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    Tips for new Ludicrous buyers

    The purpose of this post is to help other new Ludicrous riders with Lessons Learned from my experience learning to ride the bike without failing it.

    See my update regarding programming settings that reduce failures at the bottom.


    When I bought a bike with Ludicrous, I had a lot of experience riding bikes and some experience with a more conventionally-powered e-bike. I also knew Ludicrous is only intended for experienced e-bike riders. Even with this background, I experienced a long learning curve including failing several parts. It's advisable to gain experience with a lower-powered motor before buying Ludicrous. However, the cost associated with buying twice is out of budget for many of us. This article is intended as a summary intro-to-Ludicrous to help others save time and money by avoiding the pitfalls that I dealt with due to my lack of experience. One potential alternative to buying twice could be to buy the programming cable from Luna and set your Ludicrous motor to the street-legal power level until you gain experience with it.

    The chainring and cogs in particular can be described as both delicate and strong and reliable. They will fail quickly if exposed to unusual stresses but will last forever as long as the rider is aware of the risks and how to mitigate them.

    The Golden Rule of riding Ludicrous is to use all the gears and stay in the lowest gear you practically can at all times. This essentially prevents at least two failure modes: Melting the nylon gear in the BBSHD, and stripping the rear cogs, mostly the smallest cog (highest gear). Even with an awareness of this, I heated up the motor to moderately risky temperatures on my first ride and subsequently stripped the rear cogs not once but twice before I learned the criticality of staying in the lowest practical gear.

    The primary reason I stripped my smallest cog twice is it was subject to too much torque. A small cog made out of the standard material is no match for 2500 watts of power at low to moderate speeds. At any given power level, a lower gear puts less stress on the motor and cogs. With throttle only, never use the highest gear unless your speed is at least 25 MPH. Do not use the second-highest-gear unless your speed is at least 20 MPH. With PAS, these minimum speeds will need to be lower in order to keep up with pedaling but be mindful of this at all times. In other words, use lower gears with the throttle than you do with PAS at any given speed. I have been mitigating the risk of overtorquing the motor and cogs by using PAS 3 as opposed to 4 and 5. With the stock profile, the PAS power doesn't cut back quickly enough when torque is lessened to prevent shifting under load, even with the installed gear sensor (highly recommended). The motor power is present even with minimal torque when pedaling at PAS 4 and 5. With Ludicrous, PAS 3 is plenty of power. If you choose to use PAS 4 or 5, approach with caution and learn to use 3 prior to 4 prior to 5. I recently found out from Luna that their Limitless profiles should be a resolution to this because they're programmed to cut the torque as quickly as possible while the stock Bafang setting waits a short time before cutting torque. I will be ordering the programming cable and switching to a Limitless profile.

    If your chain skips even once, or you hear a hard shift, immediately downshift or cut back on power until you can understand what caused it and prevent recurrence. With the power of Ludicrous, it doesn't take much skipping before your cogs require replacement. At a certain point, skipping will cause a secondary failure of your front chainring. Before I understood that skipping was a serious issue, it caused a tooth to break off my front chainring. A replacement chainring cost me $90 plus the shims required to accommodate the style of chainring Luna sells as a spare part. Nothing was wrong with the chainring. The sudden jolts of speed under load from the chain skipping over the stripped smallest cog caused the failure. The bike was inoperable until the replacement chainring and cogs arrived. Not to worry - this shouldn't cause you to use less power or speed than you otherwise would. After the learning curve, Ludicrous will provide as much acceleration and speed as you expect it to. Approach Ludicrous slowly and with caution and ramp up the amount of power you use as you gain experience with staying in the lowest practical gear and avoiding hard shifting. Also, I recently replaced my stock Shimano cassette with a stronger steel Sunrace cassette. Initial indications are that the extra strength is helping avoid stripping.

    It's well-documented that the nylon gear in the BBSHD will fail at high temperatures. The guidelines developed by Karl Gesslein say to stop riding and let it cool at 140F. This is a controller side temperature. I have not opened my BBSHD to add a thermometer but based on measuring the outside with a laser thermometer the motor side always appears to be warmer than the controller side. When the far end face of the motor measures 140F, I can hold my fingers on it for about 2 seconds before feeling the uncontrollable urge to pull my hand away. When it measures 130F, I can hold my fingers on it for 4 seconds. 120F is the upper limit of being able to hold my fingers on it indefinitely. Bottom line, if you feel the far side of your motor and cannot hold your fingers on it for 2 seconds, it's probably time to let it cool or use minimal power.

    Good news is if you proactively stay in the lowest gear you can to maintain your speed, it's rare for the BBSHD to get too hot. The common mistake that causes nylon gear failure is using higher gears than necessary. Per Luna, "the motor likes to spin fast." The motor can put out a lot of power yet remain cool if it's spinning fast. It can put out the same amount of power but heat up quickly if it's in a higher gear.

    The shifter cable will probably stretch early on causing gear skipping and shifting that is not smooth. This is normal for a new shifter cable. I was unaware of this until after my chainring failure. It was a major contributing factor. For the first few hundred miles, periodically check the derailleur positioning to make sure it's in alignment with each gear. Check immediately any time your chain skips and adjust if needed.

