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Old 10-11-12, 08:50 AM   #26
Barrettscv 
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Originally Posted by Retro Grouch View Post
I think that's bad advice.

A chain that's too short to safely cover the big/big combination can cause a LOT of damage to your bike in the blink of an eyelash. One that's too long to cover the little/little will only make annoying noise.

Besides, I have never used my granny chainring with any but my largest 2 or 3 rear cogs. I can easily picture myself accidentally shifting into the big/big, but I can't imagine ever accidentally shifting into the little/little.
I don't base my opinions on guesswork. The actual chain wrap capacity of a Shimano triple road derailleur is far greater than you think. A correctly sized chain can allow the use of every combination with a 52,39, & 26 chainring set and a 12-27 cassette.

Below is a 50, 39 & 26t triple with a 12-30 ten speed cassette. I can safely use every gear combination. I do avoid the small-small combination in practice, but the drivetrain will allow that combination without an issue.

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Last edited by Barrettscv; 10-11-12 at 09:02 AM.
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Old 10-11-12, 09:34 AM   #27
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Originally Posted by rdtompki View Post
Sweet looking setup!. I'll be interested to see how well the FSA triple shifts. I don't have indexed shifting up front so the shift efficiency has a big operator component.
You should be happy! My FSA triple shifts fine. I use non-indexed Campy brifters, with Shimano front & rear derailleurs, a 50-39-24, and 13-25 out back. Everything works nice.
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Old 10-11-12, 10:15 AM   #28
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Sweet looking setup!. I'll be interested to see how well the FSA triple shifts. I don't have indexed shifting up front so the shift efficiency has a big operator component.
Thanks! Will you be swapping out your FD as well for a triple variety or sticking with the double? That may have more to do with shift efficiency than anything else.
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Old 10-11-12, 10:30 AM   #29
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I don't base my opinions on guesswork. The actual chain wrap capacity of a Shimano triple road derailleur is far greater than you think. A correctly sized chain can allow the use of every combination with a 52,39, & 26 chainring set and a 12-27 cassette.
Yeah, but you didn't tell all that to the OP so it was still bad advice.

Also, an Ultegra long arm rear derailleur is rated for 38t of wrap up. 52-26 for the crank = 26. 27-12 for the cassette = 15. 26 + 15 = 41. Not only am I not guessing but I've also shown my work.

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Old 10-11-12, 10:50 AM   #30
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Yeah, but you didn't tell all that to the OP so it was still bad advice.

Also, an Ultegra long arm rear derailleur is rated for 38t of wrap up. 52-26 for the crank = 26. 27-12 for the cassette = 15. 26 + 15 = 41. Not only am I not guessing but I've also shown my work.
Retro,

I've been following this thread because I've been thinking that I'll 'need' a triple on N+1 (I'm just still pretty weak on the bigger hills).
Can you expand on this for a newbie? Specifically, how do you get the '15' number for the cassette? And does 41 > 38 mean that it 'may not work'
or 'really won't work'?

I'd be interested in knowing if something like a 50/39/28, 30-12 would work (or even 50/39/26 32-12)
thanks...
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Old 10-11-12, 11:23 AM   #31
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Yeah, but you didn't tell all that to the OP so it was still bad advice.

Also, an Ultegra long arm rear derailleur is rated for 38t of wrap up. 52-26 for the crank = 26. 27-12 for the cassette = 15. 26 + 15 = 41. Not only am I not guessing but I've also shown my work.
I'm sure you could argue this for a long time. Did you know that the factory rating has a safety factor? If you have the skill, you can inspect your equipment and exceed the factory specifications.
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Old 10-11-12, 11:30 AM   #32
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I'd be interested in knowing if something like a 50/39/28, 30-12 would work (or even 50/39/26 32-12)
thanks...
A 50, 39 & 26 and a 12-30 cassette will work on every gear combination with 105 or Ultegra rear derailleurs for triple. However, the chain length becomes critical. The rear derailleur must have some remaining range of motion when adjusted to the large cog and large chainring combination. The chain must be long enough on the large-large combination without being so long that the chain goes slack while on the small cog and small chainring combination. The chain wrap capacity of the drivetrain is sufficient, if installed by a skilled mechanic.

