Announcement

Collapse
No announcement yet.

Replacing a 8 gear gear with Nexus 3 on a BBSHD commuter

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Replacing a 8 gear gear with Nexus 3 on a BBSHD commuter

    Hello,
    Is the Nexus 3 a good option for a commuting bike with a BBSHD?
    With the current setup it is difficult to changegears and I always stay in 5th gear so I figuerd I just change to a Nexus 3 and get rid of some maintenance.
    Any thoughts on this modification?

    #2
    Greetings, and welcome to the forum.

    IMHO the Nexus 3-speed hub works well and has, depending on the bike frame dimensions, a slightly easier to hit chain line when combined with the BBSHD. I initially built up my guest bike using this hub. In second gear it's also very efficient.

    A downside may be, depending on the bike's wheel size, having a low enough first gear ratio for your needs (health, terrain, etc.). With the BBSHD, you're still likely going to be limited to a minimum of 40 teeth on the front chain ring. A 40 tooth chain ring combined with the biggest readily available 24 tooth rear cog and you end up with a rather high but narrow ratio range, not suited for steep long hills for example.

    I ended up updating my guest bike to an Alfine 8-speed because of the above limitation. For my terrain, a wider gear range is necessary.

    You wrote, "With the current setup it is difficult to change gears" - do you currently have an internal hub or perhaps a derailleur? What's the difficulty you're encountering?
    Last edited by ncmired; 08-29-2022, 08:35 AM.

    Comment


      #3
      I had a Nexus 3 with a BBSHD too and did have some concerns about its durability. Range was a big limitation and problem for me. I did change rear cogs and that helped but not enough for me. I'm not a lightweight person so I need some low gears to climb a hill. It did start making some not good sounding sounds so since I wasn't happy with it anyway I just converted back to a 10 speed.

      If you always stay in the same gear how about single speed? Use one of the online gear calculators and figure out what your 5th gear is and see if that could be done with a single.

      I too would like to hear more about your gear changing issues.

      Comment


        #4
        Hello and thanks for the responses.
        I have a derailleur and when chaning gears there is a very high load on the chain so i feel that it is hurting the gears and chain. I dont have a gear change device that disconnet the power while shifting.
        I am also a quite heavy guy and I use the bike for commuting and there are not too many steep hills from where I live to office but there are a couple so 3 gears I think would be great
        I will definatly consider a one-gear set-up, I like low maintenance and robust solutions so maybe that's the way to go, but not given up the Nexus 3 just yet..
        I would need it with disc break and I am a bit concerned how a new wheel with Nexus3 and disc will fit my bike.
        Is this resonable standard or are there anything I need to check before purchase?
        Again thanks for the responses!

        Comment


          #5
          I think the Nexus 3 only comes in 135mm width so that is the first thing you have to check. You can't use spacers if you are close because of the way the shift cable connects, its got a very narrow window of adjustment. It does have a disc brake option which is Shimano's center lock system. You can buy adapters to go from centerlock to the more common 6 hole rotor if you don't want to use a centerlock rotor. The locknut for the centerlock system uses the same tool as the locknut on Shimano cassettes.

          Comment


            #6
            As 73Eldo said, the Nexus is available with a disc brake rotor mount, using the Shimano Centerlock standard. Your bike frame has to have standard dropouts, spaced 135mm apart. If your bike is older this is probably the case, but you'll need to verify.

            But I need to ask, do you have the motor's throttle on while trying to shift? If so, stop that practice - just pedal, and with a light force during the shift sequence. Having the motor engaged while shifting is very hard on your bike's drivetrain, and will quickly ruin internal geared hubs like the Nexus 3-speed.
            Last edited by ncmired; 08-29-2022, 01:05 PM.

            Comment


              #7
              Ya he makes a good point about if you are having shifting issues now they could be worse with something like a Nexus.

              Comment


                #8
                Originally posted by turbo101 View Post
                Hello,
                Is the Nexus 3 a good option for a commuting bike with a BBSHD?
                With the current setup it is difficult to changegears and I always stay in 5th gear so I figuerd I just change to a Nexus 3 and get rid of some maintenance.
                Any thoughts on this modification?
                Staying in one gear makes me cringe a bit, especially if heavy loads and/or high acceleration

                BBSHD isn't happy producing lots of power at low pedal speeds, much happier the higher you can take it comfortably

                Comment


                  #9
                  It would be cheaper to get a shift sensor, so the motor cuts out when shifting, than to put a new hub on.

                  Comment


                    #10
                    This is a nice offset rear sprocket that I found to help on chain line with the BBSHD.


                    They shipped via fedex within 24 hours

                    Comment


                      #11
                      Hello,
                      I am not using throttle while shifting but the power from the pedaling gives tension and stress anough I feel.
                      Perhaps the shift sensor is the way to go here - and also I cannot run on the highest (smallest) rear gear due to the chain offset so I need a replacment front sprocket.
                      Any suggestion on a good gear?

                      I will get the shift sensor and keep the gurrent rear hub.
                      I also tried to pedal faster and I noticed the engin felt better and also noticed reduced power draining - thanks for the inouts and tips!
                      Being in europa not all offset sprockets are available but perhaps you can recommend a good offset?
                      Gear 1-8 är OK but 9th gives offset isssues..
                      Is this an alternative?
                      https://www.amazon.se/FACULX-kedjeri...445358305&th=1

                      BBSHD original seems to have 19mm offset, am I thinking wrong, should my offset be less to better support the tightmost rear gear?
                      (Sorry for noob questions)
                      Last edited by turbo101; 09-13-2022, 09:12 AM.

                      Comment


                      • AZguy
                        AZguy commented
                        Editing a comment
                        If you are trying to push the chain ring (front cog) outward, if it's not a lot it can be shimmed

                        If it's more than a little maybe try a 130BCD ring adapter - I get a good chain line with those

                      #12
                      I put an Alfine 8 on in order to have enough range. I'm with AZguy about gearing being important for any hills. I don't use a shift sensor either. I just BACK PEDAL slightly which turns off the motor and then shift as I begin pedaling again. It works well.

                      Comment


                        #13
                        Anyone that can link a 130BCD ring adapter - I think this would be the best idea :)

                        Comment


                          #14
                          Try this one:
                          Distributors and builders of high power electric bikes and trail bikes plus parts

                          Comment


                            #15
                            I have an 8 speed urban bike. Try this mod. It's new so feedback will be appreciated. But it's working for me. The chainguide is probably needed.
                            https://electricbike.com/forum/forum...ed-a-freewheel

                            2 other 8 speed mods are a Rapid Rise (low normal) derailer, and a twist shifter (hard to find for RR, non existent in US)
                            Last edited by Retrorockit; 09-28-2022, 07:30 AM.

                            Comment

                            Working...
                            X