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Just finished my first build! Chain line, Pedal Assist, and setup questions.

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  • Just finished my first build! Chain line, Pedal Assist, and setup questions.

    This has been quite the learning month. I did as much research as I could, not understanding lot's of what people were talking about, and pulled the trigger about 3 weeks ago by ordering a Anniversary BBS02 kit ($1100 with taxes,shipping and upgrades) and buying a 2017 Giant 29er Fathom ($720 on sale, $900 by the time I walked out the door). I probably would have bought a Lunacycle put together bike, but I was afraid of not getting the sizing right, as i have long legs and a short torso, and most Lunacycle MTN bikes only go up to 19". When parts arrived I joined a local "Bike Church" to put it all together. Of course once I got it apart I discovered what a bottom bracket was and how my motor would not fit. I could have installed the motor on any of the 100's of bikes surrounding me, but not the one I'd just purchased.

    After a few days of confused sulking I decided to put the motor on my 24 year old Giant ATX 770. It probably took me another 5 hours to figure out some of the little details and get it all working, though I still have a few problems.

    A) My shifter and the lunacycle brakes simply don't fit together because of the thickness of my shifter, so I have my brake tilted upwards which does not give me easy access. This gets SCARY when I'm trying to stop when going 30 MPH and I don't even have disc brakes! I've tried every configuration I can think of, but it's still not right. I'm not sure what advice might help me here, but I thought I'd mention it.

    B) Now I have a MUCH better idea of chain line and offset and how important it is. The 2017 Giant I bought had a 36 on the rear cluster, so I got the 48 tooth crank with my Lunacycle kit. Of course my old ATX 770 has a much different rear cassette (13 to 30) and I can't access the largest 2 sprockets because of the terrible chain line. So I'm stuck with about 3-4 gears, most of them small, fast, and which are making my motor run HOT! What I would like is to be able to use pedal assist, not be pedaling at 80 to 100 rpm ( 40-60 would be great), and not overtaxing my motor to the point where it runs hot. It seems that if I use the smallest gears I have access to, then I'm pedaling like a mad man to have any effect (lower the amount that the motor is working). I LIKE having some resistance when I'm pedaling, but the motor, of course, does not. One question is: is there a way to configure the PA so that I can work a bit more but at 40-60 rpm and not burn the motor out?

    C) My old crankset had a 46 on it, so the 48 should work fine with my setup. Yesterday I went for a ride and lost my chain 4 times! 2 of those times were my fault for trying to use a gear I can't yet access, but the other 2 times were simply when I hit bumps. I would like to take this bike off-road, so this worries me. Since my chain line is poor I am considering buying a new crank, and trying to rearrange the gears on my rear cassette. I could use some advice here.

    This has been quite the long road, as I knew very little bicycle mechanics until recently. Though I'm sad that I couldn't install the motor on my new mountain bike, which is what I really wanted, it is pretty cool that my 1993 ATX has yet another life in it. I commuted on it back in the 90's and used it in a couple of triathalons. Then I rode it across the US and twice across Mexico. I stopped serious biking about 15 years ago due to injuries, so it had become my cruiser with ape hangers, and I even took it to Burning Man. Now it is my Electric Green Giant, out on the prowl yet again, aiding me in my injured body to enjoy the outdoors yet again!
    Thanks,
    Todd.
    Brake placement problem Chain line Chainl ine

  • #2
    You need to move either the throttle or shifter to LH - you can’t have all 3 - Throttle + Shifter + Brake on one bar end. Personally, I usually move the shifter (yeah, most work upside down) or use the original 3 spd “front” shifter on LH if I rework the cassette cluster to 3 speeds only? See link below...

    Which brings us to chain line - stock ring doesn't have aggressive teeth and the chain line could stand to be moved inward a bit more for many frames. Lekkie 42T would be a great upgrade, IMO. Not only would the extra 4mm inward offset help chain line to the rear granny but the more aggressive teeth profile also helps prevent chain hop.

    Also reworking rear cassette clusters can often help improve chain lines and maybe use 3-5 widely spaced gears rather than numerous narrow (human) increments designed with leg power in mind.

