Chain rings

[Badger]

Originaly On my Cannondale T2000 I had 52/42/30.  I changed that to a 48/39/30 however after reading some of the discussions I'm beginning to think that the 30t is a little tall for touring.  I can go to a 28t or 26t chainring but my real question is will there be shifting problems using this small of a chain ring?

[wanderingwheel]

Because you also reduced the size of your big chainring, you may want to consider removing a link or two from your chain.  Otherwise it should shift fine.  It is possible to have problems if the jump between chainrings is too large, but you already reduced the size of your middle chainring so it should not be a concern of yours.

Sean

[biker_james]

My wife and I have T800's that came with 52/42/30. I swapped the rings on hers to get a 24/39/48, and I changed the cranks on mine and have a 22/38/48. They shift fine-I will say that you may want to just take an extra second when shifting up from or down to the granny ring as it is a big drop. I haven't had any more problems with it throwing the chain or that than I had with the original rings. Going to a 38 middle is great too-you don't need the granny ring near as much, but when you do you have low enough gears for anything. Of note-the bikes came with Tiagra shifters, but we replaced them this year with Ultegra's-same ones you have I believe.

[RussellSeaton]

Put on the smallest inner chainring you can, 24 tooth in your case.  And put on a chain watcher device to reduce the occurences of the chain dropping onto the bottom bracket shell when shifting down to the inner chainring.  It happens no matter how well you think your bike is adjusted.  Third Eye Chain Watcher, N-Gear Jump Stop are two of the chain watchers.  STI is not gentle about downshifting the front derailleur.  You click the STI and it throws the chain very suddenly down to the smaller ring.  The smaller the ring for the chain to land on, and the bigger the difference between rings, the more likely the chain is to miss.  A chain watcher is good, cheap insurance.

My Trek 520 came from the factory with 50-45-28 rings.  I had the shop put on a 24 instead of the 28 before I bought it.  Later I switched the 50 for a 48.  Then I switched the 24 for a 20, using a special adaptor.  Finally I switched the 48 for a 42.  Now the bike has 45-42-20 rings.  I use bar end shifters so it shifted fine enough with all chainring configurations.

[driftlessregion]

I agree with Russell. I use the Third Eye with a 24 and STI shifters when touring loaded (otherwise I have on the 30). Be sure to ride with it loaded on hills before you leave for a long tour because there is a best position for the device that you must find. I got a chain stuck under it before I got it adjusted properly. Also, practice shifting on the hills, shifting early, before it is a must shift down NOW. That will help aim the chain to the little chainring.

[Badger]

Yes I'm aware of what they call chain suck,  I had the problem with my cannondale when I first got it, especially when trying to down shift going up a hill.  Stops me real fast and the ground and myself met.

[RussellSeaton]

Chain suck is different than dropping the chain while shifting down to the inner chainring.  Chain suck occurs when the chain is stuck/sucked/glued to the backside of the chainring when you try to shift.  Instead of the chain going straight back to the rear derailleur from the bottom side of the chainring, it sticks to the chainring and goes up and tries to cover 100% (top, front, bottom, back) of the chainring instead of just 75% (top, front, bottom).  Then the chain gets sucked into the underside of the chainstays.  I believe chain suck is mostly caused by mud, dirt, etc. which is common in mountain biking.  You usually have to work at it to get chain suck with a paved road bike.

[bentrider1a]

RUSSELL, WHAT KIND OF SPECIAL ADAPTOR DID YOU USE TO GO FROM 24 TO 20 TOOTH?  NAME?  WHERE DID YOU GET IT?
ANY INFO WOULD BE GREAT!
THANKS

Steve
2002 GOLDRUSH

[RussellSeaton]

http://www.bikepro.com/ad_copy/crank_crings_chard.html

http://www.bikepro.com/products/cranks/cogs-rings-&-bolts.html

Avid Microdaptor-2 or Micro Adaptor or something like that.  See websites above.  It works by replacing the spacer washers used to move the inner chainring into the right place.  This adaptor becomes the spacer for the inner chainring and it has bolt holes at the 58mm bcd position for the 20 tooth inner ring.

Please note, that this adaptor only works on cranksets with 74mm inner 5 arms AND removable spacers for the inner chainring.  Very, very, very few triple cranksets sold in the past 10 years have removable inner spacers.  Almost all have the inner chainring spacers forged into the body of the crankset.  These are the 5 lugs sticking out when you look at newer cranksets.  My old 1991 Deore DX 110/74 bcd crankset has the inner chainring spacers as thick washers.  Remove the inner chainring and the 5 spacer washers come off.  Most likely you will have to find an older triple crankset with removable spacers to use this adaptor from Avid.

And I am not sure Avid still makes the adaptor.  I think its been out of production for a few years or more.  I bought mine from Cambria Bike Outfitters about 7 years ago.

This message was edited by RussellSeaton on 2-9-06 @ 12:33 PM

[bentrider1a]

Russell,  thanks for info I'll see if it will fit



Steve
2002 GOLDRUSH