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Suntour derailleur help

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Suntour derailleur help

Old 04-18-10, 12:00 PM
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Suntour derailleur help

Hi gang. Before you tell me to search, I did and still need help. I am currently using a Sprint 9000 group on one of my road bikes with a 13-26 7 speed freewheel. 50/38 crank set. I have some pretty tough rides happening this summer and fall, and I'd like to get a bit lower gearing. Found a 12-28 (my ideal range for the rear) freewheel NIB. I'm curious if anyone can comment on the rear mech handling this tooth capacity. According to the manual, it can do 23 indexing, 26 friction. I use it in friction and it does fine. Other (reliable) sources say the Sprint 9000 rear mech can handle a 28 tooth cog. I should point out that I am very careful about cross chaining as it is and never use the top two cogs with the large ring or the smallest two with the small ring. I'm thinking that if chain length is an issue, but the mech can handle the 28 tooth cog, can I run it and just avoid certain gear combinations with a chain that's a link short? I have no problem using friction if that would help too. My other thought is to find a medium cage XC/XC pro rear mech, but then I would be worried about the DT shifters working with it.

Thanks everyone for any help.
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Old 04-18-10, 12:08 PM
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I don't like running chains that are too short for the big/big chainring/cog combination. Yeah, you never use them, but one moment of fatigue induced oversight shifting into that combo will ruin your day.

The manuals tend to be conservative in describing max cog/chainwrap, so if it works, the proof is in the pudding...

I don't see why there would be any problem running the XC RD with downtube shifters in friction.
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Old 04-18-10, 12:17 PM
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If that was a Shimano derailer I'd say go for it. I just don't know about Suntour cause I've never tried it. I'd say 28 is worth a try. Anything more than 28 I'd say think MTB derailers.
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Old 04-18-10, 12:26 PM
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I agree with robtsu. better safe then sorry. I am sure ou are trying to keep this close to original or period but with friction most any med or longcage RD will work. some thing like a shimano sora or rsx will be great and because of the 'centurion' upper pulley shift a bit smoother perhaps.
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Old 04-18-10, 12:51 PM
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If you are running friction any rear d with the proper capacity will work... Suntour made many medium and long cage friction models that will handle as many as 34 teeth in the rear.

With a Suntour indexed system you are usually limited to Suntour components as they do not play with Shimano parts due to different actuation rates.
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