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Suggestions for widest ratio gearing cost effectively?

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    Suggestions for widest ratio gearing cost effectively?

    Hi all! I got a Luna Wolf Alite back in April with the Ludicrous motor and I love it! I commute to work 14 miles one way several times a week. I have a basket, a backpack, and a rear wheel rack for regular cargo space and a kid trailer for taking my boy out on errands on the weekend. Before my ebike I'd never commuted or owned my own bike so this is an awesome introduction to the community! Unfortunately this also means that I'm a big newb and I could use a lot of help for my current ebike undertaking.

    The Luna Wolf came with a 42t chainring and a 9 speed 11-34 shimano alivio cassette/gear set. What I want to do is extend both the higher AND lower gearing because my area is very hilly, I want to be able to haul lots of cargo, and I want to be able to assist my motor with pedaling even at high road speeds to help extend battery life and make the bike even more commuter friendly. My thought is to change the chainring to a 48t and switch the cassette to a 9 speed 11-46t or 11-50t. The current setup affords me a 1.24-3.82 gear ratio. The 48t with 11-46t could manage a 1.04-4.36 and the 11-50t would drop it further to 0.96-4.36. I doubt the current RD would manage a 11-50t cassette even with a hanger extender though and 11-46t would be most likely be pushing it (although I can't even figure out if my current RD is a medium or long cage... I'm such a newb). Can anyone weigh in on the most cost effective way to extend my gear ratio range? Bonus super awesome points for you if the setup you suggestion is cost effective AND compatible with something like the SRAM DD3 IGH 3 SPEED HUB WITH SHIFTER that lunacycle is currently offering. (That would make the range even bigger right?)

    #2
    I've got an 11sp derailleur presently with 11-46t sunrace cassette with all-steel cogs and it is perfect for my use which covers very steep off-road and flat smooth surface. I've run 11-42t which is enough but prefer the 11-46t.

    I've never seen 11-46t in 9sp...

    Comment


      #3
      I found a 9 speed 11-46t cassette here-
      https://smile.amazon.com/dp/B07J5V48...v_ov_lig_dp_it "HATOLY 9 Speed Cassette 11-46T Wide Ratio Freewheel Mountain Bike MTB Bicycle Cassette Flywheel Sprocket Compatible with Shimano"

      and a 9speed 11-50t cassette here https://smile.amazon.com/dp/B07FYBXX...v_ov_lig_dp_it "
      JHKJ 9-Speed/Card Tape Cassette"

      I'm not sure if I could use either with the RD the bike came with though even with a derailleur hanger extender.

      Comment


        #4
        It doesn't exist yet. But I think a 39T 50T 2 speed front derailer would be ideal. 2 chainlines. One for climbing and on for road work. The derailers 2ndary function as a chain guide doesn't hurt either. A frame mounted shifter would work since you're not likely to need both ranges at once. Everyone seems obsessed with 1x setups. I'm running 50x11 on 26x2.0 tires and it's a nice top gear. With bigger tires 48 should be OK. But for 8-9 speed I think a front derailler makes sense.

        This is all your fault. I just found a Sunrace 11-40T 8 speed casette. 11-13-15-18-22-28-34-40t. I'm always double shifting up from my 28t launch gear 28-24-21 anyway. I have some unfinished business getting a Rapid Rise/ Gripshift setup working so I can dump 5-6 gears at a stop light while standing still.
        Last edited by Retrorockit; 12-01-2018, 11:36 AM.

        Comment


          #5
          As you know, with the 3-speed/freewheel hubs (SRAM or Sturmey Archer) you get that strong 1:1 2nd gear for "most of the time" riding, with approx 2 more gears lower and higher than whatever cassette you come up with via the 1st and 3rd gear. I'd be tempted to go for the conservative 11-40 and see if it gave you enough low gear (with the 42 Eclipse).

          I'm sitting here staring at a Luna Eclipse 42 gear piggy-backed on a 48 gear - maybe that could be made to work, although the spider would have to be spaced farther out and then might interfere with the crank arm. And, with the wide-narrow teeth, would probably resist shifting.
          Last edited by ncmired; 12-01-2018, 01:43 PM.

