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Old 05-28-07, 10:02 AM   #1
Terrapin Tim
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Road Bike Climbing Gears...

My currnet road bike is a Felt f90 with Ultegra 9 speed (12 - 25) rear cluster and a triple front set up.

I am training for the SF -> L.A Aids Charity ride for 2008 and After a training ride along the CA coast this weeekned I am looking to add some hill climb gearing. (these 50 year old legs just couldn't keep up with my 25 year old mind even in first gear ).

I have seen mountain bikes with what appears to be a seprate climbing sprocket (40 tooth ????) ... would it be possible to loose the 12 tooth bottom gear and add the monster climber on the inside of the remaining gear stack i.e make it a 13-40 ???? What about RD... it is a long cage triple..... will that have ample capacity for the large rear sprocket as long as I stay off the midle or outer front chain rings ???

Thanks in Advance

Terrapin Tim
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Old 05-28-07, 10:11 AM   #2
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You could put a nine speed mountain bike cassette on the bike, available in either 11 x 32 or 11 x 34 configurations. You would likely need an mtb rear derailleur as well to handle a large cog that big. This setup will index just fine with your nine speed shifters. What you would be losing is the closer ratios of your "road" cassette-
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Old 05-28-07, 10:35 AM   #3
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MTB Cassette

Thats why I was lloking to see if there was an add on tall sprocket... the one I saw looked to be seperate from the main body of the gear stack.... hoping to have the best of both worlds... Close ratio and a super climbing gear

Tim
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Old 05-28-07, 10:44 AM   #4
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Quote:
Originally Posted by Terrapin Tim
Thats why I was lloking to see if there was an add on tall sprocket... the one I saw looked to be seperate from the main body of the gear stack.... hoping to have the best of both worlds... Close ratio and a super climbing gear

Tim
I dunno if you could do that or not. Even if you could find a forty-tooth cog and put it on the cassette (I have no idea), I don't know what rear derailleur would handle it. Current Shimano mtb RD's are rated for 34t max cog capacity (older ones even less, generally). You can probably get away with a larger cog than that on most bikes (derailleur hanger geometry will affect this), but 6 more teeth? I don't know. Current Shimano "road" RD's are rated for max cog of 27t, most report getting away with 30t cog just fine, beyond that is questionable-
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Old 05-28-07, 11:09 AM   #5
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It's do-able but probably not as simply as you might think.

I suspect that what you have seen is a Shimano megarange cassette. They have a bail-out cog that jumps from 26t to 34t which I think is a pretty good idea. Unfortunately for you, it doesn't come as a 9-speed.

Making your own isn't as simple as it looks at a first glance. The first position cogs are different from the other cogs so you can't just throw away the 11 and add a 34 on the other end of the stack. Ultegra and XT cassettes use carriers for the largest cogs so you can't replace the individual cogs easily. Easiest would be to buy an 11/34 or a 12/34 mountain bike cassette.

That brings us to the rear derailleur. Your Ultegra derailleur, even the long cage version, isn't going to work with a 34t big cog so you'll need to get a mountain rear derailleur too.

Finally, you're going to need a new, longer chain to safely cover the big/big combination.
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Old 05-28-07, 04:12 PM   #6
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Maybe a better strategy would be to check your options with the front chainrings. If there's room to shift them all down, you may find the gearing better suited to you. I'm not a high horsepower kind of guy, and 12T rear cogs have absolutely no use to me.
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Old 05-28-07, 04:15 PM   #7
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Shimano has a standard nine speed 12\27, which would give you a bit more relief.
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Old 05-28-07, 05:33 PM   #8
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I believe you could add a 34T bail-out gear, but you can't drop the 12T top gear, as the top gear has the spacer built in. You'd have to drop one of the intermediate gears, which would probably work out fine. Harris has individual 34T sprockets for $9.95:

http://sheldonbrown.com/harris/k7.html#sprockets

I suppose you could buy a larger first gear to replace your 12T too, but then you're spending more money.

As noted previously, you'll need a "mountain" derailer to handle a 34T sprocket.
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Old 05-28-07, 05:42 PM   #9
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http://sheldonbrown.com/harris/k7.html

The CS922 Century Special will give you a bailout of 30T and still
work with your existing gear. Might be worth a try.

You can also throw a 28T ring up front. but it won't shift quite as well.
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Old 05-28-07, 05:51 PM   #10
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Go to a 12-27 cassette to give you a little better low end (30-27 = approx 30 gear inches, vs 32.4 at 30-25) and, since the ride isn't till 2008, train climbing them hills. If you ride em, you'll get stronger.
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Old 05-28-07, 06:04 PM   #11
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Thinking a bit more about this, adding a 30T bailout gear and dropping the 14 will give you :

12, 13, 15, 17, 19, 21, 23, 25, 30

The 30T should work with your existing RD, and your total investment is $10. If that isn't enough, you can always go to a smaller granny up front, as suggested above.
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Old 05-28-07, 06:57 PM   #12
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Great Solution....

You folks are awesome... thanks for all of the feedback....

OK Riding the hils a lot more .... Definitely....

I like the idea of adding the 30 tooth and loosing the 14... seems like this will give a good spread and allows me to keep the existing casette, RD, and Shifters.... spend $10 save $400....

If I still want to get more help on the inclines... what type of shifting problems can I expect if i drop to a 28 t inner chaniring??


TT
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Old 05-28-07, 07:07 PM   #13
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I'm setting up an old Miyata for a charity ride in two weeks over some stiffish Maine hills and geared it 53/40 Biopace up front and 13-30 in the rear. Being a C&V type, I'm limited to a seven cog rear, so you should have plenty to play with having two extra cogs and all.
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Old 05-28-07, 08:05 PM   #14
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Shifting from the 25t to a 30t will be problematic. The ramps are not made for that big a jump.
You could put on a 12-27, or get a 28t cog from Harris. That'll shift ok. Then also put on a 28t or 26t granny ring on the front. Use the gearing calculator on sheldonbrown.com.
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Old 05-28-07, 08:54 PM   #15
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Quote:
Originally Posted by ericm979
Shifting from the 25t to a 30t will be problematic. The ramps are not made for that big a jump.
I've never done it, so you may very well be right, but a number of Shimano's standard mountain cassettes make a 4-tooth jump in this general range (24 to 28, 26 to 30). I would expect you'd want to lighten up the pressure when making a 5-tooth jump, but I would think it would shift OK.

But again, I've never done it. What sort of problems have you run into?
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Old 05-28-07, 09:33 PM   #16
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Looking at the Felt website, the F-90 (2006) is an 8 speed? Did you upgrade to 9?
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Old 05-29-07, 09:13 AM   #17
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Along these same lines, I've got a Shimano 105 9-speed 12-23 on the rear. I've had my eye on the Ultegra 12-27, but if I could just add a 27 tooth gear and drop one in the middle that would be great. Where can I find just a 27 tooth gear (cheap)?
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Old 05-29-07, 09:21 AM   #18
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Originally Posted by Cain
Where can I find just a 27 tooth gear (cheap)?

I dropped the 14t and added a 29t on my 9spd from here: http://www.jensonusa.com/store/produ...Speed+Cog.aspx
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Old 05-29-07, 04:40 PM   #19
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Upgraded to 9 speed

Quote:
Originally Posted by Bill Kapaun
Looking at the Felt website, the F-90 (2006) is an 8 speed? Did you upgrade to 9?

Right you are it came with 8 spd sora components... A friend upgrade his bike to 10 speed and passed along RD, Casette and shifters for free... LUCKY ME....
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