A 50, 39 & 26 and a 12-32 cassette will not work well on every gear combination. You will need to use a Deore rear derailleur. Pictured below is a 50, 39 & 26 and a 11-32 cassette;

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Old 10-11-12, 11:54 AM   #33
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Retro,

I've been following this thread because I've been thinking that I'll 'need' a triple on N+1 (I'm just still pretty weak on the bigger hills).
Can you expand on this for a newbie? Specifically, how do you get the '15' number for the cassette? And does 41 > 38 mean that it 'may not work'
or 'really won't work'?

I'd be interested in knowing if something like a 50/39/28, 30-12 would work (or even 50/39/26 32-12)
thanks...
15 is 27 (biggest cog) minus 12 (smallest cog).

The chain has to be long enough to safely cover the big/big combination. If it's too short, and you accidentally shift into that combination, the easiest thing is to bend the rear derailleur into your spokes. That can be real expensive and that's the only reason why I made a point of it.

For a customer bike, once the chain is long enough, I make sure the rear derailleur is able to take up all of the chain slack when in the little/little combination. For a personal bike I might "cheat" a little on that since I only use the granny chainring with the biggest 2 or 3 rear cogs. In other words, even though 41 > 38, the combination will almost surely work but I wouldn't send a customer bike out that way.
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Old 10-11-12, 12:05 PM   #34
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Originally Posted by Esteban58 View Post
Retro,

I've been following this thread because I've been thinking that I'll 'need' a triple on N+1 (I'm just still pretty weak on the bigger hills).
Can you expand on this for a newbie? Specifically, how do you get the '15' number for the cassette? And does 41 > 38 mean that it 'may not work'
or 'really won't work'?

I'd be interested in knowing if something like a 50/39/28, 30-12 would work (or even 50/39/26 32-12)
thanks...
Esteban58,
To expand on Retro's post, the formula for chain "wrap" or derailleur "capacity" is (biggest chainring - smallest chainring) + (biggest cog - smallest cog). So in your first example, (50-28) + (30-12) = 40t of capacity or wrap that the rear derailleur should accommodate. Shimano cites this spec to ensure that clueless cyclists don't get into trouble when they find themselves in the big-big or small-small gear combinations (aka cross-chaining). No competent cyclist uses these gear combos anyway so this spec is often "pushed" by those of us who like to tinker and know what gear combinations to avoid. For example, my RD is spec'ed for only 37t but my gear setup officially dictates an RD that can wrap 40t. I have no problems because I size the chain for the big-big combo and do not ride in the small-small combo where there is marginally too much slack in the chain. It is FAR better to have too much chain slack than not enough.

This is a good read on Sheldon's site: http://sheldonbrown.com/deakins/lowgears.html
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Old 10-11-12, 12:13 PM   #35
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ok, so 50/39/28, 28-12 or maybe 50/39/30 28-12 may be more prudent choices (I *mostly) ride small/big-3 -> middle/all -> bit/small-3 but shifting
the derailleur into the rear wheel is something I could see myself doing when gassed on a hill and picking the wrong time to have a senior moment.

thanks!

Or I guess I can just HTFU and get a compact. 50/34 - 12/30 is pretty standard.
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Old 10-11-12, 12:25 PM   #36
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15 is 27 (biggest cog) minus 12 (smallest cog).

The chain has to be long enough to safely cover the big/big combination. If it's too short, and you accidentally shift into that combination, the easiest thing is to bend the rear derailleur into your spokes. That can be real expensive and that's the only reason why I made a point of it.

For a customer bike, once the chain is long enough, I make sure the rear derailleur is able to take up all of the chain slack when in the little/little combination.
And that would be prudent and conservative but not a practical necessity.

