What amount of bicycle chain wear ('stretch') is acceptable, before damage to sprockets ensues?

Question

Have seen 1/16 inch in 12 inches (12 links) referred to as time to change (www.sheldonbrown.com/chains) and would like to gauge the range of opinion on this number.

I am approaching this wear level now, though I have religiously (weekly) cleaned the chain with a cleaning tool (BB brand) and 'gallons' of citrus-type solvent and water, and have lubed with a synthetic oil for wet conditions (Pedro's) everyday. Shoulders here are often sand-covered or muddy, and I often must commute in/after downpours.

To be precise, my Shimano HG narrow (with 9-spd cassete) is at 1/32 stretch after about 5 months and 2000 km (about 1,250 miles). This begs a secondary question: Is this a reasonable wear rate?
Thanks for your ideas.

Answer 1

Hi there. You provide a lot of details and so do the other respondents.



However, if you're being that specific and precise, you're probably thinking way too hard about this:



First riding conditions vary. Sounds like you're riding in some relatively harsh conditions so your chain wear will be higher.



Second, you seem to spend a lot of time conditioning your drivetrain. While I certainly applaud you for doing so, do you really have that much free time?



Bottom line is that new chains are cheap (in the grand scheme of things) -- you can't fill up most cars with a tank of gas for the price of a new chain. Factor in the time you spend caring for your chain (along with aggravation of wondering how long you should use a chain) and you might as well replace your chain every 1000 miles (or even sooner if you'd like).



Don't get me wrong, taking care of your equipment is a really good idea and some people live to do nothing more than that. However, if you're so worried about damaging your rear cogs, just replace the chain more frequently than you think you should...it's cheap insurance and certainly less time consuming than constantly washing your drivetrain.



P.S. If you're worried about the environmetal impact of replacinig your chain, you can always recycle the chain.

Answer 2

My rule of thumb was 3 months or 12 miles. I believe the Shimano or Sedis rule was 2500km, so you are about there at 1200 miles. I belive this is a reasonable rate of wear.



The "old rule" I used to see a lot was 1/8 of an inch, at which point you would need to replace the entire drivetrain, so that was way too much.



Afterreading your story I'm worried about you rear hub abd bottom bracket. If you are seeing that much mud and sand, and washing the chain with citrus the bearing grease/cavity may be contaminated. It's a pain, but I like to overhaul my hubs at leas twice a year - Seattle. The Shimano grease is excellent.



Good luck.

Answer 3

Well, you've already got the details right and just don't want to buy a chain?



Okay, the Dura-Ace/XTR is much harder material and not as prone to stretch.



Yes, 1/16th is correct for being within safe limits.



2000 miles of open road or 1000 miles of city is the correct figure for Shimano and SRAM chains. Wipperman (Campy) can go twice that distance at about twice that cost. Same $ per mile. Many mountain bike riders run the Wipperman chain with Shimano gears. In my opinion, this isn't a good idea unless that's the only chain you can't snap.



Try this:



Before you put the new chain on the bike, wash it (the chain) with Simple Green and dishwashing liquid to remove the cosmoline. The next day flood it with Singer Sewing Machine oil rubbing it in very well with a washrag. This lubes the inside of the chain. Dry it well. Now, apply EPIC (clear form of White-Lightening) to the chain to make it non-stick. EPIC is clear, and thus effective. Goopy chain lubes don't do anything but fall off. Continue using EPIC throughout the life of the chain.



Properly broken in, a Dura Ace chain could possibly last the proper 2000 or more miles that you should expect.



Feel free to apply EPIC plus washrag to the chain to "help" it with the dirt. This actually works well, even if you're in a hurry. It will knock off a lot of dirt and bring the friction down to within 10% of a freshly cleaned chain.



Oh, and did you measure pin center to pin center?



An exception: The 1/32 stretch is acceptable for steel cassettes, but not for titanium cassettes.



Yes, I agree with Sheldon Brown on all but 1 topic, and that would be 26" tires and that the oval contact patch of the mountain "slick" is, in my opinion neither as safe, nor as fast as the road bike tire with its pencil shaped contact, and, in my opinion many of the mildy treaded (road) 26" tires can, in fact, match the performance of road bike tires while the mountain "slick" cannot. He says the opposite. Hands-on experience conflicts in this one case.



Other than this one item, I have not found any inaccuracy in any of his articles. They are enjoyable and quite reliable.



So, if he says its time to buy a chain. . .then its time to buy a chain. ;)

Answer 4

Well I am a bmx racer and I have never gone as far as to actually measure the chain stretch. I can feel when the chain is starting to wear. I usually ride really hard on them and will change them around 1-2 months if they havent broke yet. Even if I havent rode super hard on them before a national I will change the chain to make sure im on somthing fresh. But for just a regular rider 2-3 months is average depending on how hard you are riding. I say once you can feel that it is stretched change it regaudless of what the guage says.

Answer 5

Man that is very precise. I know Park has a tool that can measure stretch. The website also has formulas for fit and size. http://www.parktool.com/repair/readhowto.asp?id=26



If your not getting the life out of your chain you might want to get a stronger chain. Maybe titanium if in your budget.

Answer 6

just change the change when you notice ANY stretching.. you'll have durable sprockets and chainrings