Chain length calculator

Could use some help here. I have a Trek Verve + 3 that I am increasingly riding off road, so new Puroma flat pedals went on today, Schwalbe Marathon 365 700x45 tires on the way, suspension seatpost and stem installed, chain guard removed...etc. Today I also received a SunRace 11-46 cassette (original is 11-36) and have a 136 link KMC X9e chain enroute. I have tools to change the cassette and chain. My chainring is 38 tooth. Derailleur is long cage Shimano Alivio. Original chain on the bike was 118 links.
Any recommendations on what a good chain length will be for my new setup? Thanks.
(I know, you’re probably thinking I should have just bought a Bulls Copperhead, but I can’t afford one :)) And it’s pretty flat country here for the most part.
 

Attachments

  • 4DBA4F76-A00A-494F-8AF2-3B447B24A1B9.jpeg
    4DBA4F76-A00A-494F-8AF2-3B447B24A1B9.jpeg
    934.9 KB · Views: 384
  • 7869AAE5-B2AF-4D94-A822-48CD332F419D.jpeg
    7869AAE5-B2AF-4D94-A822-48CD332F419D.jpeg
    499.5 KB · Views: 379
Last edited:
Latitude said:
Could use some help here. I have a Trek Verve + 3 that I am increasingly riding off road, so new Puroma flat pedals went on today, Schwalbe Marathon 365 700x45 tires on the way, suspension seatpost and stem installed, chain guard removed...etc. Today I also received a SunRace 11-46 cassette (original is 11-36) and have a 136 link KMC X9e chain enroute. I have tools to change the cassette and chain. My chainring is 38 tooth. Derailleur is long cage Shimano Alivio. Original chain on the bike was 118 links.
Any recommendations on what a good chain length will be for my new setup? Thanks.
(I know, you’re probably thinking I should have just bought a Bulls Copperhead, but I can’t afford one :)) And it’s pretty flat country here for the most part.
Click to expand...
This CHAIN SIZING VIDEO should help if you have your new gear setup installed. You can use a small rope in place of the chain to get the approx chain length you need if you don't have a chain yet. In current terminology a link is 0.5" so multiply the rope length in inches by 2 to get links. This technique works for short and most medium cage derailleurs. For long cage derailleurs, add 2 links. Hint, never round down in measuring your chain length, always round up to the nearest even measurement, i.e. a measurement of 61.3 inches would indicate a chain length of 122.6 links, round up to 123 links, make it even at 124 links. Order a 126 link chain and take a couple of links off.

You can also the formula published by PARK TOOL or this CALCULATOR that produces similar results. You will need to measure your chain stay length to use either of these calculators.

From Park Tool:

Simple Equation: L = 2 (C) + (F/4 + R/4 + 1)

L = Chain length in inches. Round the final result to closest whole inch figure. C = Chain stay length in inches, measure to closest 1/8″. F= Number of teeth on largest front chainring. R= Number of teeth on largest rear cog.
 
Sierratim said:
This CHAIN SIZING VIDEO should help if you have your new gear setup installed. You can use a small rope in place of the chain to get the approx chain length you need if you don't have a chain yet. In current terminology a link is 0.5" so multiply the rope length in inches by 2 to get links. This technique works for short and most medium cage derailleurs. For long cage derailleurs, add 2 links. Hint, never round down in measuring your chain length, always round up to the nearest even measurement, i.e. a measurement of 61.3 inches would indicate a chain length of 122.6 links, round up to 123 links, make it even at 124 links. Order a 126 link chain and take a couple of links off.

You can also the formula published by PARK TOOL or this CALCULATOR that produces similar results. You will need to measure your chain stay length to use either of these calculators.

From Park Tool:

Simple Equation: L = 2 (C) + (F/4 + R/4 + 1)

L = Chain length in inches. Round the final result to closest whole inch figure. C = Chain stay length in inches, measure to closest 1/8″. F= Number of teeth on largest front chainring. R= Number of teeth on largest rear cog.
Click to expand...
Thanks Sierratim!
 
