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How to Size a Bicycle Chain

How to Size a Bicycle Chain


Replacement chains for bicycles are always longer than you need. In this video we’ll take you step by step through chain sizing. Hello, Calvin Jones with Park Tool company. If you’re working on a bike with a single speed, or a bike with a Campagnolo derailleur, we have separate videos that cover sizing for those systems. Before we begin, let’s define the chain types. There are master link chains and connection rivet chains. Master Link chains use two removable outer plates to connect the chain. Connection rivet chains use a special rivet to connect the chain. Tools needed for sizing are a chain tool to cut the chain, and you’ll need a master link pliers
for chains with master links. Lastly, if you’d like to learn other procedures and concepts related to chains, be sure to check out our guide to chains
for an overview of what we have available. Before we remove the old chain,
we need to confirm it’s the correct length, so we’ll shift to the largest front and rear sprockets. The chain should be able to make this shift, and it should have two slight bends, one at each pulley. Next, shift to the smallest sprockets. There should be no slack in the chain, and the derailleur should not pull so far back that the chain contacts itself. So in this example, the chain is sized correctly
and can be used to size our new chain. Now we remove the chain, and an option is to first remove the wheel. This takes tension off the chain,
and makes things a little easier. Inspect the chain for a master link. If a master link is present, use a master link pliers such as the Park Tool MLP-1.2 to disengage the link. Alternatively, you could use needlenose pliers, but it’s difficult at best. And doing it by hand is extremely difficult. If you have a chain tool, and your chain is worn out, you could ignore the master link and simply break the chain the same way you would on a connecting rivet chain. We’ll walk through that process next. Connecting rivets will appear visually different from the other rivets. When selecting a rivet to break, be sure it is at least a couple links away from any connecting rivet already installed in the chain. Install the chain tool, and bring the driving pin of the chain tool into contact with the rivet. Ensure the chain tool pin is driving in a straight line into the chain rivet. Turn the handle with force and drive out the rivet. Remove the chain. If the old chain is an acceptable length,
lay it next to the new chain as shown. Always line up ends with outer plates. This example is incorrect because we have an end with outer plates being compared to an end with inner plates. Insert the master link to get a true side by side length comparison. In this other example, neither end of the chains have outer plates so in this case we would line up
inner plates at either end. Next we line up the chains. Take care to match them rivet by rivet, noting that old chains will lengthen as they wear. This is the rivet that we will cut on the new chain. …and the chain is sized. See this other video for a full walk through of the installation process. When we are not matching the length of an old chain, we use the largest cog and largest chainring method. The vast majority of drivetrain manufacturers use this method. There are some exceptions and considerations,
and we’ll cover those after we show you the process. First, shift the front derailleur over the largest chainring, and the rear derailleur to the smallest cog. We begin by wrapping the chain around the largest cog. If the new chain has one end with an outer plate,
it should be routed toward the front chain ring. Pass the chain end through the front derailleur cage onto the largest front chainring. Hold at about the 5:00 position. If the chain uses a master link,
install half of the master link. This will account for the extra 1/2 inch the master link provides. With this plate installed, the rest of the process is the same for master link and connection rivet chains. Pull the lower section of chain snug, and engage it on the chain ring. Make sure the chain is fully on the largest cog. Note that we bypassed the rear derailleur altogether, and extra length will be added to account for this later. Now we find the closest rivet
where the two ends could be joined. The inner plates on this link would match up with the outer plates on the other link. Because they can be joined here, we’ll call this our reference rivet. From that rivet, we add an additional two rivets. This is the cutting point. In can occur that when we pull the lower section snug, an outer plate meets an outer plate. This cannot be our reference rivet because it is impossible to join the chain here. So me must add another rivet, making this our reference rivet. From here, we would add two additional rivets. This is our cutting point. We cut the chain with our chain tool and the chain is sized. and that is the common largest cog to largest chainring sizing method. For a walk-through on installation, see this other video. There are a few exceptions to the rule of adding two links, as well as some other considerations. If the bike uses a chain guide, be sure the chain is routed through the system before determining chain length. Add the same 2 rivets as before to establish the cutting point. The amount of rivets added is different if you have the following combination of components: A SRAM derailleur with an 11 or 12 speed cassette.
and a single front chainring with no suspension. With this system, add four rivets from the reference point. This would be our cutting point. The next consideration deals with rear suspension bikes. The distance between the rear cogs and the front rings will change as the suspension moves for bumps. To account for that, we disconnect the shock and compress the linkage. This is the maximum possible distance between front and rear sprockets. With the suspension held in place, we use the same technique as before, adding two rivets for the cutting point. Again this is for all bikes with rear suspension, including SRAM 11 and 12 speed 1X systems. Thanks for watching this repair help video from Park Tool. We’re constantly adding videos and articles here on YouTube as well as our website at parktool.com Please give this video a thumbs up if it helped you out. and of course, subscribe
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100 comments on “How to Size a Bicycle Chain