    Here ya go for more info - https://electricbike.com/forum/forum...-drive-systems

    Comment


    • #3
      What about changing that throttle for a half-twist grip type?

      You will have more room then and things will fit better.

      Comment


      • #4
        Ok, I will try your suggestions!

        Comment


        • #5
          Actually I'm a bit confused. Will the Lekkie 42 bring the chain closer or farther from the bike? I need the chain to be closer in order to get to the larger cogs on the rear cassette, but there isn't room to move closer because of the battery. I had to mount the battery where it is because the holes on the other tube were in the wrong place.

          Comment


          • ykick
            ykick commented
            Editing a comment
            42T Lekkie moves "inward" another 4mm from where the stock ring sits. Which looks very close to your battery so if you go that route you may need to relocate the battery pack cradle position? Did you re-drill any mounting holes in the cradle? That's what many folks do to better catch their particular frame threaded inserts.

            It's not too hard to install threaded inserts on bike frames either. Google "rivnuts" or check with LBS (local bike shop) for that info.

        • #6
          Ok, I looked at the rivnut route when I originally installed the battery because I didn't have holes that would work on the downtube where I wanted to install it. Looking at it now, it seems I'd have to install the battery pretty high on the downtube in order to accommodate the Lekkie, which will move the balance point of the bike up. Is my bike just odd in this way? Luckily it's big enough to work.

          Also, 4mm doesn't seem like that much considering I have 2 gears I cant use. I must have lost my chain 10 times yesterday when I tried to go mountain biking. I realize that the more aggressive teeth will help, but the chain line looks terrible on those big cogs. Will 4mm be enough or should I be looking at other options? I might even be able to keep my battery in the same spot if it only moves 4mm. I saw the below image elsewhere on your website. I was confused because although it has a lunacycle crank, it does not have the lunacycle 48 that came with my kit. So if the lekkie 42 is listed as having a 21mm offset, does this mean that the Lunacycle 48 has a 17mm offset? Thanks!

          Comment


          • ykick
            ykick commented
            Editing a comment
            42T Lekkie is smaller so that can help overcome the largest rear granny gear if it’s still a problem. I doubt it will be due to the more aggressive teeth and moving inward 4mm.

            Those chain rings you posted are for BBSHD NOT BBS02. Much more limited choices for BBS02.

            DIY eBikes sometimes require compromises. Also accepting that something we might "think" is a big deal may not be such a big problem, in practical application.

        • #7
          I appreciate your comments, but I'm not sure I understand what you are saying when you say,
          "42T Lekkie is smaller so that can help overcome the largest rear granny gear if it’s still a problem. I doubt it will be due to the more aggressive teeth and moving inward 4mm."
          Are you saying that just because it is smaller that I won't loose my chain? That doesn't make sense to me at the moment. If I try to use the largest 2 or 3 cogs, my chain line is terribly angled, and that is when I lose the chain. Moving the crank inward toward the bike would make the chain line a bit straighter. Isn't that what I'm supposed to be trying to do? Oh wait, I think I might be understanding now on my 3rd reading. I'm now realizing that if I read your message with a comma after BE it completely changes the meaning. Duh! Am I reading it accurately now?

          I did realize that the picture I was using was for BBSHD cranks but I had no idea whether or not there were differences. So what then are my options for the BBS02? I made several buying choices without a complete understanding of what I was doing and those choices have caused problems with my build, especially the one where I bought a motor and a bike and they don't fit together, so I'm really wanting to understand my intent and options as I try to rectify the problems with my current build. A 4mm difference just doesn't seem that big. Thank you!

          Comment


          • ykick
            ykick commented
            Editing a comment
            All I meant is that by using a smaller front ring you may not need the larger gear(s) on the back. The lowered ratio, coupled with more aggressive teeth and 4mm inward movement will probably cure most practical chain line issues.

            If you need or feel compelled to correct chain line further, check the link pasted several comments up. Merely move the larger gears out away from the rear hub and use fewer gears in the first place.

