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View Full Version : Changing cassette and chain as same time? Cassette low gear vs cage length



bluerider
01-10-2013, 09:27 AM
So I am preparing for my winter maintenance on my cross bike. New cables, etc, etc. I did some checking on my chain and its has stretched to the point it should be replaced soon. So I was going to order a new chain. My question: do you usually want to replace the cassette at the same time as the chain. This is a SRAM setup on a cross bike that is a year old with approximately 2,000 miles. I need to look on the cassette more closely to look for wear but in general should you change them both at the same time? If so, I am considering a slight gear change. Right now, its a SRAM Apex 48-34 front and 12-26 rear with a Apex short cage derailleur. I have a SRAM Force short cage derailleur I am going to upgrade to. My question: can I go from a 12-26 cassette to 12-28 without trouble from the derailleur? I am just looking for a little extra bottom end and if I am going to change the cassette anyway, why not.

Thanks.

TwoWheelsDC
01-10-2013, 09:59 AM
I don't know about SRAM, but with Shimano my understanding is that as long as you are keeping the same number of cogs, you don't need to do any adjustments. I just swapped out my 12-30 Tiagra cassette for an 11-28 105 cassette and didn't have to do any derailleur adjustments...shifts smoothly with no issues. Changing the chain and cassette together is a loose rule of thumb, and 2k seems like enough miles to possibly warrant a change, but there are so many variables it's probably impossible to say for sure without checking the cassette itself.

thecyclingeconomist
01-10-2013, 09:59 AM
Sent you a PM... If you go to Perfomance bike, you should be able to pick up the parts for cheap (and they'll probably have them in stock)... or call your LBS and see if they have the parts in stock and pick them up before coming over.

Depending upon your cleaning schedule, (and based upon your chain, I'd say that you've been following a commuter's cleaning schedule: wipedowns/cleaning once a month-ish?)... I'd just replace the cassette, chain, and the two chainrings. That way everything will mesh perfectly and your shifting won't be compromised.

We can do all the mods on Saturday.

thecyclingeconomist
01-10-2013, 10:04 AM
I don't know about SRAM, but with Shimano my understanding is that as long as you are keeping the same number of cogs, you don't need to do any adjustments. I just swapped out my 12-30 Tiagra cassette for an 11-28 105 cassette and didn't have to do any derailleur adjustments...shifts smoothly with no issues. Changing the chain and cassette together is a loose rule of thumb, and 2k seems like enough miles to possibly warrant a change, but there are so many variables it's probably impossible to say for sure without checking the cassette itself.

Sorry, but for Bluerider's question, it's the gear-inches that determine whether a derailleur can soak up the extra chain, as well as provide enough chain for the "big-big" combo. It's not the number of cogs. Shifting won't be affected, but chain-length will be, and if your derailleur doesn't have a long enough cage, then you could do catastrophic damage (broken rear derailleur and chain, and possible a crash too) due to the drive train locking up... yes, I've had a customer have this happen after he home-modded his setup without knowing how to properly determine chain-length and his short-cage derailleur couldn't hand his new mega-range cassette).

I don't think he was asking about the horizontal shifting accuracy of the derailleur.

Just my take on it...

Safe riding and God bless!

mstone
01-10-2013, 10:13 AM
The specs on the derailleur should specify the gear range (both min/max on the rear as well as the total capacity on the front). Going to a smaller rear cog is generally fine, but there's usually an upper limit on how big they can get. It shouldn't be necessary to change out the whole drive train at 2k miles unless it's unusually worn (in which case, up your maintenance routine).

bluerider
01-10-2013, 10:47 AM
I will attempt to reply to multiple posts. My question was really too parts. 1.) do you change chain and cassette together as a general rule? 2.) If I change cassettes will going from 12-26 to 12-28 work with a short cage SRAM Force derailleur?


The specs on the derailleur should specify the gear range (both min/max on the rear as well as the total capacity on the front). Going to a smaller rear cog is generally fine, but there's usually an upper limit on how big they can get. It shouldn't be necessary to change out the whole drive train at 2k miles unless it's unusually worn (in which case, up your maintenance routine).

My maintenance routine is pretty good. I have the Park Tool chain washer I use every 300 miles or so (more if ridden in the rain and crap). I apply lube regularly. That being said, I have done a lot of rain riding this year including a Century entirely in the rain. Note: the chain is within the range to be replaced, its not horrid yet but its winter time bike maintenance season and I want to do everything I need to do. Since I am somewhat new at doing this, TheCyclingEconomist is going to help do it and teach me the finer points.


Sorry, but for Bluerider's question, it's the gear-inches that determine whether a derailleur can soak up the extra chain, as well as provide enough chain for the "big-big" combo. It's not the number of cogs. Shifting won't be affected, but chain-length will be, and if your derailleur doesn't have a long enough cage, then you could do catastrophic damage (broken rear derailleur and chain, and possible a crash too) due to the drive train locking up... yes, I've had a customer have this happen after he home-modded his setup without knowing how to properly determine chain-length and his short-cage derailleur couldn't hand his new mega-range cassette).

I don't think he was asking about the horizontal shifting accuracy of the derailleur.

Just my take on it...

Safe riding and God bless!

thecyclingeconomist is right on target. My question is about chain length which isn't a big deal when adding a new chain assuming you set the length correctly. My question was more about cassette sizes vs derailleur cage length. I know I can't run a 12-34 cassette with the short cage derailleur, you need SRAMs WiLi setup to do that. But going from 12-26 to 12-28 is a minor jump. I just didn't want to make the change and experience binding, poor shifting, etc because the 12-28 cassette and Force short cage derailleur weren't compatible with each other. I has since dug deep into the bowls of SRAM website and found that I can run this setup.

consularrider
01-10-2013, 03:02 PM
My experience with SRAM is the Rival line. I have used an 11-25, 11-26, and an 11-28 with the standard Rival rear derailleur. When I wanted to switch to an 11-30, I had to change to the WiFLi version with a longer cage.