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Chain line really out of wack with 30 tooth mighty mini

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    Chain line really out of wack with 30 tooth mighty mini

    I was a little disappointed when i installed the mighty mini to my full suspension Giant Trance because the chain line was worse than using the raceface with the adapter. After a few weeks of riding I decided to remove a few gears from the rear cassette so I could improve the chain line on the granny gear. I converted my 9 speed cassette into a 7 speed by removing a few gears and adding spacers behind the granny gear. Now I have a much better chainline when using the lower gears. I find that I don't need that many gears anyways when using the motor combined with pedaling.

    #2
    yeah the 30t has no offset...the eclipse has the most offset of all the custom chain rings.

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      #3
      Does anyone know if a standard 7 speed cassette will work with my 9 speed shifters? In this conversion, I started with a 9 speed cassette so the indexing is the same. I don't want to go thru the hassle of customizing a 9 speed cassette the next time I have to replace it. I really do enjoy the wheelie popping torque now.

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        #4
        Hi there, i just ordered the mighty mini for my bbso2 also and was thinking the same thing i have about 15mm i can grind off the bottom bracket to move the whole unit inwards and as im mainly in the forest i very rarely go over 25mph so i to dont need all those gears. In fact of the 10 i have im mainly using the top 4 so i was thinking of moving the whole lot outwards and putting spacers between the cassette and hub. Do you have any problem setting the gears up so that the chain cant go past the granny gear and drop onto the spacer?? I was thinking of some kind of plastic disc

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          #5
          I set the Low limit screw on the derailleur so that i can't shift beyond the granny gear.
          Last edited by ebikerman; 04-08-2016, 06:47 AM.

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            #6
            My advice for those with a really bad chain line: DO NOT buy the 30 tooth mighty mini, it is a few mm worse than using an adapter with Race face. I'm really unhappy with my shifting and I may have to order the 42 tooth Bling Ring and perhaps try grinding down the bottom bracket on the drive side by 10mm too. Just a bit frustrated at having to waste more money on this bike to try to get it perfect.

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              #7
              That's a good observation.

              The smaller the cog, the further to the right (drive side) it has to be to clear the drive unit. And the wider the rear dropout, relative to the bottom bracket, the better this works. My bike has a 197mm rear dropout width and a 100 mm BB, so the 30T Mighty Mini lines up well.

              A narrower dropout places the rear cassette further inboard, so needs more inboard offset at the front.

              Spending money and effort on a project bike to make it perfect is no waste of money, it's half the fun!:p
              Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

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                #8
                I'm in the same boat on my Norco Bigfoot 6.3 BBSHD. With the mighty mini the chain line is pretty bad. In my case pushing 1000watts through something like the Nuvinci N330 or N380 might break the CVT? Click image for larger version

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                1. How much is too much in terms of the chain line whackyness?
                2. Is there anything I can do besides changing chainrings or going for heavy CVT Nuvinci N171?
                3. Is there some special cassette with reduced spacing?


                Although the chain line is pretty bad in the 'granny gear', considering the tooth count of the mighty mini, unless you're going up a vertical wall I would think the granny gear wouldn't get used as much? Would this make all the other gears have more 'torque'? Luckily when I ordered the Mighty Mini chainring I also ordered the Bling Ring which seems to have a much better chainline. Click image for larger version

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                Nuvichi N380
                https://electricbike-blog.com/2016/0...s-of-them-all/
                Attached Files
                The Nuvinci Planetary CVT allows for a bicycle to have an unlimited number of gears within a certain 'range'. The only problem is that all of the Nuvinci CVTs that are currently on the market are only warrantied with a 250 watt motor, or in the case of the N380 350 watts (as long as it's…

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                  #9
                  That does look like too much chain zigzag with the Mini! Even if it shifts OK, the chain will be pretty highly stressed. Chain wear is faster the more it has to bend sideways while under power.

                  Some folks have removed sprockets from the rear cassette and spaced the cassette outwards, for fewer gears with better chain line. Same shifter, just set the high-limit screw so you can't over-shift past the big cog. Even 5 gears would seem plenty for a BBSHD.

                  Ebikerman did this, he even mentioned it in the OP of this thread.
                  Last edited by JPLabs; 04-10-2016, 07:30 PM.
                  Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

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                    #10
                    Originally posted by JPLabs View Post
                    That does look like too much chain zigzag with the Mini! Even if it shifts OK, the chain will be pretty highly stressed. Chain wear is faster the more it has to bend sideways while under power.

                    Some folks have removed sprockets from the rear cassette and spaced the cassette outwards, for fewer gears with better chain line. Same shifter, just set the high-limit screw so you can't over-shift past the big cog. Even 5 gears would seem plenty for a BBSHD.

                    Ah thats a good idea. The cassette I have on now is a 9 speed, you're suggesting to take out say 4 of the smallest cogs (since speed isn't really something I need on singletrack) and space outwards to improve the chainline?
                    I guess these are the spacers I'd have get
                    http://www.jensonusa.com/!JNWNjsZRIo...assette-Spacer

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                      #11
                      Maybe not 4, I think you could be limited by how far out your derailleur will adjust to clear bigger gears at the outside (turn B- tension screw in). You will need to look at that.


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

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                        #12
                        Great pictures of your chain line, mine used to look like that too until I removed 2 gears and shifted the cassette over using spacers. I tried removing 4 gears, but the granny gear ended up hitting the derailleur and when I removed 3 gears, I didn't like the big jump in some of the gears so 7 speeds is comfortable for me. I still wasn't happy with the shifting so today I decided to cut off 5mm from the drive side bottom bracket with my grinder to see if that had an effect. It actually shifted a bit better with less ghost shifting from the short test ride. I will go for a longer ride tomorrow. Even after grinding 5mm from the bottom bracket, the chain line was still only straight near the highest gears so I may end up ordering the bling ring. Do you have enough torque with the 42 tooth for climbing extremely steep hills? I only have a 34 tooth on my granny gear, but it can climb hills steeper than I can handle. Under full throttle with the 34 tooth, I can't pedal fast enough to keep up with the motor so I just hang on and focus on navigating up the steep hill.

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                          #13
                          Yeah 7 speed seems like the way to go. Although I was wondering to test it out I could just set the limiting screw instead of taking off the gears (at first) then take them off (weight weenie style) later.

                          I only just finished my build last night, I've yet to test it yet. I'm in Toronto so closest thing around is Don Valley which I don't think has many steep hills, but I will find something I'm sure. My granny gear is 36T I think.

                          My idea was to switch to the mighty mini for the winter (snow) and if I'm going to particularly hilly places. Having said that for all I know the 42T bling ring might not be suited for single-track at all (especially since I have the awesome mighty mini) and It might get donated (bling ring) to another build more suited to road bike / longer trips

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                            #14
                            I currently have the 42t bling ring and i havnt found a hill it wont pull up. Even off road the back wheel will spin up before the motor bogs down. Im only trying the mighty mini to see the difference. I shaved my bottom bracket as far as possible and now have a great chainline with the bling ring. So im hoping by removing 2-3 gears the mighty mini will line up.

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                              #15
                              A simple solution


                              A $5 chain idler tensioner pulley in this position acts as an effective chain guide. Won't bounce up or move too much left or right. The chainline before the pulley was bad enough that it immediately derails in first gear, but with the pulley there it is basically impossible. It also is impossible to fall off when the ebike is doing big jumps, very useful for a true offroad machine.

                              You would want it close to the chainring. The smaller the pulley, the closer to the chainring. Multiple brackets can get a pulley into this position and pulleys come in different sizes and colors.

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