    Know that riding with Ludicrous will wear heavily on your brake pads. Have spare pads on hand.

    This may sound like a lot of information but it's nothing to worry about as long as you have the time to learn. Bottom line, always use the lowest practical gear and try not to shift under load. Buy the optional gear sensor. It won't be long before you learn what to watch out for and have many years of speedy Ludicrous rides to look forward to.

    **UPDATE** 2/25/20: I discovered after ordering the programming cable and pretty much adopting "Karl's Special Sauce" settings (aqua numbers) from the following page that I'm no longer (or at least far more infrequently) failing cogs and chains !!

    I believe this is a combination of updating the following three variables:

    Time of Stop on the PAS tab: I set this to 5 to resolve the issue described above where the PAS does not cut off quickly enough before shifting, causing wear. It seems to shift very well now when I use PAS.

    Start Current (%) on the PAS tab: Adopting Karl's recommendation here may have helped as well.

    Start Current (%) on Throttle Handle tab: I believe this variable was originally set significantly higher than Karl's recommendation of 10. I believe the power jerk upon startup wore on my cogs and chain. Related tip: Start the throttle slowly. Don't jam it down suddenly.

    I would recommend adopting Karl's Special Sauce for all variables except Time of Stop, which I'd recommend setting to 5.
    Last edited by Squeamish; 02-25-2020, 06:17 PM. Reason: Added new info at bottom of post.

    I run sintered metallic brake pads. They last longer and are designed for higher speeds. Be careful adding them to hydraulic brakes. Some brakes can boil the fluid. This might happen with organic pads also.
    I would see what Downhill racers are running for brakes. The weight and speeds are similar.


      That's a pretty good overview, nice. Key points:

      Keep your chainline hardware in tip top shape, including adjustment. And, don't lug it.

      I need to turn my shift cable a click or 2 just for temperature changes, or it's a bit off. Good way to test this is to compare time for upshift vs downshift. If one is slower than the other, balance it. This allows much more sensitivity than waiting for obvious noises.
      Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.


        I have placed aluminum heat (go with copper if you have the money) sinks all over my BBSHD and controller (ludacris) and have never had a heat problem even during my learning experience while running in the smallest gear and lugging the motor. I beat the living hell out of my BBSHD due to my inexperience and never melted a nylon gear. Actually, when I did the steel replacement, my nylon looks brand new.

        Consider heat sinks.

        These or these or any other size and be sure to use the proper adhesive.

        When I make the leap to 72v and the new BBSHD controller Luna is making I'll likely do a liquid cooling system on the motor. No, it's not needed but, I'm a geek and I like to put shit on other shit. lol
        Last edited by GenChad; 02-07-2020, 05:52 AM.


        • JPLabs
          JPLabs commented
          Editing a comment
          Can you comment about any change in noise character and volume, with the steel gear? My nylon ones have become silent, and I like that, but would probably drop in steel if not too noticeable. But, I suspect it probably would be pretty loud....

          What do you think?

        • AZguy
          AZguy commented
          Editing a comment
          Good question - since they are helical maybe not too bad

          I can hear my BBSHD when I'm riding on grass and tire noise is very low but I suspect it's the spur cut secondary reduction making most of the sound

        Instead of water cooling I would look into heatpipes. If you study how they work they're actually pretty high tech. Room temperature, solid state, phase change would be a good start on describing them.
        But they transfer heat through pipes just like water cooling so in the end it doesn't matter much which way you go.


          Cool, will do. I don't have a heat problem as it is, I just like bolting useless shit together. haha


            If you did this to a TSDZ2 it would be useful R&D. at 750W those do have a serious heat problem. But they have other issues also. So I can'r recommend them unless you're looking for adventure.


              To those asking about the steel gear sound. I replaced my nylon and repacked all my grease and the steel gear is quieter than my nylon was.
              This may not be the case for most users but I suspect a good grease and careful attention to CLEANING EVERYTHING OUT of the motor will help you as well.

              I actually don't expect anyone will have a quieter gear. It may be I had a fitment problem before changing the gear which was corrected during my upgrade but, I really doubt it. I ran it at 60 amps for about 5 minutes and the motor was very warm. The controller was fairly cool to the touch. I have to reinstall my heat sinks though after my upgrade. After that, I'll test the 60 amps again and see what's up.

              All in all, I highly recommend this gear swap. Unfortunately, Luna is out of the steel gears already. They don't seem to last long.


              • JPLabs
                JPLabs commented
                Editing a comment
                Wow, ok, thanks for that commentary.

              Originally posted by Retrorockit View Post
              I run sintered metallic brake pads. They last longer and are designed for higher speeds. Be careful adding them to hydraulic brakes. Some brakes can boil the fluid. This might happen with organic pads also.
              I would see what Downhill racers are running for brakes. The weight and speeds are similar.
              Sintered with what? Doesn't sintered mean the metal has been impregnated with oil or lubricant? I thought that's was a sintered brass bearing was.