  1. I thought the instructions were clear but this doesn't work for the new Ultegra (8050=Di2 at least, perhaps mechanical too). I followed the instructions to the letter and ended up with a way too short chain length. Now I have to buy a new chain.

  2. Adding to my comment below: I was referring to measuring the chain length using the large/large method. Upon further research, it appears that method is only indicated for sprockets 27T and larger, per Shimano chain installation instructions. My cassette is 11-25. For that size , they advise the second method: large chain ring /small sprocket (with chain routed through rear derailleur). That resulted correctly in 3 extra links needed, see page 9 here: http://si.shimano.com/pdfs/dm/DM-CN0001-05-ENG.pdf . As a side note and unrelated to the above 2 methods, the instructions contain some errors and ambiguities on page 5 (and I would not praise Shimano instructions elsewhere, they appear to be translated from Japanese with Google Translator, I am appalled how such a large company doesn't care to provide clear instructions using English terminology..)

  3. Am going to replace complete drivetrain + front and rear derailleurs + cables because I know it's well past due. As I am saving up for that + other things as well, I thought I could at least do a temporary fix(chain did overshoot the upper front cog while shifting up) with a new chain. Cutting the new chain to correct length still made it skip on some cogs, so at least I learned that I was right about deciding to go for a complete change. I found out the old chain was too long, so I cut that one and now it at least don't overshoot the upper front cog, and does not skip any cogs at all, under heavy load.It's a temporary fix, and I learned a lot. Long term is the way to go, and I've always done that with motorcycles as well, only that on motorcycles I always change both sprockets and chain at the same time. On a bicycle I will just start cutting the first chain to size, and follow that till the full drivetrain has run through enough chains that it's about that time again. I'm also going to get a chain checker.
    Even though it did cost me a small amount of money now, it will save me lots in the long run, as I do learn from my mistakes. Do things proper – have the right tools, and so on.

  4. Good video, since I am trying to learn all I can about bike repair, more than I ever did in the past when I did alot of riding, but now that I am older, and getting back into riding, I've bought some project bikes to practice on before I touch my two quality bikes(or any I might order this year). Yeah, putting on a new chain on a project bike,….I figured it wasn't that easy, and I measured the links on the older chain without a master link after I already cut the rivet previously, but I worry if the chain was ever set up right, I mean, it was a quality bike rode little but set aside to deteriorate, I didn't even want to use my park tool wear measure tool cause the old chain had rust,….but its a learning tool, that old bike, and another old bike, I mean, I am your typical middle aged man, still able to get back into riding after a number of years not doing so, and its fun to learn how to service bikes, like replacing spokes, truing wheels, etc. One of these days I hope I can have many many tools to repair bikes, maybe even as a sideline to make extra money due to a strange shortage of bike mechanics locally. After I do the chain, I do replacment 21 speed shifters, then the adjustment learning curve on a new setup,….I am getting alot of tools lately. I might even do some youtube videos to help encourage other guys, even gals,..my age, that they too can get over the fear of working on their own bikes, or at least knowing more, ..hey, if a guy like me can do it, anyone can, haha,…..good thing i am practicing on low end used bikes and low end replacment parts for now,…I even bought a department store el cheapo bike to understand them more,…and believe me, I have had a few of them in the past in the 1990's, its amazing how some things never change, how the lower end ones are so needing a very knowledgable home bike mechanic, sometimes for major things wrong with them(another reason I am eyeing a entry level quality road bike to go with my older Giant entry level mountain bike. Besides all that, I have formal college and military training in mechanics, an associates degree in applied sciences for automotive and industrial sciences, I once was a certified ASE Master Automotive Technician, so I understand tools and mechanics, this bike mechanic practices comes easy for me, I mean, I've done alot of serious bike services in the last month I always dreamed of doing.

