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    Chain Strength

    I was considering going to the Sunrace 11-42 10 speed freewheel, but read in the forum somewhere that 9+ speed chains were too weak for BBSHD?. Even if chain is thinner, I don't understand how that would make it weaker. Seems like pin diameter and plate thickness would be all that matters... Maybe the smaller chain to cog contact area makes them wear out faster? Maybe they won't fit on Lekie or Luna chain rings?
    I'm looking for info and advice before I throw my $$ down. Appreciate your comments on this subject.

    #2
    Good topic. I've been interested in chain strength on ebikes too. Is there a super chain for sale? An ebike specific chain?

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      #3
      There are some ebike specific chains. I haven't tried them, not sure how easy they are to purchase.
      Alan B

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        #4
        I have lots of miles on the SunRace 11-42. The 11 cog is the weak link, not your chain. The loosely cast SunRace 11t cog tends to skip on the freehub under e-bike power. Had this happen on two different bikes. Replace it with a Shimano 11t and you're good to go. Chain breakage is an often repeated Internet theory, but not really that much of an issue. KMC stretch-proof 10 speed chain and forget it.

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          #5
          Lots of experienced folks on ES indicate that cogs smaller than 14T don't last well on ePower, not enough teeth engagement, of course it depends on power. The higher power mid drives can snap a chain anytime by wrong gear choice and sudden application of torque. You want the chain to move fast and the tension to be low to carry lots of power. I'm running 9 speed chain but I avoid the cogs below 14 and start in 3rd or lower to reduce chain tension. No problems so far. Also important is the ramping of the throttle, gentle ramping avoids the huge torque peaks.
          Alan B

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            #6
            Check this out... "Special design for mid-motor e-bikes"? I've asked ....What makes it special?
            https://www.amazon.com/KMC-Chain-2X1...s=e-bike+chain

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              #7
              Alan summed it up real nicely.

              It doesn't seem to be a big issue for the BBS-HD. Don't let people scare you. I'm at something like 800 miles now on a KMC 10 speed chain with my first BBSHD. I do use the 11 cog, although I try to minimize that. I laid it out next to a brand new chain last Sunday to check wear (commonly called 'stretch'). Less than 1/16. No problem.

              Chains don't generally 'stretch' by metal yielding and changing shape. They wear out - the pins & holes get sloppy and thin, until the chain doesn't fit the cogs right. Chain gets longer due to all the little gaps. Then dirt gets in more easily, cogs take the load one tooth at a time instead of evenly sharing across several teeth, and so everything wears out faster and faster.

              Keep your chain lubed and clean so it won't wear too fast, and you should do fine. Let it grind away with dirt accumulation and you won't have very good durability. Worn chains wreck the cogs, too. Should replace as a set - worn cogs kill new chains fast, too.

              So, good incentive to keep your chain clean, on any machine, ebike or not.

              Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

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                #8
                Sheldon Brown (RIP) has some of the best web pages for bicycle maintenance, and you might want to look at what he has to say about chain maintenance:

                http://www.sheldonbrown.com/chainclean.html (this page is an april fools joke on chain maintenance)

                or better this, the real article:

                http://www.sheldonbrown.com/chains.html

                In summary, the new chain comes with really good lubrication, try not to "clean" that lubrication out of the chain, but do clean the exterior dirt, and when the manufacturer's lubrication wears out do apply lubrication. There are many ways to do this and many theories about what is best. I try to avoid the overcleaning and overlubricating, which Sheldon talks about.

                It is especially important with an ebike to monitor chain stretch (which is really a measurement of chain wear). Replacing the chain before it ruins the cogs will save you a lot of money. To make this easier a $7 tool is useful. It has two gauges, one for 0.75%, when this gauge fits the chain must be replaced. The other side has a gauge that measures 1.0% and when it fits, both the chain and the cogset needs to be replaced, a much more expensive repair. Try to catch it early and avoid the extra cost, at least for a few cycles.

                I purchased one of these gauges and tried it on a half dozen chains I have around here. None were worn enough to replace. Most are hubmotor bikes which tend to make chains last a long time, one is the BBSHD with 1300 miles, and it too wasn't taking the 0.75% gauge yet.

                1/16" stretch in a 44" chain is 0.14%, so not too bad.
                Alan B

                Comment


                • JPLabs
                  JPLabs commented
                  Editing a comment
                  I use 118 links I think.... So, that would be 59 inches, right? Thus only 0.11%. Small difference, but even better.

                #9
                Originally posted by Arboh View Post
                Check this out... "Special design for mid-motor e-bikes"? I've asked ....What makes it special?
                https://www.amazon.com/KMC-Chain-2X1...s=e-bike+chain
                Stronger pins, better heat treat, and good coatings. See page 20, here:
                http://kmcchain.org/cms/media/booklet16EN.pdf
                Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

                Comment


                  #10
                  Good to see the ebike chain becoming more available, when it came out I couldn't find a place to get any. Now it seems to be on Amazon, so easy.
                  Last edited by Alan B; 08-05-2016, 08:42 AM.
                  Alan B

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                    #11
                    Thanks JPLabs. Great info.

                    Comment


                      #12
                      I have lost several 10 speed chains using a 3000 watt motor but only one (SRAM) using the BBSHD. My opinion is that KMC chains are stronger than SRAM. BTW: All my chain breaks came in the middle of the chain, not the quick link. I mainly ride fat bikes so my chainlines are terrible, especially on the 42 tooth cog.
                      I did bend the 42 tooth cog on the Sunrace alloy 11-42 with the BBSHD. I replaced it with the steel Sunrace 11-42 and have had no problems since.

                      Comment


                        #13
                        I'm just glad I'm not the only one breaking chains! In just a few months of hard MTB riding with the 1000w BBSHD and a mighty mini chainring, I've mananged to break 2 chains, cracked the small 11t cog and bent a few of the midlle-upper cogs on my 10 speed cassette...and all that with a gear sensor! I also demolished a Shimano XT derailleur but that was due to blunt force trauma. The BBSHD is so powerful, constant gear shifting in steep, hilly terrain can be challenging at times and too much torque in the wrong gear at slower speeds can lead to catastrophic chain and sprocket failure.

                        Comment


                          #14
                          To avoid breaking chains
                          1. Align your derailleur hanger. Most are way out of alignment
                          Park Tool DAG-2
                          https://www.universalcycles.com/shop...s.php?id=17693
                          2. Start out in a low gear so there are more teeth making contact with chain.
                          3. Do not shift under power (both throttle and PAS)
                          4. Be smooth with the throttle when starting from a stop. (NO WHEELIES)
                          5. Keep the chain clean and oiled. (smoother shifting)

                          I converted my Cyclone to a cheesy 8 speed Shimano drive train and have had zero problems (so far) with the 8 speed chain running 3400 watts. The side plates on a 8-9 speed chain are almost 24% thicker than those on a 10 speed chain. So there is a lot more engagement of the roller pins. This does not have anything to do with chain wear "stretch" but makes the 8-9 speed chains less likely to snap under extreme e-bike power. This however is not viable for the BBSHD because the largest 8 speed cog you can buy is 34 tooth. I need the 42t for climbing.

                          Extreme high power users (Cyclone, LightningRods 3000) speed their crank speed up to 180-225 rpm through gearing. Then they only use 7 cogs out of the 10 in the rear cassette. They don't use anything smaller than 18 tooth cog in the rear. This gives much more chain engagement and is much easier on chains. Of course, it is impossible to add any human input to the cranks at 200 rpm.

                          Comment


                            #15
                            Hi, there are many speed chain but I am still confused to take speed chain anyone can tell me about it

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