Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

Chain length for dummies

Notices
Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

Chain length for dummies

Old 07-22-22, 07:32 AM
  #26  
smd4
Senior Member
 
Join Date: Dec 2020
Location: Wake Forest, NC
Posts: 2,472

Bikes: 1989 Cinelli Supercorsa

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 1488 Post(s)
Liked 1,114 Times in 710 Posts
Originally Posted by cyccommute View Post
I prefer the Park Tool method which is to use 2 rivets. It’s less ambiguous. Picture stolen from that article
That's not helpful. Someone could count two rivets from the same side plate.

I'm not sure why people have to make bikes the most complicated machines on the planet. They aren't.

Bike chains aren't rocket science. One link, two links, half links, two half-links, full link, the "Park method"...Really? Unless you're using a quick link, just make sure the wide end fits on the narrow end. Put a rivet through and call it a day.
smd4 is offline  
Old 07-22-22, 08:37 AM
  #27  
cyccommute 
Mad bike riding scientist
 
cyccommute's Avatar
 
Join Date: Nov 2004
Location: Denver, CO
Posts: 25,833

Bikes: Some silver ones, a red one, a black and orange one, and a few titanium ones

Mentioned: 138 Post(s)
Tagged: 1 Thread(s)
Quoted: 5232 Post(s)
Liked 2,791 Times in 1,647 Posts
Originally Posted by smd4 View Post
That's not helpful. Someone could count two rivets from the same side plate.
Huh? I’m not following what you are trying to say. The Park method (probably not original to them) is a whole lot less ambiguous than most other methods I’ve seen.

I'm not sure why people have to make bikes the most complicated machines on the planet. They aren't.
While I agree, you can go the other way and make things too simplistic.

Bike chains aren't rocket science. One link, two links, half links, two half-links, full link, the "Park method"...Really? Unless you're using a quick link, just make sure the wide end fits on the narrow end. Put a rivet through and call it a day.
Measuring out a new chain against an old chain is the easiest way to get the chain length right but some times you just can’t use that method. Changes in cassette or changes in chainring size or getting a bike without a chain can all mean that a new chain will have to be sized properly. Just “jamming the rivet” through could lead to a chain that is too long so that it flops around or too short so that it ends up damaging the drivetrain.

And modern chains should never have a rivet redriven. They aren’t designed for that anymore.
__________________
Stuart Black
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Days of Wineless Roads. Bed and Breakfasting along the KATY
Twisting Down the Alley. Misadventures in tornado alley.
cyccommute is offline  
Old 07-22-22, 08:46 AM
  #28  
smd4
Senior Member
 
Join Date: Dec 2020
Location: Wake Forest, NC
Posts: 2,472

Bikes: 1989 Cinelli Supercorsa

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 1488 Post(s)
Liked 1,114 Times in 710 Posts
Originally Posted by cyccommute View Post
Huh? I’m not following what you are trying to say.
I'm not sure how to simplify what I wrote.
smd4 is offline  
Old 07-22-22, 08:54 AM
  #29  
cyccommute 
Mad bike riding scientist
 
cyccommute's Avatar
 
Join Date: Nov 2004
Location: Denver, CO
Posts: 25,833

Bikes: Some silver ones, a red one, a black and orange one, and a few titanium ones

Mentioned: 138 Post(s)
Tagged: 1 Thread(s)
Quoted: 5232 Post(s)
Liked 2,791 Times in 1,647 Posts
Originally Posted by smd4 View Post
I'm not sure how to simplify what I wrote.
What do you mean “someone could count two rivets from the same side plate?” What is the “same side plate”? The picture I attached is fairly clear where you start to count from and where you end at. It even fits in your idea of keeping things simple. It’s a whole lot better than measuring the chainstay and doing a bunch of math with charts and derivatives and chainwheel angles.
__________________
Stuart Black
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Days of Wineless Roads. Bed and Breakfasting along the KATY
Twisting Down the Alley. Misadventures in tornado alley.
cyccommute is offline  
Old 07-22-22, 09:05 AM
  #30  
smd4
Senior Member
 
Join Date: Dec 2020
Location: Wake Forest, NC
Posts: 2,472

Bikes: 1989 Cinelli Supercorsa

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 1488 Post(s)
Liked 1,114 Times in 710 Posts
Originally Posted by cyccommute View Post
What do you mean “someone could count two rivets from the same side plate?” What is the “same side plate”? The picture I attached is fairly clear where you start to count from and where you end at. It even fits in your idea of keeping things simple.
If we have to get to the point when I have to define what a side plate is, then it's no longer simple.