  5. If there were awards for YouTube videos, Park Tool would win hands down in the "How-To" category. They are clean, consistent, professional, clearly scripted, well organized, step-by-step…I could go on and on. Excellent way to promote the purchase of high-end tools and ensure happy customers after the sale, having empowered them to do the job right. If I owned a bike shop and hired a new mechanic or had an employee wanting to transition into that position, I would point them to the Park Tool channel and say "watch every video, then we'll let you start touching the bikes". Great as usual.

  6. Tip for anyone installing a new chain on a on large rear cog shimano 1 by drivetrain (46 tooth in my case) where you don’t have an old chain to use as reference…I had to add 6 rivets from the reference link to get the right size when bypassing the rear mech. So double/triple check before you break the chain 😉

  7. If i had a sram 12 speed and a full suspension then the chain wouldnt be long enough. With my suspension off on the biggest rear sprocket and my only front sprocket plus 2 rivets leave me removing 1 link.

  8. I have a folding bike with a 1x system. it's not a Sram drivetrain, but some taiwanese brand. should I follow the 1x for Sram you mentioned in this video?

  9. My road bike has Shimano system. I followed the instructions, especially the way 4:02 for chain sizing, to replace the chain myself. Went out to ride for 40 miles with 2000 feet elevation gain, no problem. Thx for the tutorial.

  10. this video wasnt really what I was looking for because I was searching for the wrong thing BUT I must accept that I watched the whole video just because of the good quality of it, I was suprised of how well explained it was, highlighting and showing examples of your explanation, just perfect! I wish there was more channels (tutorials) in youtube like yours.
    well done sir

  11. Really useful thanks.
    Just a quick question though, any specific consideration for chain sizing when using oval chainrings?

  12. I use a XT m8000 1×11 groupset, except an 11-46 cassette and a 42t (!) front chainring. There was not much other choice than to just attach the included quick link, and say a quick prayer. The chain may be a link or two too short, but I can sort that with a few extra quick links later. No need to remove the shock at least. 😛

  13. Calvin, I didn't watch this video, because you've already taught me to do this several times over. But I did want to drop a note to thank you for YEARS of teaching me how fix bikes. The Big Blue Book was where I learned first. I still have a copy that is in such bad shape I don't know if can ever use it again. It's seen beyond dog-eared… All the YouTube videos have been a blessing as well. Nearly everything I know has either been from you or from mistakes I made because I forgot lessons you taught. THANK YOU. Have a wonderful 2019!!!

  14. Hello and thanks for these fantastic tutorials.
    Is the rule of +4 (instead of +2) due to large cogs (over 40T) or due to 11speed ?
    I have a 10speed 11-42T (full suspension), would you recommand +2 or +4 rivets ?
    Thanks

  15. Just converted to one by ten with a 30 tooth front sprocket sprocket from a two by ten setup should i shorten my chain

  16. WHY NOW I JUST STUGGLED for 5 hours with my chain …. I mean youtube suggested it now … all well better late then never.

