Will this Work? If so, How?
 

I have a Cannondale CAAD8 Optimo 1 Triple with a Shimano Ultegra FC-6603, 10-Speed, 52-39-30 crank. I upgraded to the Shimano from the stock TruVativ Elita 3.2 crank.

I am thinking of swapping the 39t middle chainring with a 42t middle chainring. By the way, the front derailleur is a Shimano 105.

My questions are these:

1) I can't, for the life of me, find a 42t, 10-Speed, FC-6603 Shimano Ultegra chainring on the web;

2) Can I make this work, If I can find the chainring?;

3) Am I setting myself up for shifting problems? I mean, am I going to have problems with either the shift from the 30t ring to the 42t ring, or vice versa; or are there gonna be problems with the 42t ring shift to the 52t or vice versa?

4) If I do get my hands on an appropriate 42t, 10-Speed chainring, am I gonna have to lengthen my present chain to cover all my gear shiftings, or can I keep my present chain-length?

5) Can somebody hook me up with a link to where I can find the appropriate 42t chainring?

I am thinking the sweet spot for my cycling is gonna be found with a 42t 10-Speed middle chainring. I may be wrong, but I am willing to try and find out, especially if it's not gonna cost me my first-born child.

I am currently a little over half-way recovered from a badly-broken femur, hence my experiment. The 39t is too easy, the 52t is hard, and the 30t is exclusively reserved for hills. I still cannot stand up and pedal up hills, but things are getting better each day.

Thanks for all responses.

Regards,

1. Try Shimano's web site. If they don't list it they don't make it.

2. Sure but the front derailleur won't be ideal

3. The shift from the 30 to the middle probably won't change. The fd might have interference problems with the larger 42T middle and you may have to raise it to clear. That will make the shifting worse.

4. No. Chain length is determined by the largest chainring and largest cog. The smaller ones don't matter.

5. No clue. Try a 9-speed ring?

QBP carries a 5/130 42t Ultegra FC6503 chainring. They don't show a 105 42t ring.

Talk to your LBS to order.

The stuff about "n-speed" chainrings is mostly marketing hype, don't worry about it.

You do want a "middle" 42 so it will have the ramps and pins to help upshift from the 30 (or other small ring, if you wind up upgrading your bottom end.)

For the front derailer, ideally you want a "9-speed" model, not the "10-speed" version. This actually isn't about the chain width, it's about the 39-52 jump vs the 42-52 jump.

The "10-speed" model has a deeper inner cage plate. To use it with a 42, you will need to raise it up to keep the inner plate from bumping into the teeth of the 42. The higher mounting will degrade shifting to the 52.

Maybe you should consider going to a tighter cassette instead.

See: http://sheldonbrown.com/gears and run some numbers.

You don't need to change the chain, because chain length is set to the _big_ ring, and you're not changing that.

Sheldon "Gears" Brown

30-39-52 is actually a much more even progression than 30-42-52. I think that's why Shimano has started making them that way.

I agree with Mr. Brown...perhaps look at tightening up your rear cassette. Or loosening it to make the 52t "easier".

Thank you all for the practical responses. I think I'll take Mr. Brown's advice, run some numbers on his gear calculator, and start playing around with different cassettes to see what I can come up with.

The problem I do foresee is cost. I have Dura-Ace FH-7800, 10-Speed rear hubs, and they just do not work with cheap cassettes.

Once again, thanks to all that responded.

Regards,

The tightest Ultegra cassette Shimano makes is (11-23)t. Am I gonna notice much difference between this cassette and my currently installed (12-25)t cassette?

Also, I assume my present chainlength does not need any shortening in going to a (11-23)t from a (12-25)t.

Assumption correct?

Regards,

Yes.

Maybe. Measure it.

Basically, you'll be giving up your lowest gear, for no benefit. If you live in the flatlands, that's no problem, but you wont have any use for the 11 if you're running full sized wheels and a typical "road" chainwheel set.

The chain length won't be an issue, but if your present chain has more than a few hundred miles on it you should replace it anyway...generally good practice to replace the chain when installing a new cluster.

Sheldon "11? Why?" Brown

Thanks Sheldon. Point well-taken. I'll stick with my (12-25)t cassette. I just wish there is a way I can finagle a higher range of gears with my 39t mid-ring and some of the back clusters.

Regards,

Try using the big ring. That's what it's for.

Well, if you had taken the time to read my original post carefully, you would have seen my mentioning the fact that "I am a little past half-way" in recovering from a broken femur.

I do like the big ring, and look forward to the day I can really crank that 52t monster, but for now, I've got to make do with my 39t ring most of the time. I was just hoping for a little more taller gears from a "possible" cassette range that could work in combination with my 39t ring in giving me slightly more challenging rides.

Regards,

This doesn't make any sense. A bigger gear is a bigger gear. Your femur can't tell if it's the big ring/bigger cog or middle ring/smaller cog.

Not sure exactly what you're trying to do, but it sounds to me as if all you need is a bigger middle ring, maybe the ubiquitous 42 tooth size? For optimal shifting you would want a different (so-called "9-speed") front derailer. Try your existing one first though, it will probably work well enough.

Sheldon "Life, The Universe And Everything" Brown

I currently find the 52t ring hard, and the 39t ring not challenging enough. I was actually looking for a 42t ring to replace the 39t with, but alas, I can't find a 10-Speed, 42t, Shimano Ultegra ring.

The next best thing is thus to see if I can find a Shimano 10-Speed cassette that can give me gears that are a bit taller than what I currently get at 39 x (12-25). But it looks like I am out of luck.

I can assure you that my femur certainly likes the 39t ring at present very very much. I can spin forever in 39 x 15 at present.

A 42 x 15 would be nice, not to talk of being more challenging, hence my original search for a 42t, 10-Speed ring.

Regards,

Ummm, get a clue: http://www.sheldonbrown.com/gears/

Shift into your big ring and 19t cog on back. That's an even smaller gear than 42x15. You can thank me later.

+1

There's no need for it to be a Shimano ring, any 130 ring designed for the middle position will work with your crank. In addition to Shimano, we carry the excellent TA rings from France.

The stuff about chainrings being "n-speed" specific is basically marketing hype. Pay no attention to such designations.

Sheldon "130" Brown