Seems to me, when it comes to sizing a chain, it's intuitive to some, but akin to differential calculus to others. I guess I just have to accept that.

Originally Posted by cyccommute View Post
It’s a whole lot better than measuring the chainstay and doing a bunch of math with charts and derivatives and chainwheel angles.
Absolutely agree.
smd4 is offline  
Old 07-22-22, 09:25 AM
  #31  
cyccommute 
Mad bike riding scientist
 
cyccommute's Avatar
 
Join Date: Nov 2004
Location: Denver, CO
Posts: 25,833

Bikes: Some silver ones, a red one, a black and orange one, and a few titanium ones

Mentioned: 138 Post(s)
Tagged: 1 Thread(s)
Quoted: 5232 Post(s)
Liked 2,791 Times in 1,647 Posts
Originally Posted by smd4 View Post
If we have to get to the point when I have to define what a side plate is, then it's no longer simple.
You are putting the wrong emPHASis on the wrong sylLABle. The “side plate” isn’t the problem. The “same” connected with side plate is what I don’t understand. Again, the picture is clear where you start from and where you end. I find it very helpful, as do most people I explain it to during mechanic’s classes and while working in the shop.
__________________
Stuart Black
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Days of Wineless Roads. Bed and Breakfasting along the KATY
Twisting Down the Alley. Misadventures in tornado alley.
cyccommute is offline  
Old 07-22-22, 09:30 AM
  #32  
smd4
Senior Member
 
Join Date: Dec 2020
Location: Wake Forest, NC
Posts: 2,472

Bikes: 1989 Cinelli Supercorsa

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 1488 Post(s)
Liked 1,114 Times in 710 Posts
Originally Posted by cyccommute View Post
You are putting the wrong emPHASis on the wrong sylLABle. The “side plate” isn’t the problem. The “same” connected with side plate is what I don’t understand. Again, the picture is clear where you start from and where you end. I find it very helpful, as do most people I explain it to during mechanic’s classes and while working in the shop.
Hey, whatever works for you.

If I had to explain chains and how to count rivets from any particular staring point to any aspiring mechanics, they would no longer be aspiring mechanics in my shop.
smd4 is offline  
Old 07-22-22, 10:34 AM
  #33  
urbanknight
Over the hill
 
urbanknight's Avatar
 
Join Date: Mar 2006
Location: Los Angeles, CA
Posts: 23,746

Bikes: Giant Defy

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 687 Post(s)
Liked 749 Times in 450 Posts
It sounds like the point here is that a picture is worth a thousand words.
__________________
It's like riding a bicycle
urbanknight is offline  
Old 07-22-22, 11:37 AM
  #34  
cyccommute 
Mad bike riding scientist
 
cyccommute's Avatar
 
Join Date: Nov 2004
Location: Denver, CO
Posts: 25,833

Bikes: Some silver ones, a red one, a black and orange one, and a few titanium ones

Mentioned: 138 Post(s)
Tagged: 1 Thread(s)
Quoted: 5232 Post(s)
Liked 2,791 Times in 1,647 Posts
Originally Posted by urbanknight View Post
It sounds like the point here is that a picture is worth a thousand words.
Which doesn’t stop some people from requiring the 1000 word explanation of something rather simple to understand.
__________________
Stuart Black
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Days of Wineless Roads. Bed and Breakfasting along the KATY
Twisting Down the Alley. Misadventures in tornado alley.
cyccommute is offline  
Old 07-22-22, 11:40 AM
  #35  
cyccommute 
Mad bike riding scientist
 
cyccommute's Avatar
 
Join Date: Nov 2004
Location: Denver, CO
Posts: 25,833

Bikes: Some silver ones, a red one, a black and orange one, and a few titanium ones

Mentioned: 138 Post(s)
Tagged: 1 Thread(s)
Quoted: 5232 Post(s)
Liked 2,791 Times in 1,647 Posts
Originally Posted by smd4 View Post
Hey, whatever works for you.