          Comment


            #6
            SRAM had a 3 speed IGH with casette called Dual Drive I think. Since it had an over/under gearing it came with a 32 or 38 chainring. Cannondale made some hybrids with it. 42T Luna should work fine with that.
            WideNarrow would be a mess shifting. The chain has to land odd/eve teeth every time.
            I guess they're calling it DD3 now.

            Be aware that there is a shifter housing hanging off the end of the axle. I'm not sure how rugged it is. Also i don't see a QR working with that setup either.
            Here's a photo of one. Dual drive,Headshock. If it had disc brakes it would be perfect for a BBSHD swap
            https://www.bicyclebluebook.com/sear....aspx?id=30140
            One shifter runs the whole thing. Room for a throttle.
            Guess who has it in their catalog?
            Distributors and builders of high power electric bikes and trail bikes plus parts
            Last edited by Retrorockit; 12-01-2018, 05:17 PM.

            Comment


              #7
              Another approach would be the Bafang 130mm spider adapter with this ramped and pinned 50T chainring (I've had this on my BBSHD) and their 38/39T version hollowed out and hung off the back with bolts and spacers using s front derailler. You could probably use a 130BCD double crank as a jig for drilling and installing spacers to build this.
              https://www.amazon.com/USA-Made-5-Bo...ainring+130bcd
              A drill press is all it would take to make the holes. Some flat head machine screws on the outside would keep the screws from moving around in the gear. Maybe thread the holes into the small gear for clearance on the back side. With a lathe you could get fancy and put a shoulder on the spacers. Leave a few bare threads sticking out the back. the last couple of threads are weaker and won't hold as well. If there's room for nuts on the back that would be best though.
              edit
              Looking at what Luna has done it seems 42t is the smallest that will fit around the Bafang gear case. Un fortunaely theres a gap in gear sizes in shiftable chainrings with 130bcd. The mid/small ring is either 38/39T Then a jump to 48/50/52t. I don't think the small gear needs the ramps to lift the chain. There are some track 42t 130bcd chainrings for 1x and they seem to be made as a solid disc solid so lots of places to drilll into them.42t is fairly common on 104bcd MTB cranksets. But it would be harder for a DIYer to index them for drilling.
              Last edited by Retrorockit; 12-02-2018, 10:32 PM.

              Comment


                #8
                I've been digging around in my parts bin and found an XT 44T chainring. And I also have a 50t shifter chainring 130bcd that fits the bafang spider. My thinking on this right now is to have a local plastic shop cut a Lexan ring the right thickness with an OD to match the 44T chain recess, and an ID to clear the BBSHD. Glue it all into one piece and reinforce it with bolts wherever there's enough overlapping metal to do so. There is a water jet cutting shop I've been meaning to visit. So metal might be an option also. So I could keep my 50x11 top gear and add a 44x40 low gear with a chainline that will allow me to use it.
                Does anyone know the ID of the Luna 42T chainring assy.?

                Comment


                  #9
                  Originally posted by Retrorockit View Post
                  Does anyone know the ID of the Luna 42T chainring assy.?
                  You mean the Luna Eclipse? If so, its ID is slightly wider than my 150mm caliper, so I'd put it at a slightly fudged 153mm until/unless somebody can come up a closer measurement.

                  Comment


                    #10
                    Thanks for the reply. 153mm=6.023" So that's 6" in my book. If I have the water jet shop cut it they could probably makes 3-4 at once.
                    I've got the 11-40t casette here. I was so excited to find it in 8 speed I just ordered one. It's black, and silver was $10 cheaper but I didn't ask so black it is. My chainrings are black also so I guess it's meant to be.
                    What's a good source for the long derailer hanger/adapter. I see $2 ones from China. And I see Wolf makes one for road bikes. Is there one that people are having good results with?

