 2004 9:26 AM
I'm king of the triples, and I have them on all my bikes now except the singlespeed. Even allowing for that bias, though, I can't think of any reason to spend the time and money to swap to a double. Whatever you'd gain would be so slight that I doubt you'd ever feel it.
My bike was a double ....PEDDLEFOOT
Jan 15, 2004 1:27 PM
...and the crankset that I wanted came as a triple.I wanted a 46/36 crank.It came as a 46/36/26.Because it was only a double to begin with I wanted the same look.Thats why I had the small 26 ring removed.
For what it's worth....PEDDLEFOOT
Jan 15, 2004 1:29 PM
...my other bike is a triple and I will be getting the same crankset on that.I will be keeping the 26 ring on that one.