If I had to explain chains and how to count rivets from any particular staring point to any aspiring mechanics, they would no longer be aspiring mechanics in my shop.
Jeeze you don’t think much of your aspiring mechanics, do you? How do you tell people how to determine a proper chain length?
__________________
Stuart Black
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Days of Wineless Roads. Bed and Breakfasting along the KATY
Twisting Down the Alley. Misadventures in tornado alley.
cyccommute is offline  
Old 07-22-22, 12:10 PM
  #36  
smd4
Senior Member
 
Join Date: Dec 2020
Location: Wake Forest, NC
Posts: 2,472

Bikes: 1989 Cinelli Supercorsa

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 1488 Post(s)
Liked 1,114 Times in 710 Posts
Originally Posted by cyccommute View Post
Jeeze you don’t think much of your aspiring mechanics, do you? How do you tell people how to determine a proper chain length?
Read the manual.
smd4 is offline  
Old 07-22-22, 04:49 PM
  #37  
cyccommute 
Mad bike riding scientist
 
cyccommute's Avatar
 
Join Date: Nov 2004
Location: Denver, CO
Posts: 25,833

Bikes: Some silver ones, a red one, a black and orange one, and a few titanium ones

Mentioned: 138 Post(s)
Tagged: 1 Thread(s)
Quoted: 5232 Post(s)
Liked 2,791 Times in 1,647 Posts
Originally Posted by smd4 View Post
Read the manual.
Hummm…Let’s see. I recall someone saying something. Oh, yeah here it is

Originally Posted by smd4 View Post
That's not helpful.
I can tell someone how to size a chain simply before they could even find the manual. It’s not that hard.

To paraphrase a (in)famous American saying: Those who can teach, teach. Those who can’t teach are grumpy old cusses who will tell you “learn for yourself”.
__________________
Stuart Black
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Days of Wineless Roads. Bed and Breakfasting along the KATY
Twisting Down the Alley. Misadventures in tornado alley.

Last edited by cyccommute; 07-22-22 at 04:54 PM.
cyccommute is offline  
Old 07-22-22, 05:07 PM
  #38  
smd4
Senior Member
 
Join Date: Dec 2020
Location: Wake Forest, NC
Posts: 2,472

Bikes: 1989 Cinelli Supercorsa

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 1488 Post(s)
Liked 1,114 Times in 710 Posts
If reading the manufacturer’s instructions on how to properly size a chain for a given derailleur is too difficult or time consuming, I’d tell that person to make the chain length short enough so that it doesn’t sag, and tensions the rear derailleur slightly in small rear/small front, but long enough to go around big/big without extending the RD cage to its limit.
smd4 is offline  
Old 07-22-22, 05:47 PM
  #39  
cyccommute 
Mad bike riding scientist
 
cyccommute's Avatar
 
Join Date: Nov 2004
Location: Denver, CO
Posts: 25,833

Bikes: Some silver ones, a red one, a black and orange one, and a few titanium ones

Mentioned: 138 Post(s)
Tagged: 1 Thread(s)
Quoted: 5232 Post(s)
Liked 2,791 Times in 1,647 Posts
Originally Posted by smd4 View Post
If reading the manufacturer’s instructions on how to properly size a chain for a given derailleur is too difficult or time consuming, I’d tell that person to make the chain length short enough so that it doesn’t sag, and tensions the rear derailleur slightly in small rear/small front, but long enough to go around big/big without extending the RD cage to its limit.
So “just guess”? You said that the two rivet method wasn’t helping but I fail to see how your above method is helping. The manual for Shimano says to put the chain on the big/big combination and add 2 links (the inner link is one link and the outer link is another). Or, functionally, it’s counting two rivets.

