Replacing cassette, will this cascade to changing a lot more?!?!

[tanggoman]

Originally posted by boudreaux
Every method of determining chain length is availabe at www.parktool.com in the repair and maintenance section, including the long and short versions of the formula. It's a good site to be familiar with.

Thanks to everyone for the replies, its this kind of brainstorming that we learn a lot from... Anyways, I got the cassette, installed it and haven't found any irregularities... the only thing I noticed is when the chain is on both the largest cog and ring, I can tell that the chain is very tight ang the rear derailler is really stretched forward as what one of the poster mentioned... I have a new chain ready for installation, in case the need arises...

 

[boudreaux]

Originally posted by drewski ........... it appears that chain-length (according to shimano) wouldn't really change, if the original setup was done according to these directions.

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You are assuming alot.

 

[treebound]

Thanks for the input boudreaux. I've got one bike with the brake shifters that I haven't had to do any adjustments with yet so my understanding mostly comes from the friction shifter on the downtube days. The arm lenght comment was in consideration of having enough wrap to take of chain slack. I'm off to read the links posted by brewski (thanks to you too) since I'll be setting up the race bike for wheel swaps in the spring.

 

[treebound]

Originally posted by boudreaux
WHY???

I thought the Ultegra max'd out at a 25 tooth cog, didn't know it could handle a 27, that's all. Maybe the shop that set up my bike likes to leave a little room or margin for error or something?
Oh well, back to reading and learning and lifting myself out of the dinosaur ages.

 

[el Ingles]

Shimano say max 27 but you can usually get away with 28 , as the chain is set on the large ring , small cog that sould not be a problem so just don´t use large ring three largest cogs / small ring three smallest cogs as this will wear out the chainrings and the chain prematurely . If in doudt check out www.sheldonbrown.com , ¿ do you really need a 12 ? if you don´t and would prefer a 13 then buy the 105 cassette ( HG70 ) 13 - 25 remove the 16 and add a 28 , my mechanic did that for me and it works fine and if you want to later you can go back to the 13 - 25 in about 10 mins ( including cleaning sprokets and washing hands ) or remove the 23 and 25 and replace with a 24 and a 28 , this I haven´t tried but the Spanish cycle mag Ciclismo al Fondo has recomended this on several ocasions , downside only one : you may need to replace the rear mech tension spring a bit more frequently if you use the 28 a lot , but that should not be a problem in normal ( ? ) usage , good luck .

 

[boudreaux]

Originally posted by el Inglés
...buy the 105 cassette ( HG70 ) 13 - 25 remove the 16 .....

Remove the 16!! That is the sweetest cog ever. People die for it. Removing one destroys years of accumulated good bike karma.Shame,Shame.

 

[drewski]

Originally posted by boudreaux
You are assuming alot.

i assume nothing other than that he can shift to the large chainring and smallest cog and look at the position of the pulleys.

easy.

is that alot? i didn't think so.

 

[boudreaux]

Originally posted by drewski
i assume nothing other than that he can shift to the large chainring and smallest cog and look at the position of the pulleys.

easy.

is that alot? i didn't think so.

Actually not if he has the cassette installed. His original post said he was thinking about the cassette in question,and wondering about chain length.Given that senario,the only answer is to use the formula.

 

[drewski]

Originally posted by boudreaux
Actually not if he has the cassette installed. His original post said he was thinking about the cassette in question,and wondering about chain length.Given that senario,the only answer is to use the formula.

actually . . . positively, absolutely yes, this should work even without the new cassette in question.

you obviously didn't read the shimano link or what i wrote. unless, of course, shimano wants to leave themselves open to having too short chains seizing and causing accidents.

their (shimano's) formula is dependant on the smallest cog and largest chainring. from there the derailleur's capacity will come into play. their assumption is that you will be following the capacity guidelines for max cog & total teeth. since the new cassette in question is within these guidelines, shimano says there will be no problem.

an 11T vs 12T smallest cog will not impact this measurement significantly because it's just half a link. if the chain-length works for the 11T and the pulley's are at the perpendicular position, as shown in their service guide, they will be at that position (or minutely off) for the 12T cog as well.

of course, this will not give the "optimal" length for all cassettes since the length will be identical for virtually all cassettes, but it conservatively provides an easy to check measure to see if the chain is adequate.

