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Old 10-05-09, 12:08 PM   #1
john_h
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Upshifting and the type of chainring pins required?

Hey folks,

So I've taken the jump and assembled my first bike from scratch (09 Soma Smoothie ES). I'm having some difficulty with upshifting smoothly from the inner to middle chainring and suspect I need a middle chainring with a different pin type. Some background on the setup:

Sugino XD2 cranks
IRD alpina triple FD
48-36-24 chainrings
105 9-speed shifters (5510 model me thinks)
9 speed Tiagra RD
11-28 SRAM cassettte with SRAM chain.

The middle chainring has ramps and round pins. I can get it to shift from inner to middle ringss with about 1 1/2 pushes on the shifter, but occasionally it will jump to the outer chainring (when i push too much on the 1/2 push and it goes from a 2 click to 3 click upshift). When I compare this to the middle chainring on my other bike (07' Ultegra Triple), these pins are more rectangular and have a pronounced tooth that quite readily grab the chain on upshift. upshift from middle to outer chainring is smooth.

I have researched and tinkered greatly with my FD height, angle, inner plate position relative to the chain, low and high limits, and feel that I've got it in the proper position.

With all that said, would you suspect it's the type of pins on the middle chainring that are the culprit?

Many thanks for the input and education!!
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Old 10-05-09, 12:43 PM   #2
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Although I'm not entirely familiar with your setup (and I didn't read it in your post) have you played with the cable tension on the FD?

Although a full shimano (rings, FD, shifters) front will shift most optimally, I don't see why it wouldn't be possible to get acceptable shifting from the current setup.

The FD adjustments will be a lot more finicky, non-shimano and a triple, but should be doable. I don't see why the pins and ramps would be an issue.

Also the Alpina's come in a drop bar and flat bar style (although I'm sure you have the d/drop style).

I would completely disconnect the FD wire, adjust your H/L limits, pull the wire slightly taught, tighten it down, and then adjust the tension until the shifting improves.
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Old 10-05-09, 01:06 PM   #3
john_h
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Yes, I did adjust the indexing a bunch. the shimano setup has the more pronounced ramps and grabs the chain very easily, I'm kinda figuring it may be simply that.

Last edited by john_h; 10-05-09 at 03:09 PM.
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Old 10-05-09, 04:34 PM   #4
zzyzx_xyzzy
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Another thing to consider is chainring timing. 24/36 is a 2:3 ratio and should shift really smoothly.... IF the chainring timing is right.

Do test shifts on the workstand and pause in the middle of the shift while the chain is engaging both the 24 and 36t. The chain rollers should naturally slot between the teeth on the 36t while the chain is still engaging the 24t, and not ride up on top of the teeth. If the chain rides on top of the teeth on the 36t, rotate the granny ring by one bolt and try again. Often one of the 5 orientations of the granny ring works a lot better than the others.
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Old 10-05-09, 05:31 PM   #5
john_h
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Great! That's another question I had that I couldn't find specific info on... The chain does appear to not mate especially well, so i'll try your suggestion tomorrow

I did find out that I didn't tighten my crank bolts tight enough, and that did help improve the shifting slightly. Many thanks!
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Old 10-05-09, 07:41 PM   #6
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shimano designed the system with a 30t small ring and called it a racing triple. The genuses there couldn't figure out how to make the 24 work so they didn't use it.
When you go to the 24 the shift will not be as slick as the stock gearing, but it will work.
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