SRAM is a bit more complicated

Wrap the chain around the large chainring (for 2x and 3x systems) and largest cassette cog.
For full suspension bicycles, add one inner
link and one outer link where the chain starts to overlap. For hardtail bicycles, add two inner links and two outer links where the chain starts to overlap.
However their graphic shows the adding 4 rivet is for 1x systems. But, honestly, the two rivet method works just as well for SRAM chains for 2x and 3x with hardtails.
__________________
Stuart Black
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Days of Wineless Roads. Bed and Breakfasting along the KATY
Twisting Down the Alley. Misadventures in tornado alley.
cyccommute is offline  
Old 07-22-22, 05:55 PM
  #40  
smd4
Senior Member
 
Join Date: Dec 2020
Location: Wake Forest, NC
Posts: 2,472

Bikes: 1989 Cinelli Supercorsa

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 1488 Post(s)
Liked 1,114 Times in 710 Posts
Dude, what do you want? That’s not what the manual says for MY derailleur. ‘Cause THEY’RE DIFFERENT! So if you’re not going to use the manual for your particular RD, then my advice is NOT GUESS, but size the chain on the bike.

But go ahead: teach your “aspiring mechanics” to count links, run internet formulas, divide by the square of the root, use two small screwdrivers and any other methods you deem simple enough for your non-reading mechanics to comprehend. Geeze…
smd4 is offline  
Old 07-22-22, 11:58 PM
  #41  
cyccommute 
Mad bike riding scientist
 
cyccommute's Avatar
 
Join Date: Nov 2004
Location: Denver, CO
Posts: 25,833

Bikes: Some silver ones, a red one, a black and orange one, and a few titanium ones

Mentioned: 138 Post(s)
Tagged: 1 Thread(s)
Quoted: 5232 Post(s)
Liked 2,791 Times in 1,647 Posts
Originally Posted by smd4 View Post
Dude, what do you want? That’s not what the manual says for MY derailleur. ‘Cause THEY’RE DIFFERENT! So if you’re not going to use the manual for your particular RD, then my advice is NOT GUESS, but size the chain on the bike.
How are derailers DIFFERENT!? Shimano derailers for mountain and road use the same method of determining chain length. The two rivet or two link (or add an inch) methods work in the vast majority of cases. In fact, I haven’t seen sizing of the chain addressed in the derailer manual. It’s addressed in the chain manual and the suggestion is the simple one presented above.

I’m not the one guessing. I use a method that works for every bike I’ve ever installed a chain on…and I’ve worked on thousands of bicycles.

But go ahead: teach your “aspiring mechanics” to count links, run internet formulas, divide by the square of the root, use two small screwdrivers and any other methods you deem simple enough for your non-reading mechanics to comprehend. Geeze…
I’m not doing all that. Nor have I suggested anything that is complicated. You want something simple and effective. I agree. I can explain it to someone in less than 30 seconds. I can explain it in far fewer than 1000 words. And it is relatively easy to remember. My “aspiring mechanics” and I have better things to do than go look up everything every time there is a question. That’s a waste of their time and mine. As an instructor, I want to have people learn how to work on bikes but I’m not going to frustrate them by saying “go look it up, I’ve got better things to do”.
__________________
Stuart Black
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Days of Wineless Roads. Bed and Breakfasting along the KATY
Twisting Down the Alley. Misadventures in tornado alley.
cyccommute is offline  
Old 07-23-22, 03:48 AM
  #42  
alexk_il
Junior Member
Thread Starter
 
Join Date: Jun 2022
Posts: 188
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 118 Post(s)
Liked 28 Times in 20 Posts
Originally Posted by alexk_il View Post
Watched a few youtube videos explaining how to measure the correct chain link. Got it. Then found online chain length calculators. Makes sense too. But now I totally confused.

