Electric conversion to a Quest 451

Discussion in 'Innovators Workshop' started by crazy_ebot, Feb 7, 2018.

  1. crazy_ebot

    crazy_ebot Active Member

    Hi all, I'm considering an electric conversion for a Quest 451 (the one with the e-ring).

    I think my options are hub motor in the rear wheel, or mid-drive out on the crankset. In either case I want something small and (relatively) light: I'm looking for low power and sustained distance. I'm not looking to break the sound barrier, or have so much torque that I smoke the wheels when crossing an intersection.

    The 451 feels like a pretty light bike. I'm leaning towards attaching a small (4.3kg, or 3.6kg, depending on which website you visit - odd) mid-drive to the crankset (Edit: After some web surfing, it looks to be a rebranded Tongshen DSTZ2), but I'm not sure what effect that might have on the steering/handling.

    I did a quick Google search - didn't turn up much besides a Instagram posting from a guy who DIY'd a mid-drive onto a Softrider. It looked kinda awesome, but the couple of comments he received were negative, citing potential handling issues. link can be found here: https://imgur.com/gallery/IH3WF

    Rather than take some random-negative-instagram post-commenter... as gospel, I thought I'd ask if anyone here has a more informed/considered opinion. In the meantime, I'll browse these forums and see what I can find.

    Last edited: Feb 7, 2018
  2. bret

    bret Active Member

    As you're near Perth, you might talk to Solarbike in Fremantle. Henry only works on weekends, but he has a conversion, and he helped me put my NuVinci hub in.

    There are others who work there who might have more knowledge - he's just the one I know of, but at least he's heard of Cruzbikes.
  3. bladderhead

    bladderhead Zen MBB Master

    Rear hub is good, because the other idea adds weight to the front, which could make the steering go weird. And an electric rear wheel is easy to detach. And less danger of spin.
    mzweili likes this.
  4. bret

    bret Active Member

    I have not done this yet myself, but I know I can lose traction on the front going up hill - with a rear drive motor, I will have what I need in all attitudes, particularly in traffic. It might also help with times I stop facing up hill, but haven't shifted down enough, such as an emergency stop.

    Plus I can take it off easily for touring.
  5. crazy_ebot

    crazy_ebot Active Member

    I know Matt and Henry! I first met Matt when he had a small shop in Perth. Bought an Electric bike for my wife, then found them again in Freo a year later. Matt and Henry put a motor in my Elliptigo. 2-3 years ago.

    I emailed Matt today: he thinks either option is possible. He couldn’t advise which would be best though (which is fair).

    I was thinking: some Cruzbike riders mount a clear windshield on the front of their bikes. Wouldn’t that weight also affect the steering, and if they’re okay with it... not doubting the weight doesn’t have an impact, but I’m wondering by how much.

    Hub motor in the rear would be the most straightforward, but having had a hub motor in a 20" wheel for a while (see earlier comment re: Elliptigo)... I just love the way the 451 rolls. Sigh. :}
    Gary123 likes this.
  6. bret

    bret Active Member

    I make my choice (haven't acted on it yet) because I can slip the front wheel going uphill, on less than perfect surfaces - a motor on the front will only make that worse.
    And I want the extra traction on the rear wheel - I only need the boost going up hills.
    And it's easy to swap out the motor wheel in the back leaving me a 'clean' bike for long rides (except the wiring harness).

    If you put in the hub motor, we'll all find out - let us know. Maybe you can sell it to me to put in my Tern P24H.
  7. crazy_ebot

    crazy_ebot Active Member

    Had to google what a tern P24H was. Cool.

    Years ago when I first owned a Q559, I had a few slips on the front wheel going up the bridge over Claisebrook train station. I put that down to me being in too high a gear.

    Also I had panniers on the bike... But, wouldn't it be better in that situation to have more weight at the front and not less? Apologies if there's a perfectly sensible physics argument refuting that assertion.
  8. bret

    bret Active Member

    I agree it may be better to have more weight on the drive wheel. You'll have to see whether that drive wheel would be better in the front than in the back going up hill. Putting a rear motor on puts more weight on the drive wheel going up hill - but the drive wheel is the one in the rear in that case.
  9. crazy_ebot

    crazy_ebot Active Member

    Here's a crazy thought: I try both.