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Originally Posted by Retro Grouch View Post
For a personal bike I might "cheat" a little on that since I only use the granny chainring with the biggest 2 or 3 rear cogs. In other words, even though 41 > 38, the combination will almost surely work but I wouldn't send a customer bike out that way.
You should not have to "cheat" to get the result I recommend. Have you ever tried? Or do you just start a dispute anytime a result conflicts with your opinion?
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Old 10-11-12, 01:39 PM   #37
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Have you ever tried? Or do you just start a dispute anytime a result conflicts with your opinion?
Trust me, I've experimented with a lot of different drive train combinations over the years. Generally the only time that i initiate a dispute is when I think that somebody is recommending something irresponsible like shortening a chain without first making sure the big/big combination can be safely covered. Read your first post over. That's what you said.
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Old 10-11-12, 05:55 PM   #38
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Trust me, I've experimented with a lot of different drive train combinations over the years. Generally the only time that i initiate a dispute is when I think that somebody is recommending something irresponsible like shortening a chain without first making sure the big/big combination can be safely covered. Read your first post over. That's what you said.
Like I said, you can keep arguing. We all here can read.
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Old 10-11-12, 07:10 PM   #39
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Actually you can put a smaller inner chainring on new Ultegra triple cranks but you will need a new middle ring first. As you know, with the 6703 Ultegra triple, Shimano adopted the older Dura Ace triple design of mounting the inner ring directly onto the middle ring using a proprietary 92mm BCD for which only 30t rings are available. By replacing the stock Ultegra middle ring with a Specialites TA Alize K, you can mount a granny ring as low as 24t. The Alize K uses the industry-standard 74mm BCD for the granny - not the Shimano-only 92mm. It's not a cheap ring, but it is a TA after all. I got mine from Peter White Cycles - see this page. Here's is my Alize K setup:

[picture removed]

This is a DA FC-7703 crank (same 130/92 BCD as Ultegra) with the stock 53t big ring, a 39t Alize K and a 26t granny. With a 10 speed 12-28 cassette, I have a nice wide gear range (which my knees appreciate riding in the Berkshires here in western MA), fewer front shifts, and tight gear spacing (one tooth jumps from 12t to 17t). Triples are great!
Expensive, but nice information... thanks for posting that! It's another way to go and I may well look into it.
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Old 10-11-12, 07:26 PM   #40
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I refuse to embarrass myself by walking up a hill! On the other hand, I have no problem embarrassing myself by using my 26-32 combo riding up a hill.
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Old 10-11-12, 08:00 PM   #41
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There is a lot of talk about ratios etc, but no one has mentioned your shifters. Depending on what you are have now you may have to change the left shift lever to accommodate a triple.
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Old 10-11-12, 08:04 PM   #42
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There is a lot of talk about ratios etc, but no one has mentioned your shifters. Depending on what you are have now you may have to change the left shift lever to accommodate a triple.
I have Campy Chorus 10-spd shifters, same as our tandem. The left shifter has 12 "clicks" and shifts the quad chainrings on our daVinci without problem. I'm pretty confident it will work on a triple chainring.
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Old 10-11-12, 08:28 PM   #43
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The die is cast, orders have been placed. I'm switching my Volagi FSA SL-K light Compact Crankset over to a triple. Found the same Crankset in a triple overseas as they are not sold in the US. Why do you ask? Well, it's not to get lower gears necessarily. I'm running an 11-32 cassette now and the 34-32 will get me up almost anything one time, like the 2500' climb 2 miles from my house. While on our tandem I'm resigned to the big jumps in our 11-32 (or 11-36), I find the jumps on my single interfere with the karma.

I'm going with a 12-27 cassette for regular, non-killer rides as the 30-27 will only be a few percentage points higher than what I had before and I really am going to like having the 16t cog. For longer and/or tougher stuff I figure a 36t cog will do the trick. If I can't get up a hill in 30-36 then I have no business riding that hill.

My 84 Miyata 912 had a triple and I don't recall way back then wishing I had something different. My son still uses that bike as his beater, but I'm getting it back soon. He's made some changes, but hasn't changed out the crankset thank goodness so I'll have two triples in my stable, N+1 so to speak.

My biggest concern is that with a triple I won't be allowed to post in the 41, but I'm figuring I'll still be ok here and in the C/A forum.
Do you have to change out the shifters as well (from a compact double to triple)? I have Shimano brifters with my CD (Ultegra) and considered going to a triple.
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Old 10-11-12, 09:05 PM   #44
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Do you have to change out the shifters as well (from a compact double to triple)? I have Shimano brifters with my CD (Ultegra) and considered going to a triple.
I have to change the FD of course, but the Campy shifters will handle a triple. The left shifter is not really "indexed", it pulls a good deal of cable over a total of 12 clicks, so it has plenty of resolution for a triple. Should be a good setup. On my double I only use part of the travel of the shifter.