So, assuming I know my bike's chain stay...
  • Do I measure the length on my bike or do I simply set the number of links exactly as recommended by calculators
  • Also, this calculator sometimes comes up with odd number of links. Do I round up or down to make it even?
Thanks
Answering my own question after changing my cranks/chainrings.

The calculator gave me result that at is longer than what I need after measuring.

I guess the main reason is that chainstays specs for my bike are quoted for a larger frame size than what I am using. I had to shorten the chain by two links compared to the calculator.

My takeaways: measuring always works, calculator only works if correct specifications can be found or measured.
alexk_il is offline  
Old 07-23-22, 04:14 AM
  #43  
smd4
Senior Member
 
Join Date: Dec 2020
Location: Wake Forest, NC
Posts: 2,472

Bikes: 1989 Cinelli Supercorsa

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 1488 Post(s)
Liked 1,114 Times in 710 Posts
Originally Posted by cyccommute View Post
How are derailers DIFFERENT!?
If you read the manuals, you’d know.
smd4 is offline  
Old 07-23-22, 08:29 AM
  #44  
urbanknight
Over the hill
 
urbanknight's Avatar
 
Join Date: Mar 2006
Location: Los Angeles, CA
Posts: 23,746

Bikes: Giant Defy

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 687 Post(s)
Liked 749 Times in 450 Posts
Originally Posted by alexk_il View Post
Answering my own question after changing my cranks/chainrings.

The calculator gave me result that at is longer than what I need after measuring.

I guess the main reason is that chainstays specs for my bike are quoted for a larger frame size than what I am using. I had to shorten the chain by two links compared to the calculator.

My takeaways: measuring always works, calculator only works if correct specifications can be found or measured.
Better to have to go shorter than longer. Glad you got it figured out.
__________________
It's like riding a bicycle
urbanknight is offline  
Likes For urbanknight:
Old 07-23-22, 09:01 AM
  #45  
cyccommute 
Mad bike riding scientist
 
cyccommute's Avatar
 
Join Date: Nov 2004
Location: Denver, CO
Posts: 25,833

Bikes: Some silver ones, a red one, a black and orange one, and a few titanium ones

Mentioned: 138 Post(s)
Tagged: 1 Thread(s)
Quoted: 5232 Post(s)
Liked 2,791 Times in 1,647 Posts
Originally Posted by smd4 View Post
If you read the manuals, you’d know.
I have read manuals for chains, front derailers, and rear derailers. That’s how I know that chain sizing isn’t in the derailer manuals. It’s also how I know that the chain manuals say to size the chain in the big/big combinations and add 2 rivets.
__________________
Stuart Black
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Days of Wineless Roads. Bed and Breakfasting along the KATY
Twisting Down the Alley. Misadventures in tornado alley.
cyccommute is offline  
Old 07-23-22, 10:17 AM
  #46  
blinky
senior member
 
Join Date: Oct 2005
Location: Connecticut
Posts: 360

Bikes: 2003 Litespeed Tuscany with Ultegra R-8000 components

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 142 Post(s)
Liked 38 Times in 33 Posts
Here's a video with 3 methods explained by a jolly good follow :
blinky is offline  
Old 07-23-22, 10:55 AM
  #47  
Dave Mayer
Senior Member
 
Join Date: Dec 2006
Posts: 2,271
Mentioned: 17 Post(s)
Tagged: 0 Thread(s)
Quoted: 1004 Post(s)
Liked 299 Times in 189 Posts
Sigh.. so much angst..

Here is the only safe and reliable approach: wrap new chain tight directly around the big-big cogs. Determine the tightest possible way of connecting the chain, and then add one inch (2 links) of chain.

I volunteer at a high-volume big-city bike co-op. If we used either of the following approaches:
  1. Size based on the old chain
  2. Size based on wrapping around the small cogs front and rear.
We would have had multiple resulting equipment disasters - specifically rear derailleurs being torn off and the fragments being carried into the front derailleur and chainrings. We never assume that the old chain has been sized correctly. We also never assume that the bike we are working on conforms to any kind of acceptable manufacturer standard, and we assume that the drivetrain has been modified well outside functional tolerances.