  17. It is simple just to attach the chain to the 2 smallest cogs and just size so that jockeys only just move. No need to do anything else. Dont forget to factor in the master link

  18. I personally size my chain with the following procedure. Shift into the smallest cogs and keep the chain as long as the chain doesn't rub on the rear mech. That way you have less chain tension, wear and load get spread through more links and the chain will potentially have longer service life. Yes, reduced chain tension might lead to more frequent chain drops, but IME, this doesn't happen during regular riding all that often

  19. Great video but one question for you…I have a full suspension bike with an 1×11 speed sram rear derailleur and a 34t oval on the front. Can you give me your best advice on how many links to add? Thanks!

  20. question: my brand new e-bike has a chain much longer than this. There's a lot of slack in the chain, even in the biggest gear. Does this chain sizing advice apply to e-bikes?

  21. Hi Guys, can you add a comment on sizing chains with an oval front chain ring please? Presumably you would need to orientate the longest dimension of the oval vertically, to ensure you have a sufficiently long chain? Or does it make no difference? Thanks

  22. Look if you're not spending 10 minutes swearing out loud trying to break the masterlink by hand are you even really trying to be a DIY bike mechanic?

  23. Great reference video (thanks). Question regarding the exceptions at the end. At 5:45, you specifically mention SRAM 1 x 11- or 12-speed as an exception, in which case you'd add 4 extra rivets. How about Shimano XT? Same scenario (hardtail bike) with Shimano XT 1×11 drivetrain?

  24. Super instruction!!! Great help, considering the remarks on 11-speed & full-sussers!! Very helpful, thank you!!!

  25. So is this why my new chain on my new cassette slips/jumps under torque in the smaller gears? I was using the manufacturer supplied length!

  26. They even had a blue marker! But was anyone else disappointed to see it was a Sharpie? I was expecting a Park Tool BM-1 (Blue Marker #1).

  27. So what about 3×10/11/12? I'm sizing for a recumbent trike that needs the gear range of a 3x.
    edit: SRAM NX for reference.

  28. But for Sram Eagle on a full suspension bike, do we add 2 or 4 extra rivets? Sram recommends adding 2 rivets on full susp with Eagle.

  29. Awesome! What if you have a full suspension with 1x and it's shimano? Would you use the 2 rivit space or 4? Thanks

  30. The way you add two additional rivets to measure where the chain should be cut is different from the advice in this video https://www.youtube.com/watch?v=rWchudX-Tqs (check at 3mins 15secs). He added two whole links and you added only two rivets which is very different. Now I am wondering which one method is correct??? And I am changing my chain tomorrow for the first time!

  31. This chain sizing is not correct as some rear derailleurs have large bottom jockey wheels which require a longer chain or else they will push the upper jockey assembly to far forward. The top jockey wheel should always be centered underneath the Freewheel or Cassette. A shorter chain will push the upper jockey wheel away from the center underneath the cassette or freewheel. 7 speed freewheels with a large bottom jockey wheel with 3 chain rings require an 8 speed chain ( cut down to fit properly). The upper jockey wheel should always be centered underneath the cassette or freewheel. This video here is for short and long cage derailleurs with small jockey wheels.

  32. Also, if there're 11 gear wheels the chain should be longer than if you have 10 gear wheels. Should add this to consideration as well.

  33. I followed your instruction and now the cage fouls the cassette if I try and select either the two largest gears. Maybe you should have mentioned cage length?

  34. Awesome. I acquired a nearly new bike with no derailleur and a chain in multiple pieces. Hang on to your hats boys. I’m goin’ in.

  35. I'm not sure about this but… I got very familiar with chain length vs. suspension geometry on dirt bikes and it played out differently between various brands and models. When the three points (crankshaft, suspension pivot and rear axle centers) are in a straight line then the chain distance is the longest. On any angle other than straight then the distance becomes shorter. The green bike in the video appears to be making a angle when you unhook the shock and strap it up, I might be wrong. I think you do have to consider the different designs to know where you move the swing arm to.