            You can view all of the Luna chain ring offerings which fit BBS02 here - https://lunacycle.com/bbs02-parts/

        • #8
          As ykick stated, there aren't many options for the BBS02. Your best bet is the Lekkie with more aggressive teeth and a little offset. Some like ykick also realign their gears to a more central choice of three gears. ykick has posted a how to on this.

          Comment


          • #9
            There is one obvious solution that solves all your problems and it`s one i done to my own BBS 02 build.

            Dump that cassette, derailleur etc and get yourself an IGH. Alfine 8, Sturmey Archer or whatever.

            no more messing around with chain lines, adjustments, derailleurs etc, etc

            Or if you`re intent on keeping your existing setup reduce the number of cogs on the cassette, the BBS02 doesnt need many, too much torque.
            7 is more than enough, plus a KMC eBike chain

            Comment


            • #10
              Ok, I ordered the 42T Lekkie and will give that a try. I'm hoping Bike Church has rivnuts because I think I will need them. Once I get that figured out I'll see if I need to realign the gears. I didn't know what an IGH was, but after a little research that looks like a fun option as well. Thanks everyone! I'll keep you updated on how it goes.

              Comment


              • max_volt
                max_volt commented
                Editing a comment
                I was wondering about the new bike. Did you try to return it? Was the bottom bracket too wide and could be ground down or was it pressed fit and needed an adapter?

            • #11
              If you do install an 3 speed IGH, look at a Sturmey Archer. Their thumb shifter will ovelap a brake lever mount and you can have the shifter brake and throttle on the right.

              Comment


              • #12
                You mentioned chain length. Sure, it's long enough, but is it too long?When mine was 4 links too long I had more chain drops when on small rear cogs, since tension was too low. Shorten your chain to minimum proper length for the gears you actually use, and you raise chain tension, which helps keep the chain on.
                Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

                Comment


                • #13
                  OK, I got the leakiest 42 and installed it, but it only has about a 1 mm clearance with the battery so I need to move the shark pack up but don't have proper holes on my steel frame. They have some rivnuts but only for aluminum and I'm guessing I need to steal to hold all that weight :-(

                  I did not even try to return the new bike because I had ridden it in the dirt. It had a self extracting crank and from what I read there was no way to make it fit

                  Comment


                  • max_volt
                    max_volt commented
                    Editing a comment
                    Self extracting sounds like it would fix itself. But do you know the exact PFxx or BBxx model of the bottom bracket?
                    leakiest 42 that made me laugh sorry

                  • Peter Halt
                    Peter Halt commented
                    Editing a comment
                    aluminum rivnuts hold the the sharkpack fine on steel and aluminum frames.

                • #14
                  The bottom bracket on the Gaint Fathom 29er 2 is an FSA, pressfit. I wasn't sure of the exact measurement but it was around 90 mm.
                  https://www.giant-bicycles.com/us/fathom-29-2
                  I got the BBS02 Anniversary kit from Luna Cycle, which fits 68mm and 73mm bikes. From what I read elsewhere there is no way to make them fit together.

                  BTW I got the Lekkie on today and shifting is way better! Now I can also run the engine spinning faster so i won't burn it out. I ended up moving the battery but drilling a hole in the aluminum plate of the Shark pack, but now both screws are towards the bottom of the battery so I will need to do something for the top of the battery at some point. I just zip tied it for now. :^)

                  Comment


                  • ykick
                    ykick commented
                    Editing a comment
                    My pack/cradle fits with fasteners down low. As long as one hole is in the aluminum plate it really isn't a big deal if the top of the cradle isn't bolted down.

                    Although riding rough terrain and/or tossing the bike around many people add simple web strap to secure the battery to the frame. Remember threaded inserts were only intended to carry 1-2lb water bottle. Not 7-8lb battery pack.

                    Glad the chain ring is working better for you.

                • #15
                  angle grinder
                  Click image for larger version  Name:	img_8700.jpg?w=768&h=1024.jpg Views:	2 Size:	475.8 KB ID:	45382
                  Last edited by max_volt; 19 hours ago.

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