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what am I doing wrong?(15 posts)

what am I doing wrong?stan_b
Oct 16, 2002 4:57 AM
I recently went from an Allez Elite with a triple to a Jamis Eclipse with a double. With the Elite I spent most of my time using the 42 tooth middle chainring. Now I find I am having to constantly shift between my 39 and 52.

If I'm in the 52, I find I'm constantly inclined toward the bigger rings in back and the subsequent rubbing on the front derailler. If I'm in the 39, I find I want to use the small rings in the back and again rubbing on the front derailler.

I feel like I'm almost ready to get a triple again just to avoid all the front derailler shifting. Any suggestions would be appreciated!
stupid question time...ClydeTri
Oct 16, 2002 5:21 AM
is not possible to switch the 39 ring to a 42 ring?...another option, maybe change the cassette configuration to reflect better your riding style
Easy there, bud... it's a legit question. (nm)OffTheBack
Oct 16, 2002 5:30 AM
I meant ..ClydeTri
Oct 16, 2002 5:53 AM
I meant mine was potentially a stupid question..not his
stupid question time...stan_b
Oct 16, 2002 6:04 AM
That of course would be possible but I need the lower gears of the 39. In fact, I already changed what came with the bike. I got rid of the 53/39 and 11/23 set up and went with 52/39 and 12/27.

It just may take more getting used to as I've only ridden the new bike twice. I'm more inclined to just keep it in the big ring but I like high cadence and tend to have knee problems so I know I shouldn't be pushing high gears all the time.
re: Cheap route is to tryJL
Oct 16, 2002 5:29 AM
checking with Sheldon Browns gear calculater:

http://www.sheldonbrown.com/gears/index.html

Do some gear range comparisons between the two bikes to see where you "usually" ride. Then you can work shifting the double in comparison to your old triple. You may want to change the rear cogs to something that will give you something similar to the Allez as ClydeTri suggested. I would do some gear calcs first to see what you're looking for.

Happy riding.

John
Front mech rubbing? Some fine tuning required..Spunout
Oct 16, 2002 6:14 AM
If not in the extreme angles of chain line.

Are you needing bigger or smaller gears in general? This may reflect your cog selection to give you a comfortable range in the middle of the stack.

Other than that, do lots of shifting! Get stronger, and ride all day in the 52!
adjust the front derailleurbigrider
Oct 16, 2002 6:15 AM
There are a couple of things to try. First, I believe there is a trim adjustment on the shimano shifter which means you can make a mini adjustment on the derailleur without changing rings. If you adjust you limits right, angle your derailleur properly, and trim your derailleur when needed you should have minimal problems.

The only other thing I can think of is make sure your crank is on the BB straight so your chain is not moving back and forth as you turn the crank.
trimmingmadwiscbiker
Oct 16, 2002 7:24 AM
are you talking about an adjustment while riding or while you are setting up the derauilleur? Can you speak to this a bit more.
trimmingbigrider
Oct 16, 2002 7:36 AM
The shifter has a trim where if you slightly press the lever it will move the derailleur a small amount, not a shift. If you adjust your big ring/small cog first and have the smallest gap possible between the chain and derailleur and then shift to the small ring/large cog you should still not rub. You may have to hit the shifter three times instead of two for the trim.

Adjust your derailleur limits (the screws) prior to adjusting cable tension. Make sure they are tight enough not to let the chain get thrown but large enough not to have chain rub when in the above mentioned combos.
Trimming the front der. is often required at the margins . . .Look381i
Oct 16, 2002 6:33 AM
I have Campy 10-speed. I find the middle cogs useful and use them a lot with both chain rings. But when I shift to the more extreme ones (avoiding cross-chaining), I will usually trim the front slightly to avoid chain rub.

With a typical cassette, say 12-23 or so, you should find that shifting to a different ring will equate to about a two- or three-cog shift in the back.
Here's a different possibilityTig
Oct 16, 2002 7:15 AM
My suggestion applies only if the derailleur adjustment has been thoroughly worked with and no positive results can be achieved. It could have something to do with the width of the front derailleur's cage being too narrow. It takes only a slight narrowing to cause this kind of problem. Not by design, but by damage. I like to pride myself in my ability to adjust derailleurs to near perfection, but my old 105 front had similar problems. It ended up being caused by the flimsy construction of its cage allowing it to be squeezed too narrow when I had to perform a road side fix. Pushing my thumb against the side of the cage while tightening the cable's lock bolt was the actual culprit.

After spreading the width a little by expanding a large set of needle nose pliers in the middle, and the problem was gone. A later upgrade to Dura Ace was an even better fix!

Also, check out the Park Tools repair guide at http://www.parktool.com/repair_help/howfix_frontderailleur.shtml
Could just be a matter of acclimating but....joekm
Oct 16, 2002 7:35 AM
Sounds like it's just you getting used to the new setup. 53/39 on the front is pretty standard for a dual. Usually there is some overlap at the gears so it might be worth it to work up a gear-inch chart so you can re-evaluate your shifting strategy in light of the new drive train. Possible resource is:

http://www.pagesz.net/~scotty/gear-form.html

Going to the 12/27 cog might have been a good idea as well. My bike came with an 11/23 as well and I'm considering getting a 12/27 for hills.
Cassette?Chen2
Oct 16, 2002 8:23 AM
Changing to a 13-25 cassette would give you a better selection of mid-range ratios, but if you need a 27 you need a 27. It's also possible to convert your 12-27 to a 13-27 by replacing the 12 with a 13 with built-in spacer and adding a 16 in the middle. The parts are available at www.sheldonbrown.com. Another option would be to replace your big ring with a 50t.
~Al
Possible cable stretch...Slip Stream
Oct 16, 2002 12:27 PM
Since your bike is new, the cables will stretch. Bike mechs will tell you most stretching occurs in the first 300-500 miles. That is why shops offer a 30 day tune up for break in. Stretched cables will throw out your limits a little. If you can't wait that long - check your upper and lower limit set screw on your front derailure. It is not something you have to adjust often. Once set correctly it will last at least 1K miles. If you need help adjusting with the limit screws, don't be afraid to ask for help.