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chainring change(14 posts)

chainring changezeke
Jan 30, 2002 10:23 PM
I have recently purchased a road bike with an Ultegra triple (52-42-30T) with STI, and find that this set is still inadequate for hills I need to climb. To solve this problem, I am considering changing to a 48-38-24T configuration made by TA (a french company?). I have 2 questions:
1. Will the shifting with the TA rings be as smooth as with the original shimano equipment? and
2. The granny gear on the TA set has 24 teeth, while the shimano ultegra has 30 teeth. Will 6 teeth less make a 'significant' difference in hill climbing?
Thanks.
Cogs?Andy M-S
Jan 31, 2002 6:10 AM
It's a whole lot easier to change out your cassette. What are you running in back right now?
Cogs?zeke
Jan 31, 2002 11:24 PM
ive got to check and will get back to you.
also, thanks for the info, ive got to consider cogs.
Cogs?zeke
Feb 1, 2002 12:05 AM
in the back ive got an ultegra 6500 12-27 cassette.
re: chainring changeChen2
Jan 31, 2002 7:10 AM
Do those TA rings come in a triple crank set? If so I would appreciate the URL or source of your information. If the rings are not made specifically for a triple they probably won't shift well. Another thing to consider is your front derailleur. If it is a clamp-on you will be able to lower it enough, if it is a braze-on type it may or may not move low enough. The triple Ultegra derailleur's curvature is made for a 52, it will probably be ok but may not be ideal for a 48. Yes, the 24t will give you much more climbing power.
You could probably have a cassette made (or make it yourself) with bigger cogs. Your rear derailleur can probably handle a 29, maybe even a 30. Changing the cassette would be the easier conversion. Sheldon Brown makes custom cassettes, www.sheldonbrown.com.
-Al
re: chainring changezeke
Jan 31, 2002 11:32 PM
yes, they do. check peter white's site http://www.peterwhitecycles.com/.
also, sheldon brown's harris cyclery sells TA chainrings individually.
according to the peter-white site, the TA chainrings are made for a triple in that they are 'pinned', therefore, according to the description, the shifting should be smooth. my fd clamp is a clamp on.
i hadnt realized that the fd is curved specifically for 52T. i will seriously consider changing the cassette. will i get the same effect, ie changing the cassette rather than the chainrings? i am more interested in climbing hills and distance, than running at high speed.
You are SOLpmf1
Jan 31, 2002 7:16 AM
TA chain rings will not work on the Ultegra triple. The 52/42 rings you have are ramped. The standard Shimano and TA rings are not. I tried to put a standard 39 on my wife's triple and it would not shift out of the small ring. I suspect the same would be true if a standard large ring were installed. Shimano does not make a ramped 39 ring although I see that the DA triple is 53/39.

You must live near some pretty darn steep stuff for a 30x27 not to be adequate.

One thing you could do would be to install an XT rear derailer and use a bigger mtn bike cassette. I hear people do this.

Another might be to try a smaller inner ring (the smallest one does not need to be ramped)
You are SOLzeke
Jan 31, 2002 11:38 PM
by 'ramped' do you mean 'pinned'? its true that the standard shimano and ta are not pinned.

i live at the foothills of the japanese alps. i can easily go 20k on relatively flat land, but to escape the trucks, i need to/want enter mountain roads.

is it possible to change only the inner (granny) TA ring and have it shift smoothly back to the middle shimano ring?
Another solution.....Len J
Jan 31, 2002 8:14 AM
Leave the chainrings alone.

Replace the rear Der with an Shimano XT or XTR long cage. This will allow you to rplace the rear casette with up to a 34 tooth ring. a 30x34 will give you exactly the same gearing as a 24X27 (27 being the largest rear cog recommended by shimano for thier road Der.) Shifting will be great.

Len
Another solution.....zeke
Jan 31, 2002 11:42 PM
thanks for the advice. according to a couple of other responders changing the cog seems to be the way to go. i dont want to mess with adjusting a front der. if i change chainrings.

so as for changing the cog-set, all i need do is purchase a new set (eg xt or xtr) and replace it for the ultegra 9-speed? its that simple?
NoLen J
Feb 1, 2002 4:25 AM
With Ultegra, You might be able to go from a 12-27 to a 12-28 maximum. The Ultegra rear Der. won't handle more than 28 teeth (& that is one tooth beyond what Shimano recommends) There are some on this forum that believe you can stretch it to 30 teeth but I have never seen that work effectively.

What I am recommending is to replace the road rear der. with a mountain bike rear der. (The XT 0r The XTR). These are completely compatible with your existing STI shifting. And then replace the cog.

Replace the Rear Ultegra DER. with aan XT or XTR der. (Probably need the long cage) (About $50.00 for an XT)
Replace the 12-27 cog with a 13-34 XT cog. (About $45.00)
Lengthen the chain.

I would recommend that if you haven't done this before either get a book like Zinn & the art of road bike maintenance or let your LBS do this for you.

Len
Nozeke
Feb 1, 2002 1:15 PM
thanks for the very detailed advice.
i do have the zinn and it seems that i can do it myself.
"lengthen the chain" this is new info.
thanks again.
Lengthen Chain...Len J
Feb 1, 2002 1:29 PM
I probably wasn't clear. Just check your chain length (as Zinn would suggest. A 52 X 34 is probably going to require more chain than a 52 X 27.

Len
Lengthen Chain...zeke
Feb 4, 2002 11:10 PM
your response was clear.
i am now reconsidering whether i want to change the cassette. i didnt realize other changes needed to be made.
thanks for the informtion.