  36. Learned so much from you guys at Park Tool, serviced /replaced front and rear wheel bearings, replaced gear cables, cassette remove and clean, chain replacement plus adjusting front and rear derailleur. …your videos are appreciated, Thank you….

  37. Bosch motor eBike: I have a single, very small front sprocket (15 tooth?), 11-speed cassette, Shimano derailleur. Use basic measuring method?

  38. first off , HAts off to park tools for the excellent videos…
    so i tried this on my intense 5.5 and the chain still was too long . i removed the shock and pulled the wheel up to the frame for max distance from as shown in the video for a full susp.. setup. put the chain on both large rings and then removed link at the two rivet point. i mounted the shock and noticed the derailleur was all the way tucked back and the chains were rubbing. so i removed another link and then it seemed to have been the perfect length. could this be due to the vpp link allowing the frame to pivot more than normal? when the shock was removed? i checked it again to make sure i did everything right … anyway may the problem is im riding a 2008 mountain bike… time to upgrade…

  39. I just got my ParkTool chain tool from a bike shop in downtown Eugene, Oregon. Now I know how to use it.

  40. Hi. I'm a little confused as to the two common methods mentioned on new chain sizing. Some recommend a big-big+2, others recommend a big-big+4. When should I use each of them? I've used the big-big+1 successfully on my 2x road bike, but im building a 1x gravel bike with an ultegra rx RD on a hanger extender paired with an 11-40t cassette. I see many MTB guides featuring the +4 method. Should I do the same in my case? Thanks

  41. The masterlink pliers sound very nice for a shop setting, though for folks at home that forgot to purchase a pair, I have found that disengaging the links by hand is better than a needle nose pliers. With the chain under low tension or no tension, use one hand to press the two plates of the masterlink together which tends to unseat them from their pin grooves. At the same time with the other hand, using index finger and thumb you can often quite easily slide the masterlink plates past one another. Harder to do under tension as you could imagine the other chain links getting in the way when trying to slide the the masterlink plates.

    Bam, very easy, though rubber gloves needed to avoid chain oil on the hands. Still, masterlink pliers look to be faster yet.

  42. Hey I got confused on the sram 1x system chain sizing with no rear suspension. So my question is "I have a 1×10 Shimano deore on my hardtail, do I have to add 4 links or just 2 links?".

  43. Park tool videos are indeed great! One note on this video however! Make sure you watch it ALL they way before cutting. I was just about to cut, but fortunately decided to watch the video all the way through. There are a number of exceptions, which are mentioned only at the end. Most notably full sus and hardtails with SRAM 11/12 spd.

  44. Thanks for the thorough explanation.

    I can't figure out one thing, however. Please help if you know the answer.

    Road bike. SRAM Rival 1 medium cage. 42 front, 11-40 cassette.

    Problem: when I added four links I have slack in the chain when I switch to the smallest cog.

    I removed two more links, still slack but less. I added Goatlink (not a Roadlink, not sure if they are different ) and still a problem. In fact, it looks like goatlink made slack even more.

    Do you think switching to Rival 1 large cage is the only way to go? or should I cut two more links?

    thanks.

  45. I have to use a ebike chain cause I live 40 miles from work and bike. Thanks nobody really like me I'm Azteca Dancer. I ride 29"with a load I noticed in middle front and middle cassette was skipping I cleaned it. I think a little bit more chain out will change it in on my last Shimano chain nobody knew there ebike chain so I went German whiperman 808. I'm hopping for more torque ability. I have 2008 rockhopper the bolt to Oregon reach I bought a month ago. Specialized I think told me just take it in. I noticed that had a 1 year on it. I bike up and down 7% 1/4 mile 495ft drop and it's a new bike , disc brakes on back are not locking up rear wheel I'm changing pads. Sanding rotors spinning wheel. See if it improves.

  46. Наконец-то полезное видео. А то посмотрела, где советовали закинуть цепь на большую звезду спереди и самую маленькую сзади, и так укоротить. Теперь не могу ездить на третьей звезде =/

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