    I already have 20" front wheel motor on my Elliptigo. I can remove the wheel... Put that directly into the 451's rear fork and test it out.

    And since I've been thinking about converting our spare bike (we use it to carry our youngest around), I could get the mid-drive, try it on the cruzbike and if it doesn't work out, put it on said spare.

    Bret, if you're in Perth, you're welcome to have a play on both configurations.
  10. benphyr

    benphyr Active Member

    I thought I read somewhere that some types of hub motors allow free wheeling when not engaged or have very little (like a free hub) friction when disengaged.

    Here's my pros/cons for front mid-motor:
    -motor weight is non-rotational so acceleration and deceleration will be easier for comparable size motor.
    -possibly small increase in traction on front wheel,
    -Weight up front: would not be impossible, starting, very slow speed, and walking the bike would be awkward because of the additional weight at the front but not remotely as bad as the person commented against the imgur post.
    -possibly forward shift in centre of gravity may be undesirable though I doubt it would be a deal breaker (I have a much higher centre of gravity on my conversion kit than you are likely to ever be able to get with a Quest and very good brakes and I would have to try really, really hard to approach lifting the rear wheel.
    -extra power to drive wheel likely makes spinning in loose and/or uphill situations worse (at least without careful management - you could probably get started with careful management of the electric before putting the thighs to work with their less even power delivery)

    Rear hub motor:
    -2nd wheel pushing - All wheel drive - spreads acceleration over two wheels when used so less likely to spin either wheel. better handling, traction, and acceleration whenever you might need it.
    -weight in hub is rotational so may make acceleration and deceleration a little less responsive when not using the motor (compared with mid-mount and assuming equal weight.)
  11. crazy_ebot

    crazy_ebot Active Member

    Thanks ben, those points make sense to me (as do brets).

    The mid-drive motor I'm considering says it has torque-sensing as part of it's pedal assistance. I think its a rebranded Tongshen DSTZ2. Having had a electric bike for a few years now, that only has a thumb throttle, I can testify that thumb throttle's over long distances tend to give you a form of thumb/RSI (I tend not to lean on the throttle which means I spend more effort holding the throttle in place).

    Maybe I'm making a false association between non throttle power management and motor type. I do know that cadence based pedal assistance tends to feel jerky, which is undesirable.

    On the other hand 'all wheel drive' sounds awesome. Though... having differing propulsion systems on each wheel might make it less awesome(?) not sure.

    ... But I'm going to test it and find out. : )

    ... Just a soon as I finish paving down the side of the house. Sigh.
  12. crazy_ebot

    crazy_ebot Active Member

    Rear hub motor test flight complete (20km ride).

    Hopefully the photos show up... I moved the kit across onto the Q451 last night, with just enough care to keep everything on, but not enough care that it will be hard to revert things back tonight.

    A few observations:
    • The existing torque arm wasn't compatible so I rode without it. The Cruzbike is an Aluminium Alloy frame... I don't think that's strong enough to run without one(?)
    • The Engine/Controller/Battery combo feels way overpowered. The throttle only needs the smallest push to get you going/flying. It’s awesome (and unsettling).
    • I’d like to try a decent pedal assist option for the bike as the throttle is problematic: when I'm pedaling a cruzbike, I often pull on the handlebar as well as push. Years ago with my Q559, there were times when I'd unintentionally pull/push myself into a dive to the right (no crashes thankfully). Using the throttle loosens your grip on the handlebar, which doesn’t cause the dive, but would be an issue if it did happen.
    • The bike is rock solid with the added rear weight. The push, combined with the seating design of the bike, is like accelerating in a sports car, or a small plane. It feels amazing.
    • I didn’t have any issues with the rear hub motor and wheel roll. It felt just fine, which is interesting. The added weight (between the battery and the motor) is substantial – doesn’t affect the handling (if anything, it may improve it), but it does affect the stationary mobility(?) of the bike, e.g. picking it up and moving it around (like say, on a train).

    Looking forward to trying a mid-drive next.

