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Shimano 105 rear derailleur weird specs
"Rick Onanian" wrote in message
news I'm looking at Shimano's website, considering a triple crankset for my 2001 Giant TCR2, stock all 105 double. I'm trying to figure out how little I can get away with changing to put a triple on here. I can see that I'll need [obviously] a crankset and a front derailleur, but I wonder if I can get away with no new rear derailleur. How about, instead of a triple, compatibility with a mountain bike rear derailleur and then I use a really wide ratio cassette? I'd rather have the triple, but are Shimano road shifters compatible with Shimano MTB rear derailleurs? I think I don't understand a few terms. Here's what the site says about 105 double and triple rear derailleurs: Rear derailleur for double cranksets: Total Capacity: 37t Front Difference: 22t Rear derailleur for triple cranksets: Total Capacity: 29t Front Difference: 14t Maybe I don't understand the terminology, but I figured that the capacity is the amount of chain slack that the derailleur can take up, and the front difference is the largest difference in chainring that the rear derailleur can swallow suddenly (though I'm sure I'm wrong about that, I think I'm right about capacity). Rick - read the 'oracle' - Sheldon Brown's site at http://www.sheldonbrown.com/harris/index.html The glossary and articles will provide all the information you're looking for.... You can use a double RDR with a triple crank, but depending on how you size the chain you could have some slack when using the smallest ring and some of the smaller rear sprockets, or a nasty experience when you inadvertently try to use the largest ring and the largest sprocket if the chain is too short. Probably better to get a triple RDR. An alternative to a triple is to use a 'wider' cassette and/or smaller chainrings. The largest rear sprocket for most 'road' dérailleurs according to the Shimano spec is 27T, but lots of people report using 30 or even 32 - the disadvantage is bigger gaps between adjacent sprockets. The smallest chainring you can use on a 130mm BCD crank like the Shimano 105 is 38T, so to go smaller you'll need a new double crank with a smaller BCD. |
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Shimano 105 rear derailleur weird specs
Rick Onanian wrote:
I think I don't understand a few terms. Here's what the site says about 105 double and triple rear derailleurs: ... If you download the service instruction in pdf on the same page, you'll see that it all makes sense. The web page erroneously swapped the numbers between SS and GS. |
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Shimano 105 rear derailleur weird specs
On Sat, 09 Aug 2003 18:09:24 -0400, G Huang
wrote: see that it all makes sense. The web page erroneously swapped the numbers between SS and GS. I was afraid that was the case. -- Rick Onanian |
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Shimano 105 rear derailleur weird specs
Triple crank & BB, triple front der.... You will also need a new left
brifter to shift the triple. If a wider cluster might fit your needs you can use a 12-27 with the stock 105, and maybe up to a 30. Or just switch the rear derailer to a MTBike (XT or LX or ...) and use a 12-34. That's what I do with my Dura-Ace setup when I want to tour with some extra baggage. I use a 12-34 w/ a 50-38, and only switch the rear derailer. The 12-34 has very even ratios of 10 to 15%. 12-14-16-18-20-23-26-30-34 15.4% = ln(14/12) 13.4% 11.4% 10.5% 14.0% 12.3% 14.3% 12.5% -Bruce "Rick Onanian" wrote in message news I'm looking at Shimano's website, considering a triple crankset for my 2001 Giant TCR2, stock all 105 double. I'm trying to figure out how little I can get away with changing to put a triple on here. I can see that I'll need [obviously] a crankset and a front derailleur, but I wonder if I can get away with no new rear derailleur. How about, instead of a triple, compatibility with a mountain bike rear derailleur and then I use a really wide ratio cassette? I'd rather have the triple, but are Shimano road shifters compatible with Shimano MTB rear derailleurs? I think I don't understand a few terms. Here's what the site says about 105 double and triple rear derailleurs: Rear derailleur for double cranksets: Total Capacity: 37t Front Difference: 22t Rear derailleur for triple cranksets: Total Capacity: 29t Front Difference: 14t Maybe I don't understand the terminology, but I figured that the capacity is the amount of chain slack that the derailleur can take up, and the front difference is the largest difference in chainring that the rear derailleur can swallow suddenly (though I'm sure I'm wrong about that, I think I'm right about capacity). Everything else is the same (except the one for triples weighs a few more grams). Info from: http://bike.shimano.com/Road/105/com...umber=RD-5501- SS-S http://bike.shimano.com/Road/105/com...umber=RD-5501- GS-S Or, in tiny URLs: Double -- http://tinyurl.com/jilr Triple -- http://tinyurl.com/jilp -- Rick Onanian |
#5
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Shimano 105 rear derailleur weird specs
bruce- Triple crank & BB, triple front der.... You will also need a new left
brifter to shift the triple. BRBR If the setup is 9s...the left shifter is double and triple compatible..think in 2001 it was... Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302 (303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene" |
#6
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Shimano 105 rear derailleur weird specs
On Sat, 9 Aug 2003 17:06:15 -0500, Grenouil
wrote: Rick - read the 'oracle' - Sheldon Brown's site at http://www.sheldonbrown.com/harris/index.html Of course...I never thought to look there for routine info, just the wacky stuff! You can use a double RDR with a triple crank, but depending on how you size the chain you could have some slack when using the smallest ring and some of the smaller rear sprockets, or a nasty experience when you inadvertently try to use the largest ring and the largest sprocket if the chain is too short. Probably better to get a triple RDR. I think I can shift carefully. Do I dare find out? An alternative to a triple is to use a 'wider' cassette and/or smaller chainrings. The largest rear sprocket for most 'road' dérailleurs according to the Shimano spec is 27T, but lots of people report using 30 or even 32 - the disadvantage is bigger gaps between adjacent sprockets. I can handle the wide ratios. I don't need 9 gears all a single tooth (or two) apart from eachother. The smallest chainring you can use on a 130mm BCD crank like the Shimano 105 is 38T, so to go smaller you'll need a new double crank with a smaller BCD. Hmm...I could put a wider cassette and a new double crankset with a smaller small ring...that may be an option. -- Rick Onanian |
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