Sierratim said:
Simple Equation: L = 2 (C) + (F/4 + R/4 + 1)

L = Chain length in inches. Round the final result to closest whole inch figure. C = Chain stay length in inches, measure to closest 1/8″. F= Number of teeth on largest front chainring. R= Number of teeth on largest rear cog.
Click to expand...

To use an industry term... dead_on_balls_accurate. As that is what my bike came with new and what I've continued to use.
 
So I made the calculation with the yellow calculator provided here. It suggested 60” or 120 links, add two links for long derailleur= 122 links
Using the Park Tools formula, I come up with 61 1/2” or 123 links (no factor for long derailleur. So it looks like I should be safe starting with 123 links.
(46 T rear cog, 38 T front chainring, 19.75” chain stay length.)
 
Latitude said:
So I made the calculation with the yellow calculator provided here. It suggested 60” or 120 links, add two links for long derailleur= 122 links
Using the Park Tools formula, I come up with 61 1/2” or 123 links (no factor for long derailleur. So it looks like I should be safe starting with 123 links.
(46 T rear cog, 38 T front chainring, 19.75” chain stay length.)
Click to expand...
I'm using the calculators to order chains that will work. Looks like you should order a 126 link chain. When it arrives I'd advise fitting it per the video by wrapping it around the largest cog and chain ring then adding 4 lnks for a long cage derailleur, 2 for a medium. Always works for me! 😎
 
I went with 123 links, and it seems about right... derailleur cage is pretty much vertical in mid-gear. The top gear in the derailleur cage was meshing with the 46 T low gear initially causing some noise and problems shifting out of 1st, but I have adjusted it as far away as it will go and after brief riding, seems to be quieting down. Not shifting entirely correctly yet, especially going into 9th, but working on it. Thanks for all your help mates!

4D0BF62A-04AF-44C0-BD21-9D829B53AF28.jpeg
 
Last edited:
50 km ride today, including some paved (not streets) and grassy hills that I needed to take a bit of a run at with my original cassette. I was able to ride up them with ease. This setup is much better for my mix of road and trails. Trails are starting to get wetter this fall here, so looking forward to new Marathon 365 tires arriving.
 
@Sierratim, @TS25: The chain with 126 links on the 48T chainring and with the 11-46T cassette with SGS derailleur on Vado 5 is close to the ideal you both described. My feeling is 124 links would make no harm either... So I stand corrected and intend to follow your advice to an iota in the future! :)

Besides, a friend has send me brand new CN-TL10 pliers as a gift :)
 
Last edited:
Stefan Mikes said:
@Sierratim, @TS25: The chain with 126 links on the 48T chainring and with the 11-46T cassette with SGS derailleur on Vado 5 is close to the ideal you both described. My feeling is 124 links would make no harm either... So I stand corrected and intend to follow your advice to an iota in the future! :)

Besides, a friend has send me brand new CN-TL10 pliers as a gift :)
Click to expand...
A new chain, and a new tool! That'd be almost too much excitement for me...🤣

I'm happy it worked out well. I assume your shifting is smooth and crisp?

I think I mentioned that my sons run their chains on the short side to get more tension in the largest cog to minimize chain slap on steep descents on their MTBs. My point being that you do have some discretion on chain length with the spring loaded derailleur making it all work.
 
Last edited:
Latitude said:
I was able to get a 9 speed KMC chain at 136 links on Amazon
Click to expand...

Good to know but it didn't come up in my search...next time!

Edit: Just did a search for KMC 9spd 136l chain on Amazon and it didn't show up....Did so on Google and the first listing was for the right item on Amazon.....however the two chains I ordered were $3 more than the 136 so I'll have plenty of extra next change to just get the cheaper 116 one and into the future.