                    Comment


                      #11
                      I took a ride to my LBS. No not the SoFla bike boutiques in Ft Lauderdale . I rode past about 10 of those. MY LBS which is 20 miles away. Picked up a 42T chainring, and scored an XTR Rapid Rise derailer.
                      So far I have a Bafang 130BCD spider adapter,a 50t "host" chainring, a 44t, or 42t to "piggyback" off of it, and derailer hanger extension in the mail. I think the LBS owner sold me the XTR because there may be some chance of it working with a 40T casette. Maybe "B Screw" length has something to do with it. Actually IDK what a B Screw is. Yet!
                      This thing keeps evolving slowly in my mind. I may skip the glue amd fasteners completely and just have the whole damned thing TIG welded together. Well just the rings and spacer not the adapter!
                      Oh I almost forgot. He had an old black Cannondale Headshock bike there with disc brakes. It's a 700c which bothers me not one bit since 26" wheels with 2.3" tires = 700c diameter anyway. I've run both on my 26" XC Softtail. Might be able to squeeze some 26x2.5"" Hookworms in there on my Rhynolite XT off road wheelset I never use anymore. Even without a motor I have some black Cane Creek Strados 700C disc brake rims that would "make" that bike.
                      Last edited by Retrorockit; 12-07-2018, 10:13 AM.

                      Comment


                        #12
                        Well- welding 7075 aluminum isn't going to happen. BUT it turns out this whole mess could be soldered together on a hot plate. Maybe even with a steel spacer if I get it tinned or plated first.
                        Maybe you can't teach an old dog new tricks. But there just might be some old tricks that can give the CAD/CAM boys a run for their money.

                        Comment


                          #13
                          I spent the afternoon swapping parts. The big casette is going to need the hanger extension, and it turns out the XTR derailer is a short cage model, so I get either the 11-40 casette, OR the 50/42 chainring but not both. The casette will be tried first once I have all the parts. It's just a bolt on mod and will do everything I need. I might give the Wide-Narrow 50t ring a chance and see if it allows me to use all the cogs.
                          I can't complain really. An XTR Low Normal Short Cage dearailer is quite a find for a 1x8 urban bike. I do have a long cage low normal LX derailer on my XC bike. But it makes more sense to leave it there.
                          Last edited by Retrorockit; 12-08-2018, 07:29 AM.

                          Comment


                            #14
                            A little more on the 2x 50/42 BBSHD chainring idea. Surly makes a 50T and a 42T stainless steel 130 BCD ring. Stainless steel can be silver soldered which is AKA silver brazing due to the heat involved, 70.000PSI strength is common. The spacer could be steel. stainless steel or even brass. A friction shifter should be able to shift this. I see it as a range type shift and not a shifter you would be going through the gears with.
                            Last edited by Retrorockit; 12-08-2018, 07:32 AM.

                            Comment


                              #15
                              Here is a speed calculator I found. Just enter tires size and gear teeth and it will show speeds at 90RPM.
                              Calculate cycling speeds in kilometers or miles per hour given cadence, chainring, sprocket, tire and wheel sizes.

                              Low gear in the Sturmey Archer is .75 and high gear is 1.33 so a 36T chainring would model as a 48/36/27 triple crankset. I think I've got it right. Low +33% and mid +33% is what I'm using for that hub.
                              I know engineeres will say I have it backward. If I was calculating torque that would be true. But I'm calculating speed and I believe this is correct. If you disagree use something else and be happy.
                              Last edited by Retrorockit; 12-10-2018, 08:54 PM.

                              Comment


                              • commuter ebikes
                                commuter ebikes commented
                                Editing a comment
                                I would have chosen 90 RPM, also. Thanks for being reasonable here.

                              • Retrorockit
                                Retrorockit commented
                                Editing a comment
                                That was their default RPM. There are cadence, and gear/inch versions there also. BTW 700cx38, 27.5x2.0, and 26 x2.5 all give roughly the same speeds.
                                I've observed the speeds they list in those gears, but it's not sustainable for my 65year old legs. Maybe a mile and I'm done.On some of their other calculators you can choose different cadence.
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