What bike do you have?
Do you have a double or a triple front?
What is your biggest cassette?

jaretj

Cannondale CADD 8, double front with a 53 tooth largest cassette

Unless you have more than 28 on the back probably short.

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https://www.pbandjcoaching.com
https://www.thisbigroadtrip.com

Just out of curiosity, what problem are you trying to solve by "upgrading" from 105 to Ultegra?

I doubt your cassette has a 53 tooth cog. What's the number of teeth on your largest cog in the rear?

All derailleurs should specify their maximum capacity (which IIRC is limited by the distance the RD needs to go to adjust for all slack). It is usually represented in number of teeth: (large ring teeth) - (small ring teeth) + (large cog teeth) - (small cog teeth). So a 53/39 front and a 12-21 cassette needs an RD with a capacity of at least 23T. I see on the Shimano page that the Ultegra RD has a Total Capacity of 33T; the long cage version has a TC of 41T.

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"Go yell at an M&M"

If your 105 is this one (105 Black) please PM me if you plan to sell it.

trav

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"As for "xxxxxx"...what can I say? You sound like a dick. If you don't want to answer the question, just shut up." AllezPappa

I recently picked up a 105 5701 SS (short cage) to replace a broken Ultegra RD-6600. I got the short cage because that's what it was replacing and I didn't want to change chain length.

FYI I would take the new-gen 105 over an Ultegra 6500 anyday. Just my 2¢.

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Madison photographer Timothy Hughes | Instagram

Sorry the rear cassette largest is 26t and I mispoke, my current derailleur is a Sora. I'm upgrading because...why not?

Short cage but you could use a long cage if you wanted to, it's just a little longer.

Some people like longer ones.

jaretj

After more digging on EBAY I've found some pretty good deals on the Dura Ace RD-7700 an now am wondering if thats the better option over the Ultegra RD-6500. My limited experience tells me that Dura Ace is always better...

Here's what I did when I needed a new Shimano RD a month ago. Upon taking advice from ST, I bought this: http://www.artscyclery.com/...age-SHRD5701SSL.html for $40 and upgraded the pulleys to Dura Ace from the same store. If you want better performance, look into high-grade ceramic pulleys.

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Madison photographer Timothy Hughes | Instagram

Here's the tradeoffs:

Short cage: Lighter, looks more "pro", slightly crisper shifts. Works for up to a 28T (assuming an 11T small cog).

Long Cage: More "cyclotourist" looking (heavier, less aero). Supports triple cranksets up front, and beyond a 28T "dishplate" in back.


Also note if you go to a long cage from a short cage you may need a new chain. Going the other way, just take links out.

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ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)

You've had good experiences with Arts Cyclery?

Asking cuz I've never purchased from them and thinking about it.

jaretj

Don't the newer Shimano short cages actually go higher than 28t rear?

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Ian

On my Felt F5 I've used an 11/32 with a 5701 short cage. Supposed to be good to 30 teeth but I was able to go a little more.

On my P2 I had to go to a long cage to use the 32.

I've purchased a lot of stuff from Art's, they were uneventful transactions and I will buy from them again.

Thanks

I'll defenitly go with a short cage but should I get a Ultegra RD-6500 or the Dura Ace RD-7700. Which one is the better bang for my buck?