                Sintering just means fusing things together - normally at lower temperatures

                With brakes it specifically refers to fusing the metal (e.g. copper) with other stuff

                With bicycles, generally speaking:

                Metal brakes are best for pad longevity and short term braking power but tend to be noisy and are usually bonded to steel backing plates so can more easily overheat on long downhill type use

                Organic pads on aluminum backing plates are usually best for downhill use since they will dissipate the heat better but they don't tend to last as long as metal - they are quiet but tend to the expensive side of the equation

                Organic on steel tend to be inexpensive and quiet so often what bike shops will use to keep customers from complaining about noise but they don't tend to last long and not good for downhill

                Outside of the biking market it gets a lot more complicated with gobs of formulas... I'm more familiar with moto brakes but here's an example of many different types:


                • Retrorockit
                  Retrorockit commented
                  Editing a comment
                  The heat transfer problem becomes an issue when running sintered pads on hydraulic brakes. I run sintered pads on Avid BB7 cable brakes to avoid that, and the sintered lining avoids the issue of frequent pad adjustments for wear. The hydraulic brakes self adjust.
                  My setup doesn't have a problem with boiling fliud- there isn't any.
                  The sintered linings when "overheated" don't release gasses, and oils like organics can. Noticeably better braking from 35mph than the Avid organic pads.
                  Larger rotors increase the leverage of the brake, and have more surface for cooling the rotor, but the speed of the rotor through the linings goes up so they run hotter there.
                  More braking = more heat. 2x speed-4x heat.
                  Bicycle brakes aren't designed for the speed of an E bike, and an E bike can repeatedly stop from 30mph, while a bicyle will have a long cooling period between high speed stops. Downhill racing comes the closet to matching that situation. I've seen aluminum cooling fins on the brake pads for hydraulic brakes. IDK what setup DH racers are running for hydraulic brakes. I haven't found a need for them myself. Also no hills around here so I can't just go look.
                  Last edited by Retrorockit; 02-10-2020, 08:28 PM.

                • AZguy
                  AZguy commented
                  Editing a comment
                  It's only occasionally I'm doing much downhill and I generally take it slow when I do

                  The pads that came with my bike were organic and lasted maybe 1500-2000mi and were totally shot... I replaced with metallic and at 6000mi total on bike they are still going... although it won't be too long before I'll be looking at replacements... but they are lasting something like 2-3x as long... they were noisy at first but once bedded not much noise


                I'm still running whatever pads came on the bike. I'll be swapping for metalic when these pads fail. I have replacement brakes for the whole system because the bike came with M680's or something and they are reportedly poor brakes. I haven't really had an issue with them but when I placed my orders for parts during the build I ordered some better brakes (dual piston for front).

                I love sticking heat syncs on stuff though so if I end up with a heat issue, I'll use some syncs.


                  When you buy brakes look into what type fluid they're using. Mineral oil is common but boils at a low temp.. OK for most bicycle use. DOT rated automotive/ motorcycle fluid is designed for much higher temperatures. This will probably avoid any issues with overheating the calipers. I ride fast street and with stickky street tires and pavement under me the added sensitivity of hydraulics is wasted. Also BB7s are respectable in this area compared to other cable brakes. But I noticed better braking from high speeds immediately when I switched to sintered Copper pads. At high speeds the brakes would start off good and then rapidly start to lose power with the organics as the pads overheated. This is during one high speed stop. Not long downhill or anything extreme. Don't try to switch fluids on a system. The rubber seals are quite different for the 2 fluids and you'll just ruin everything. There are good cable brakes, and there are good Hydros out there also. Also more bad than good for E bike purposes. Anyway I'm a beliver in metallic pads for Ebikes, and not sold on hydraulics for my own use. Do some research before combining the two.
                  Actually here's a page on this for bicycles. Since I'm a retired truck mechanic what I said might be old info. in some cases.
                  Last edited by Retrorockit; 02-11-2020, 07:52 AM.


                  • Retrorockit
                    Retrorockit commented
                    Editing a comment
                    That page stops short of discussing E Bikes or DH racing applications.So it's just a start.
                    I might add that from a maintenance perspective a brake bleeder is not in the proper location to remove pooled water from a mineral oil system. An alcohol based sytem (DOT fluid) will remove the water because the water is absorbed by the brake fluid itself..
                    The sintered pads I use on my BB7s will also fit Avid Juicy brakes. They are specifically NOT recommended for that application, and Avid uses DOT fluid!
                    Brakes are one place you don't want to get it wrong. Especially on a Ludicrous powered bike.
                    For me big rotor BB7s with full metal Copper pads don't leave much on the table.Too many things to go wrong with hydraulics.
                    Just like the trucks I worked on still use air brakes that are very old tech.Fault tolerant, and fail safe. They can tolerate a certain amount of leakage, and if there's not enough air pressure they won't release/ or will self apply and stop the truck.Even moving to disc brakes, the tractor trailesr are sticking with air.
                    Last edited by Retrorockit; 02-11-2020, 08:37 AM.

                  What’s the maximum voltage we can run on the bbshd with a ludicrous controller? Currently running a 52 volt system and thinking of going to 72 volt...


                    60V is the accepted maximum

                    The ludicrous controllers are no different than the stock ones in this regard