00:00Replacement chains for bicycles are always longer than you need.
00:03In this video, we'll take you step-by-step through chain sizing.
00:14Hello, Calvin Jones with Park Tool Company.
00:16If you're working on a bike with a single speed, or a bike with a Campagnolo derailleur,
00:21we have separate videos that cover sizing for those systems.
00:25Before we begin, let's define the chain types.
00:28There are master link chains and connection rivet chains.
00:31Master link chains use two removable outer plates to connect the chain.
00:35Connection rivet chains use a special rivet to connect the chain.
00:39Tools needed for sizing are a chain tool to cut the chain,
00:42and you'll need master link pliers for chains with master links.
00:46Lastly, if you'd like to learn other procedures and concepts related to chains,
00:51be sure to check out our Guide to Chains for an overview of what we have available.
00:59Before we remove the old chain, we need to confirm it's the correct length,
01:02so we'll shift to the largest front and rear sprockets.
01:07The chain should be able to make this shift,
01:10and it should have two slight bends, one at each pulley.
01:17Next, shift to the smallest sprockets.
01:21There should be no slack in the chain,
01:24and the derailleur should not pull so far back that the chain contacts itself.
01:29So in this example, the chain is sized correctly and can be used to size our new chain.
01:36Now we remove the chain, and an option is to first remove the wheel.
01:40This takes tension off the chain and makes things a little easier.
01:44Inspect the chain for a master link.
01:47If a master link is present,
01:49use a master link pliers such as the Pug Tool MLP-1.2 to disengage the link.
02:00Alternatively, you could use needle nose pliers, but it's difficult at best.
02:05And doing it by hand is extremely difficult.
02:09If you have a chain tool, and your chain is worn out,
02:12you could ignore the master link and simply break the chain the way you would with a connection rivet chain.
02:17We'll walk through that process next.
02:20Connecting rivets will appear visually different from other rivets.
02:24When selecting a rivet to break,
02:26be sure it's at least a couple of links away from any connecting rivet already installed in the chain.
02:31Install the chain tool, and bring the driving pin of the chain tool to contact the rivet.
02:36Ensure the chain tool pin is driving in a straight line into the chain rivet.
02:42Turn the handle with force and drive out the rivet.
02:47Remove the chain.
02:58If the old chain is an acceptable length, lay it next to the new chain as shown.
03:03Always line up the ends with outer plates.
03:06This example is incorrect because we have an end with outer plates being compared to an end with inner plates.
03:12Insert the master link to get a true side-by-side length comparison.
03:17In this other example, neither end of the chains have outer plates.
03:27So in this case, we would line up inner plates at either end.
03:31Next we line up the chains.
03:36Take care to match them rivet by rivet, noting that old chains will lengthen as they wear.
03:42This is the rivet that we will cut on the new chain.
03:47And the chain is sized.
03:54See this other video for a full walkthrough of the installation process.
04:02When we are not matching the length of an old chain, we use the largest cog and largest chainring method.
04:08The vast majority of drivetrain manufacturers use this method.
04:11There are some exceptions and considerations, and we'll cover those after we show you the process.
04:17First, shift the front derailleur over the largest chainring and the rear derailleur to the smallest cog.
04:23We begin by wrapping the chain around the largest cog.
04:27If the new chain has one end with an outer plate, it should be routed toward the front chainring.
04:33Pass the chain end through the front derailleur cage onto the largest front chainring.
04:38Hold at about the 5 o'clock position.
04:42If the chain uses a master link, install half of the master link.
04:46This will account for the extra one half inch the master link provides.
04:50With this plate installed, the rest of the process is the same for master link and connection rivet chains.
04:56Pull the lower section of chain snug and engage it on the chainring.
05:00Make sure the chain is fully on the largest cog.
05:06Notice that we bypassed the rear derailleur altogether, and extra length will be added to account for this later.
05:13Now we find the closest rivet where the two ends could be joined.
05:16The inner plates on this link would match up with the outer plates on the other link.
05:21Because they can be joined here, we'll call this our reference rivet.
05:25From that rivet, we add two additional rivets.
05:29This is the cutting point.
05:31It can occur that when we pull the lower section snug, an outer plate meets with an outer plate.
05:45This cannot be our reference rivet because it is impossible to join the chain here.
05:49So we must add another rivet, making this our reference rivet.
05:53From here, we would add two additional rivets.
05:57This is our cutting point.
06:01We cut the chain with our chain tool
06:12and the chain is sized.
06:14And that is the common largest cog to largest chainring sizing method.
06:19For a walkthrough on installation, see this other video.
06:23There are a few exceptions to the rule of adding two links, as well as some other considerations.
06:32If the bike uses a chain guide, be sure the chain is routed through the system before determining chain length.
06:38Add the same two rivets as before to establish the cutting point.
06:45The amount of rivets added is different if you have the following combination of components.
06:51A SRAM derailleur with an 11 or 12 speed cassette
06:55and a single front chainring with no suspension.
07:00With this system, add four rivets from the reference point.
07:04This would be our cutting point.
07:07The next consideration deals with rear suspension bikes.
07:10The distance between the rear cogs and front rings will change as the suspension moves over bumps.
07:16To account for that, we disconnect the shock
07:22and compress the linkage.
07:27This is the maximum possible distance between front and rear sprockets.
07:31With the suspension held in place, we use the same technique as before,
07:35adding two rivets for the cutting point.
07:38Again, this is for all bikes with rear suspension, including SRAM 11 and 12 speed 1x systems.
07:46Thanks for watching this repair help video from Park Tool.
07:53We're constantly adding videos and articles here on YouTube as well as our website at ParkTool.com.
07:59Please give this video a thumbs up if it helped you out,
08:02and of course, subscribe for the latest content from Park Tool.