I think the Shimano left brifter is double/triple specific. There were versions that were designed to handle both, but I believe Shimano moved in a different direction.
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Old 10-11-12, 09:12 PM   #45
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...I think the Shimano left brifter is double/triple specific...
This is correct for the Ultegra 6700 group. Don't know about others.
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Old 10-12-12, 12:25 AM   #46
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Enough has been said about the number of teeth that Dérailleurs can handle but when I set up the bike with an 11/28 and 52/40/26 for the mountains I had a problem. Set it up for Big/Big and with the shortest chain possible and when I went 26/28 I had a problem. The top RD cog was rubbing on the cassette. Tried to set the screw to tension the chain away but had to go 28 on the granny to get it acceptable. This was with a Sora RD and there is a limit to how many teeth the RD can handle. It was still too close for comfort though

Finally set the Chain length too short for big/big but I reckoned that for mountains I would not be using the 52 in any case so it would not have been a problem. It wasn't till I got back to the UK and loaned the bike out and I then had to give a lesson to the "NEW" rider on how to utilise the gears

And also had a problem on the Pinnie that had 50/34-11/25 fitted when I put on the 12/30 cassette. Chain length was perfect but I had to adjust the Tiagra RD away from the cassette to stop the grinding noise of the cogs touching.
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Old 10-12-12, 07:04 AM   #47
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Do you have to change out the shifters as well (from a compact double to triple)? I have Shimano brifters with my CD (Ultegra) and considered going to a triple.
How many cogs do you have on the back?

For 9-speed stuff, Shimano actually uses the same part number for doubles and triples. I techincally own (the bikes live at my sons' houses) a double crankset road bike and a triple crankset tandem that use identical Ultegra shifters. As a double I get 2 shift positions for each chainring. As a triple I get 1 position for the granny, 2 for the middle ring and 1 shift position for the big ring. Both bikes have flight Deck computers and both always indicate the appropriat chainring so I'm pretty sure they are set up the way that Shimano intended.
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Old 10-12-12, 07:05 AM   #48
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... Set it up for Big/Big and with the shortest chain possible and when I went 26/28 I had a problem. The top RD cog was rubbing on the cassette. Tried to set the screw to tension the chain away but had to go 28 on the granny to get it acceptable. This was with a Sora RD and there is a limit to how many teeth the RD can handle. It was still too close for comfort though....
Hmmm, I'm having a little trouble understanding this. You're talking about the B screw adjustment, right? You fixed the RD jockey wheel rubbing on the biggest cog of the cassette by changing the granny ring? I seem to be missing something (likely).
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Old 10-12-12, 08:28 AM   #49
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Originally Posted by pexio View Post
Hmmm, I'm having a little trouble understanding this. You're talking about the B screw adjustment, right? You fixed the RD jockey wheel rubbing on the biggest cog of the cassette by changing the granny ring? I seem to be missing something (likely).
Sometimes a too long chain will cause that. He fixed it by substituting a little bigger granny ring which took up an additional link of chain slack and ultimately by "cheating" a little on chain length for his big/big combination.

I wonder if he could have fixed it by substituting a longer B screw to pull his derailleur a bit farther back or by even reversing the B screw in his derailleur.
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Old 10-12-12, 08:39 AM   #50
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Quote:
Originally Posted by Retro Grouch View Post
Sometimes a too long chain will cause that. He fixed it by substituting a little bigger granny ring which took up an additional link of chain slack and ultimately by "cheating" a little on chain length for his big/big combination.

I wonder if he could have fixed it by substituting a longer B screw to pull his derailleur a bit farther back or by even reversing the B screw in his derailleur.
Maybe, but he said, "Set it up for Big/Big and with the shortest chain possible and when I went 26/28 I had a problem." So was the 11-28 cassette new too, in addition to the smaller granny? I wonder if, with the shortened chain, in the big/big combo, the RD was pulled too far forward causing the rub? Still don't get how the bigger granny fixed the problem. For sure, a longer B screw or flipping it backwards might have helped.
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