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Old 03-29-12, 08:24 AM   #1
WheelsNT
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Where to find 42T middle chainring w/ramps in 110 BCD?

Hi Friends --

I recently got a Trek T200, and I'm updating the drivetrain. Happily, it's 145 OLD at the back, so I am able to easily go to 9 speed. I've added Ultegra 9 speed STI brifters, a SRAM 9 speed cassette, and new chains. The rear shifts great with the XT derailer. However, the front is a little slow both from the inner 30T to the middle 42T, and also from the 42T back to the 30T. I have tweaked the cage on the stock 8 speed 105 front derailer to narrow it for the 9 speed chain, which helped. But I think having a ramped, pinned, and gated 42T would help a lot -- the stock chainring does not have ramps and pins. Problem is, the cranks are the Sugino XD tandem cranks, which are 110 BCD. Where can I obtain a ramped and pinned 42T in 110 BCD for a reasonable cost?

Thanks!
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Old 03-29-12, 08:41 AM   #2
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I'm hoping you get some good responses. My one observation is that the 42 to 30 shift has nothing to do with the ramps so I'm thinking your FD might have something to do with this. I've not paid much attention to the ramps on my chainrings, but assuming that the ramps are directionally-specific I'd be surprised if manufacturers made chainrings specifically for tandems.
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Old 03-29-12, 09:12 AM   #3
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You do not mention the size of your big ring however I would consider getting a 39 tooth middle triple which would be easier to find.

Good selection here:
http://sheldonbrown.com/harris/chainrings/110.html

I agree shifting down from middle to small ring may be the FD setup. I have had good luck with both Shimano 105s and Ultegras. Sometimes rotating the FD so that the cage is very slightly angled with the tail of the cage inboard of the front of the cage does the trick.

A Campy left shifter also helps

Last edited by waynesulak; 03-29-12 at 09:16 AM.
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Old 03-29-12, 09:47 AM   #4
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TA Specialties makes a wide variety of chainrings, and Peter White Cycles has a very complete listing. Does this do it?

Quote:
Originally Posted by Peter White Cycles
Specialites TA Zephyr

TA 110mm bolt circle chainrings

Middle Position 110 (silver finish)

Middle position chainrings can be used in both double and triple configurations. But of course the pins are not needed for doubles.

Specialites TA 42 tooth pinned for STI 9 or 10 speed compatibility
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Old 03-29-12, 10:09 AM   #5
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Hold out for the 42T ring the ratios are much better than with a 39T middle. I've used the TA rings and they are very good. Raceface used to make nice tandem rings too - I had a 44T/110mm. Good if you can find it.
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Old 03-29-12, 10:16 AM   #6
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Quote:
Originally Posted by waynesulak View Post
You do not mention the size of your big ring however I would consider getting a 39 tooth middle triple which would be easier to find.

Good selection here:
http://sheldonbrown.com/harris/chainrings/110.html

I agree shifting down from middle to small ring may be the FD setup. I have had good luck with both Shimano 105s and Ultegras. Sometimes rotating the FD so that the cage is very slightly angled with the tail of the cage inboard of the front of the cage does the trick.

A Campy left shifter also helps
Thanks for your suggestions!

The 39T option would definitely mean getting a new front derailer since the 105 8 and 9 speed were designed for a ~10 tooth difference between the middle and outer rings (42-52), while the 105/Ultegra 10 speed derailers are designed for a 14 tooth difference (39-53). I also like how the 42 works for us - I think the 39 would mean many more shifts to the large ring, whereas the 42 lets us stay in the middle much of the time.

I had seen the Harris Cyclery page and also Peter White here:

http://www.peterwhitecycles.com/chainrings.asp

Peter White definitely identifies "middle" rings which would seem to indicate that they are ramped and pinned to help the shift from the small ring on a triple. Harris says "inner/middle" which made me wonder a little. But both of them are selling TA rings, and those are the only ones I have seen available for sale in the USA. If I wanted to order from Europe, I could try to get Stronglight. And that's all the options I know about -- I am hoping that there's another domestic source I haven't considered.

I agree that the ramps and pins won't help the middle-to-inner shift, but I thought the gates helped the shifts both ways -- the shorter teeth giving a place to grab the chain on the way up and a place to release it on the way down.

The other issue is that when I have aggressively adjusted the inside FD stop to make the downshift snappy, the chain sometimes gets thrown to the inside if the inner ring. Sugino cranks have a slightly different chainring spacing than Shimano, and also it's an 8-speed crank with a 9-speed chain. I don't know if either or both of those factors are contributing. I do have an N-Gear Jump Stop on order, which might help.
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Old 03-29-12, 10:38 AM   #7
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Quote:
Originally Posted by waynesulak View Post
I agree shifting down from middle to small ring may be the FD setup. I have had good luck with both Shimano 105s and Ultegras. Sometimes rotating the FD so that the cage is very slightly angled with the tail of the cage inboard of the front of the cage does the trick.
I will definitely try moving the tail in. Thanks!
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Old 03-29-12, 10:49 AM   #8
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There is also XXCycles, the exclusive source of highly regarded Stronglight chainrings. The trouble is, the website is confusing and non-informative, and emailing them doesn't help.

Is this 110/74 CT2 Type S/H MIDDLE pinned? No telling.
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Old 03-29-12, 11:16 AM   #9
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Quote:
Originally Posted by waynesulak View Post
A Campy left shifter also helps
Wayne, that's a low blow. True, but low
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Old 03-29-12, 05:33 PM   #10
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http://sheldonbrown.com/harris/chainrings/110.html
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