Edit 2: Well I got the chains and joined them together and using my big chain ring, well only chain ring a 42t, and the 11t on the cassette as a starting point with the cage as so that it is as slack as possible but still with tension I put the chain together and low and behold it wanted to join at the joint I had made. So I took off the other chain and hooked it up and held my breath as I went up the cassette and with a little fiddling of the b tension screw and cable tension it hopped up onto the 50t just fine. So 116l it is for my purposes and bonus because I now have a whole spare chain! I guess I must have taken some links from the chain with my 46/42t setup and forgotten...
 
Last edited:
Latitude said:
I was able to get a 9 speed KMC chain at 136 links on Amazon
Click to expand...
How is your shifting and noise ? I ask because I have teh 2020 Verve 3 in a generic Bike : It has the identical components you have . It came standard with 46 T Sprocket : I counted the links at 121 : I just changed My Vado from 40T to 48 T : At 40 Teeth the chain was 121 > Now it's 124 > I also noticed it was slightly nosier: SO I re-torqued My chainring Bolts and the Noise is Gone : You should have made no difference in shifting by adding a larger Sprocket If the nose persists : I would pop out 2 links > I'm saying 2 because it's likely that's what will take to to the correct connection spot with links:
 
Last edited by a moderator:
BarryS said:
How is your shifting and noise ? I ask because I have teh 2020 Verve 3 in a generic Bike : It has the identical components you have . It came standard with 46 T Sprocket : I counted the links at 121 : I just changed My Vado from 40T to 48 T : At 40 Teeth the chain was 121 > Now it's 124 > I also noticed it was slightly nosier: SO I re-torqued My chainring Bolts and teh Noise is Gone :
Click to expand...
It‘s working perfectly and quietly now that it’s settled in. I was unable to get it to shift into 9th initially... the SunRace cassette has a spacer on the inside which moves the whole unit out further than the Shimano 11-36, and I was unable to adjust the H screw to get the derailleur out far enough for 9th. I put a thin washer between the derailleur and its hanger to move it out slightly, and that made it work. Now that it’s settled in, I may try to remove the washer... or not, since it’s working well.
 
JRA said:
Good to know but it didn't come up in my search...next time!

Edit: Just did a search for KMC 9spd 136l chain on Amazon and it didn't show up....Did so on Google and the first listing was for the right item on Amazon.....however the two chains I ordered were $3 more than the 136 so I'll have plenty of extra next change to just get the cheaper 116 one and into the future.

Edit 2: Well I got the chains and joined them together and using my big chain ring, well only chain ring a 42t, and the 11t on the cassette as a starting point with the cage as so that it is as slack as possible but still with tension I put the chain together and low and behold it wanted to join at the joint I had made. So I took off the other chain and hooked it up and held my breath as I went up the cassette and with a little fiddling of the b tension screw and cable tension it hopped up onto the 50t just fine. So 116l it is for my purposes and bonus because I now have a whole spare chain! I guess I must have taken some links from the chain with my 46/42t setup and forgotten...
Click to expand...
It KMC E9 That's all you have to type : https://www.amazon.com/KMC-X9e-Turbo-Bicycle-Silver/dp/B00SM1OJRO
 
Anyone recommend a decent replacement chain setup for the truck run in the lectric xpremium? Stock it has the 7 speed 12-32T rear freewheel. Replaced it with a nickel plated DNP 11-34. The front is still running the 58T double-sided chainring, cheapo shimano tourney derailleur, 7-speed shimano sram thumb shifter.

Length of chain stay is 19.5" or 495.3mm
 
Last edited:
You must log in or register to reply here.

Similar threads

JGcycle
Chain Replacement Question
Replies
3
Views
628
JGcycle
JGcycle
B
Correct chain length on Turbo Creo SL?
Replies
9
Views
2K
bobf
B
Jeremy McCreary
Chain length dilemma: Who to believe?
2 3 4
Replies
67
Views
5K
Gionnirocket
Gionnirocket
Rich W.
A few drivetrain questions:
Replies
7
Views
1K
Nomad
N
Stefan Mikes
Myth BUSTED: "The Chain Drops On My Specialized E-Bike Because The Chainring Is Praxis WAVE"
2
Replies
29
Views
6K
pete H
pete H
Back