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Old 05-20-03, 07:25 AM   #1
Homebrew
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Does frame (road) geometry dictate whether your can run a double or a triple?

Hi all,

I have been reading all I can a debating whether or not to put my triple crankset back on my bike. I have a Jamis Eclipse. Yes, it's a racing bike and shouldn't need a triple. But, I really want that low gearing for the weekends when I'm in the mountains.

Here is the problem:

When I put it on the first time, or one of the LBS put it on it seemed like I could never dial in the derailleurs to make the bike shift a smoothly as I wanted it too. I ran the triple for about a month last year and tried playing with the adjustments and having a bike shop adjust things too. In the end I put my double back on because the shifting was much quiter and smoother.

Last night I brought all my parts and the bike to another shop that seems to have more skilled mechanics and I explained to them what I'm telling y'all now. He said, that some frames weren't as willing to accept a triple crankset because of the length of the chainstays. My chainstays are 410mm. You can find the overall geometry of the bike here: Eclipse geometry.

I mentioned that Lemond sells the Zurich with a triple and I would imagine that most people that buy them have good results with regards to shift performence. He said I couldn't compare the two frame. But when I look at them they seem fairly close. The chainstays on a 55cm Zurich are 415mm. Would that make such a big difference?

If I want to minimize chain rub should I run a narrower chain? What are the pros and cons of a narrower chain?

Lastly, to address the initial question, does frame geometry dictate whether or not you can run a triple crankset?

Thanks,

Sean
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Old 05-20-03, 07:47 AM   #2
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i wouldnt think the geometry would have anything to do with it.

what i can tell you though is that some bikes just don't like certain deraillers. we've had problems in my shop before with bikes equipped with deraillers that just wouldnt work. there's a certain distance the inner cage of the derailler has to be from the center of the seat tube, and these deraillers were just too far away. screwed everything up.
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Old 05-20-03, 08:00 AM   #3
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You might just need a wider bottom bracket to restore the chainline
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Old 05-20-03, 08:19 AM   #4
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FOG,

I'm using a standard Ultegra triple BB.

Has anyone ever put spacers at the top and bottom of a 9 speed Shimano Cassette to optimize chainline?

Basically i want to have the low gears for climbing but retain the middle upper gears for fast riding. I never really use the 12 T cog. I wonder if I could move the 27T cog from the position closest to the bike (position #1????) to the second position and then put a spacer in position one.

Would that work or would I run the risk of accidently shifting to position one and messing up my chain???

Thanks,

Sean
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Old 05-20-03, 08:32 AM   #5
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Try contacting Jamis about the problem. Maybe they can help.
If you can do without the very top gears, and cant make a triple work, it may be worthwhile investigation a low-ratio double. You may need to find a chainset which can work. Specialities TA do a nic eone with a bolt circle of 110mm, which means that you can fit smaller rings. You can make up a 36/48 typical of cyclo-cross machines, or any other combo with a max of 14teeth difference.
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Old 05-20-03, 08:53 AM   #6
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Another issue is that the feather adjustment on Shimano front derailleurs is not available for triples, and may result in the chain rubbing the front derailleur
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Old 05-20-03, 09:45 AM   #7
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Michael,

I'm very much thinking about a Specialties TA Zypher Light crank set in a 48/34. This seems almost perfect. I'd be running a 12-27 cassette which would give me a low gear of 33.1 gear inches. I'd really like a low of 30 GI but that might not be possible.

The only reason I haven't gone to this solution is because it would cost about $315. Otherwise it sounds great.

I'm going to give the triple one more try and if that doesn't work out then I'm going to order the Specialties TA.

Sean
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Old 05-20-03, 09:47 AM   #8
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Quote:
Originally posted by FOG
Another issue is that the feather adjustment on Shimano front derailleurs is not available for triples, and may result in the chain rubbing the front derailleur
What do you mean by the feather adjustment?

Is that the adjustment on the left shifter which allows you to move the front derailleur side to side just a hair without switching chain rings?

Sean
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Old 05-20-03, 09:56 AM   #9
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Another, less expensive alternative to the TA crankset, would be to install a Shimano XT or XTR rear derailluer and cassette. Under a hundred bucks, some great mountain gear inches, and easily converted back to road configuration when needed.
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Old 05-20-03, 10:20 AM   #10
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Quote:
Originally posted by Homebrew
What do you mean by the feather adjustment?

Is that the adjustment on the left shifter which allows you to move the front derailleur side to side just a hair without switching chain rings?

Sean
Yes. This is not a problem with Campagnolo Ergo levers. Does Shimano allow you to feather the front derailleur?
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Old 05-20-03, 10:30 AM   #11
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Steve,

If that is the feather ajustment, then yes. I can do that.
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Old 05-20-03, 10:30 AM   #12
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Quote:
Originally posted by SteveE
Yes. This is not a problem with Campagnolo Ergo levers. Does Shimano allow you to feather the front derailleur?
Yes, it's called trimming.
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Old 05-20-03, 11:09 AM   #13
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Davet,

Have you tried the XT cassette/XT Rear derailleur setup? Can you tell any difference in shifting perfromance between the XT setup and say an Ultegra set up?


Sean
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Old 05-20-03, 11:33 AM   #14
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Quote:
Originally posted by Homebrew
Hi all,
He said, that some frames weren't as willing to accept a triple crankset because of the length of the chainstays. My chainstays are 410mm.
Giant OCR triples have 407mm chainstays
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Old 05-20-03, 11:36 AM   #15
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I've had the XT rear der/cassette set-up on a Serotta, Colnago and currently use it on my Woodrup. My wife also uses it on her Calfee. We have lots of big hills and mountains where we ride in Eastern Washington, Idaho and Montana.

There is a slight shifting performance difference, but nothing big, just not quite as crisp. The jump in the gears as you shift to larger rear cogs get bigger as the cogs get larger, but the ability to sit and spin up most anything road you want outweighs any shifting differences.

We like to do longer rides, 60+ miles, and there are no flats around here that long. Most every road is up or down, so the ability to climb anything is very important to us. It makes the rides more pleasant and less of a chore.

We love the challenge of conquering hills and mountain roads, but when the rides are long we don't need to push as hard.
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Old 05-20-03, 12:36 PM   #16
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Davet,

That's the answer I was looking for. I just went over to my LBS and they said I could use my Ultegra Triple Rear Derailleur with an XT cassette. Ever try that?

Sean
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Old 05-20-03, 12:54 PM   #17
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Depending on the size of the largest cog on the XT cassette, the Ultegra der may not clear the cog. The B screw won't provide enough adjustment. It's not a matter of chainwrap, it's physical clearance.
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Old 05-20-03, 12:57 PM   #18
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Do I have to stick with a 12-x or can I go with an 11-x XT cassette. I thought I had read somewhere on Sheldon Brown's site that if you choose an 11T cog then you have to add an extra piece of hardware onto the cassette?

Does that make sense?
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Old 05-20-03, 02:28 PM   #19
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Cassetts that use 11t cogs need a special lockring. The lockring comes with the cassette when you buy it.

If you are going to use an 11-32 or 11-34 cassette, you will need to use a MTB rear derailluer. I believe the Ultegra rear der has max capacity of a 30t cog.
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Old 05-20-03, 03:01 PM   #20
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Thanks for all you help Davet.
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