 

[boudreaux]

Originally posted by drewski
actually . . . positively, absolutely yes, this should work even without the new cassette in question.

you obviously didn't read the shimano link or what i wrote. unless, of course, shimano wants to leave themselves open to having too short chains seizing and causing accidents.

t

Shimano did not build the bike or size the chain that is on it. Granted though that is a way to determine adequate chain length for most cases. Another, is to use the small/small combination and if the chain is just shy of deagging on the RD cage,length should be adequate for the cogs that derailer can handle. It's all at www.parktool.com and it pays to check the big big 'just in case'.

 

[notryt]

Just curious... anyone jump in.. Ive raced...then just rode for the last 30 years.... Ive yet to understand why anyone would go from a 11-12 cog. unless youve just given up on going "Flat out" .. Dont understand really the point of a 27 either since the ultega has a 39 front.. at that ratio 27/39 you almost cant pedal fast enough to keep the bike upright... never mind the triple setup.. which i thought to be no more than a marketing gimmic anyway. Im not being sarcastic (well maybe a little) but i have never read anything that explained the reasoning for such setups. my most agressive setup is a 42-23.
my friend uses a 42-25 setup which i find way to be a very very light setup for climbing but within reason.

 

[boudreaux]

Just curious... anyone jump in.. Ive raced...then just rode for the last 30 years.... Ive yet to understand why anyone would go from a 11-12 cog. unless youve just given up on going "Flat out" .. Dont understand really the point of a 27 either since the ultega has a 39 front.. at that ratio 27/39 you almost cant pedal fast enough to keep the bike upright... never mind the triple setup.. which i thought to be no more than a marketing gimmic anyway. Im not being sarcastic (well maybe a little) but i have never read anything that explained the reasoning for such setups. my most agressive setup is a 42-23.
my friend uses a 42-25 setup which i find way to be a very very light setup for climbing but within reason.

It's all about strength and abilility and where you ride. I'm sure "real men" would not be caught dead on anything but a 53/42 and 11x21, even in the rockies at 10,000'.... LOL

 

[Randybaker99]

Ive yet to understand why anyone would go from a 11-12 cog.

Let's see, rider fitness level, rider weight, grade of road, very strong winds, bike setup and bike weight all come to mind.

 

[drewski]

Just curious... anyone jump in.. Ive raced...then just rode for the last 30 years.... Ive yet to understand why anyone would go from a 11-12 cog. unless youve just given up on going "Flat out" .. Dont understand really the point of a 27 either since the ultega has a 39 front.. at that ratio 27/39 you almost cant pedal fast enough to keep the bike upright... never mind the triple setup.. which i thought to be no more than a marketing gimmic anyway. Im not being sarcastic (well maybe a little) but i have never read anything that explained the reasoning for such setups. my most agressive setup is a 42-23.
my friend uses a 42-25 setup which i find way to be a very very light setup for climbing but within reason.

are you Memphman in disguise? sorry, it's just was what popped to mind . . .

 

[notryt]

I was in a hurry last time my friend has a 39-25 low end.. it is very light.. I am over 200 myself. and like the 52/11 i never used a 23 cog till last year.. (found the hills got mysteriously steeper over those winter months.) When i switched to the ultegra hg setup with the 39 low CR I have only used the 39/23 combination once in high winds... where anyone else in there right mind would have gotten off and walked.. must be that "Real Man" syndrome still talking to this 50 yr old body LOL. Pedal on.

 

[boudreaux]

I was in a hurry last time my friend has a 39-25 low end.. it is very light.. I am over 200 myself. and like the 52/11 i never used a 23 cog till last year.. (found the hills got mysteriously steeper over those winter months.) When i switched to the ultegra hg setup with the 39 low CR I have only used the 39/23 combination once in high winds... where anyone else in there right mind would have gotten off and walked.. must be that "Real Man" syndrome still talking to this 50 yr old body LOL. Pedal on.

I bet ya eat lots of spinach too..........