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Old 02-04-12, 07:55 AM   #1
tubapro
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Triple to Compact shifter question

So I have a 2010 Trek 2.1 Triple road bike. My local bike shop persuaded me to switch my crankset out from a triple to a compact double (50/36ish - rear 12-27). I like the compact setup better and it seems less clunky shifting. The only problem is that they changed out the crankset only and re-used the triple shifters and derailleurs. On the 50 front chainring and the rear 27 and the gear below it, the chain barely rubs on the FD. Not a huge deal, but I'd prefer it not be there if possible. Is there enough adjustment with the triple shifters for a different mechanic to make this go away, or do I need to swap out the left shifter and the FD to a double setup? (or just the shifter and re-use the FD?) A different shop priced me $320 for a new shifter and FD plus labor. I'm thinking I could find one used and they'd install it for me. I'd like to go with a better rear cassette and chain later and it would seem silly to do it while it's going to rub a little.

Oh, These are Shimano 105 shifters/FD/RD. They have flight deck written on them.

Suggestions?

Last edited by tubapro; 02-04-12 at 08:02 AM. Reason: left out information
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Old 02-04-12, 08:15 AM   #2
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most triple shifters should have a few trim positions
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Old 02-04-12, 08:42 AM   #3
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First and most important, you should not use the 50T chainring with the 27 or even 24T cogs. It's called cross chaning and is hard on the chain and there is no benefit to these gears. A 34x19 gives you almost the same gear as the 50x27 and 34x17 is a good substitute for the 50x24. Second, a double shifter and fd is not going to solve this problem.
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Old 02-04-12, 10:48 AM   #4
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First and most important, you should not use the 50T chainring with the 27 or even 24T cogs. It's called cross chaning and is hard on the chain and there is no benefit to these gears.
+1 Never use those gears, problem solved. Using the big/big and the (much worse!) small/small combinations is really bad for the chain and cassette.
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Old 02-04-12, 11:21 AM   #5
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Sounds like you need a greater number of choices on the low end. Consider swapping back to the triple. To be honest I do not understand why the LBS recommended that change.
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Old 02-04-12, 11:33 AM   #6
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To be honest I do not understand why the LBS recommended that change.
I do. $$$$
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Old 02-04-12, 11:41 AM   #7
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To be honest I do not understand why the LBS recommended that change.
Because unless you are doing lots of hills and heavily loaded like with touring, a compact is less clunky and not as finicky. FD shifts are much smoother. And the bike has 20 gear combo's which is good for just about everything.

I've had several triples over the years and just recently got a compact double on my cyclocross - difference is large.
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Old 02-04-12, 12:29 PM   #8
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Because unless you are doing lots of hills and heavily loaded like with touring, a compact is less clunky and not as finicky. FD shifts are much smoother. And the bike has 20 gear combo's which is good for just about everything.

I've had several triples over the years and just recently got a compact double on my cyclocross - difference is large.
So far the only information we have about riding conditions is his statement that he is having problems riding crossed in big-big. To me that sound like he could be running out of gears on the low end and thus my suggestion that he go back to a triple. I ride 2 bikes, one has a triple and the other a double. So far I haven't noticed the clunkiness in shifting but the rings are apparently well matched for shifting.
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Old 02-04-12, 01:22 PM   #9
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I ride 2 bikes, one has a triple and the other a double. So far I haven't noticed the clunkiness in shifting but the rings are apparently well matched for shifting.
I have triples on all my current bikes but have ridden doubles a fair bit too. I find no differences in the shifting between the two larger rings on a triple than between the two rings on a double. The argument that modern triples are inherently "clunkier" than modern doubles seems unjustified to me. Adjusted properly they shift just as well.
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Old 02-04-12, 02:43 PM   #10
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It is normal to have some chain rub when cross chained. As mentioned above there is no reason to use those combinations. In addition, mixing various generations of Shimano 10 speed can exacerbate this.
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Old 02-04-12, 03:01 PM   #11
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I find no differences in the shifting between the two larger rings on a triple than between the two rings on a double. The argument that modern triples are inherently "clunkier" than modern doubles seems unjustified to me. Adjusted properly they shift just as well.
The differences most people experience and don't like triples as much happen with the small and middle chainring. Agreed, there's not much difference between the two larger ones
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Old 02-04-12, 03:01 PM   #12
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Because unless you are doing lots of hills and heavily loaded like with touring, a compact is less clunky and not as finicky. FD shifts are much smoother. And the bike has 20 gear combo's which is good for just about everything.
2 in the front and 10 in the back = 18 usable gear combinations.
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Old 02-04-12, 05:37 PM   #13
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Thanks for all the replies. I suppose the problem is that this is the first bike I've had that wasn't from the 80's. I don't remember any cross-chaining problems or chain noise on any of the doubles I had back then. Of course they had fewer gears. So problem solved. Use a different combination. I do like the compact. Less for me to deal with. I've been training in a bike shop that has 12 computrainers and caters to racers. I don't really think they've steered me wrong. I've added a little over 100 watts since I've started this past fall and have lost some weight. I live in the mountains and had the triple primarily because I didn't have the legs when I bought my bike. My fitness is better and the compact is fine for my rides now. I don't really remember what the shop charged me to swap out my crank, but it seemed stupidly cheap. They even took my old one in on trade. Now that I know this is common, I'll look more into the gearings and save my cash for a wheelset!

Thanks again.
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