We do see drivetrains with (modified) triple cranksets, and where someone has retrofitted a pie-plate cassette (11-40 teeth or bigger) onto a bike with a mid-cage derailleur. Of course, everyone needs a gear range of 20-200 gear inches.
Dave Mayer is offline  
Old 07-23-22, 12:39 PM
  #48  
blinky
senior member
 
Join Date: Oct 2005
Location: Connecticut
Posts: 360

Bikes: 2003 Litespeed Tuscany with Ultegra R-8000 components

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 142 Post(s)
Liked 38 Times in 33 Posts
Originally Posted by Dave Mayer View Post
Sigh.. so much angst..

Here is the only safe and reliable approach: wrap new chain tight directly around the big-big cogs. Determine the tightest possible way of connecting the chain, and then add one inch (2 links) of chain.

I volunteer at a high-volume big-city bike co-op. If we used either of the following approaches:
  1. Size based on the old chain
  2. Size based on wrapping around the small cogs front and rear.
We would have had multiple resulting equipment disasters - specifically rear derailleurs being torn off and the fragments being carried into the front derailleur and chainrings. We never assume that the old chain has been sized correctly. We also never assume that the bike we are working on conforms to any kind of acceptable manufacturer standard, and we assume that the drivetrain has been modified well outside functional tolerances.

We do see drivetrains with (modified) triple cranksets, and where someone has retrofitted a pie-plate cassette (11-40 teeth or bigger) onto a bike with a mid-cage derailleur. Of course, everyone needs a gear range of 20-200 gear inches.
This was the method promoted by Sheldon Brown and is outlined as Method 1 in the video that I posted above .
blinky is offline  
Old 07-23-22, 01:55 PM
  #49  
smd4
Senior Member
 
Join Date: Dec 2020
Location: Wake Forest, NC
Posts: 2,472

Bikes: 1989 Cinelli Supercorsa

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 1488 Post(s)
Liked 1,114 Times in 710 Posts
Originally Posted by cyccommute View Post
I have read manuals for chains, front derailers, and rear derailers. That’s how I know that chain sizing isn’t in the derailer manuals.
Chain sizing isn't in the derailleur manuals? Then what's this? I especially like that part that is titled "Chain Length."

Dura Ace Rear Derailleur Manual

Originally Posted by cyccommute View Post
It’s also how I know that the chain manuals say to size the chain in the big/big combinations and add 2 rivets.
The CN-7700 instructions don't address chain length. That's what the RD-7700 manual linked above is for. Nowhere in that manual is there any mention big/big plus 2 rivets.
smd4 is offline  
Old 07-24-22, 07:02 AM
  #50  
mitchmellow62
Full Member
 
Join Date: Aug 2014
Posts: 253
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
Liked 43 Times in 32 Posts
I'm curious if anyone has compared the different methods to see if the result differs?

Suddenly I can hardly wait for the next chain to stretch beyond spec!!! So far I think we have the following methods:
1. Match the number of links/full links/half links/rivets (whatever your nomenclature) of the old chain, which may have been sized by one of the following.
2. Big-big plus two links/two half links/one full link/one inch/two rivets (again, whatever your nomenclature) with chain NOT routed through rear derailleur.
3. Small-small, chain routed through derailleurs, with enough tension on derailleur cage to take it off its maximum take up.
4. Big chainring-small cassette cog, chain routed through derailleurs, rear derailleur cage pulled to vertical position.
5. Mathematical formula which I'm too lazy to recite and is my least favorite right now. So concrete. Where's the art?
I believe the caveat for at least some of these methods is that the largest cassette cog cannot be more than 36? And of course I have a number of RD manuals to read to see if Shimano has been consistent in their methods. I'm totally Shimano except for a couple of old Suntours. I wonder if they had manuals?
mitchmellow62 is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell or Share My Personal Information -

Copyright © 2023 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.