    IMG_6260.JPG IMG_6261.JPG IMG_6262.JPG IMG_6263.JPG IMG_6264.JPG

    P.S. I had my Henty Wingman hanging off the right side of the bike on this morning's ride. The bag has a small strap + clip at it's base that you can use to hold it to the right fork strut, preventing it from accidentally connecting with the rear wheel.
    Last edited: Feb 13, 2018
    tiltmaniac and super slim like this.
  13. bret

    bret Active Member

    My own understanding is that the torque arm is to prevent the axle spinning in the fork. The force from the motor either moves the wheel, or it moves the axle in the other direction - the torque arm prevents the axle being spun and damaging the fork.
    tiltmaniac likes this.
  14. crazy_ebot

    crazy_ebot Active Member

    Yeah, that's my understanding also. I left the kit on the cruzbike for a second ride to work today (mainly because the paving job I finished wasn't really finished, and by the time I was done last night I was knackered).

    On the ride I paid more attention to my acceleration. Worked on light pushes accelerating from a standing stop (e.g. the lights), and then just a touch of power at irregular intervals. The aim was to keep me rolling quickly, but my legs doing most of the work.

    The commute time was about the same, but it reduced the battery drain by 35-45%.

    Won't be riding it again (as is) after today though. Too worried about the torque... Given the unique design of the frame, don't feel like forking out (pun intended) for basically another bike.

    This tinkering makes me wonder what would happen if you converted an s40. I haven't ridden one, but they have to be the 'coolest-looking' bike ever made. : )
  15. bret

    bret Active Member

    If you converted an S40, you would no longer be made of money.
  16. crazy_ebot

    crazy_ebot Active Member

    Have I not established already, that I'm made of duct-tape and a cautious, naivey optimism? Apologies. : )

    The comment about the s40 was the idlest of thoughts.

    Scoured Aliexpress for the cheapest listing for a Tongsheng TSDZ2 mid-drive that meets the criteria of a) the vendor appears to know what they are listing and b) the vendor has a 99% trust/approval rating (I've never used Aliexpress before, but I figure they're good parameters).

    Update: I may have run into an issue with the mid-drive option. Looking at a manual, there's a fastening bolt config that I'm not convinced will fit with the moving bottom bracket (see pic).

    Last edited: Feb 14, 2018 at 2:30 AM
  17. super slim

    super slim Zen MBB Master

    If you use Aliexpress, there is NO comeback or warrantee of the components!

    Have a look at em3ev in Hong Hong, that has a very good reputation with Electric MTBs in USA!

    The 36 V 500 w Bafang BBS-001 Middrive motor, option will give a 78 rpm max efficiency speed, so you can pedal to add power, where the 48V BBS-02 has a 106 rpm max efficiency speed, just possible, and the 48V BBS-HD 150 RPM, not possible!

    With a $25 programming cable, the first 5 of 9 steps of the pedalec assistance can be changed to 30, 60, 90, 120, 150 watts, to choose the required assistance and a max speed of 78 rpm for 81.4% efficiency .
    The power required for a Silvio V1.0 45 deg seat, on flat ground, is 105 w for 26 kph, 170 w for 30 kph.


    The 500w BBS-01 comes with a 25 amp controller with high quality mosfets, where the 250 W comes with a 15 amp controller and standard mosfets, so the controller should be set for 18 Amps to allow for instant overruns, especially if starting at 0 rpm, where the efficiency drops to 20% and the current goes to the the max set, or the limit of the controller!

    The pedal motion sensor detects rotation only, so starting off in 1st gear when stopped, just like a car, and use low throttle(PAS level 2 or 3), with the crank speed increasing to and staying at 78 rpm and change up gears until you reach the speed required, and increase the PAS level if PAS 3 is not high enough!

    With a 36 T Lekkie chainring, and a 11-34 9 speed cassette, the 26" bike speeds at each gear at 78 rpm, would be 9.6 kph, 11, 13, 15, 17.5, 21, 23, 27, and 32 kph.

    A$45 us gear change sensor, cuts power for 0.5 secs, so the derailleur system is not subjected to up to 500 w of power, when changing gears.

    The Banfung BBS-01 will fit a standard BSA 68 mm Bottom bracket with no worries.

    0071.jpg BBS02Trike.jpg
  18. bret

    bret Active Member

    Have you discussed with Solarbike?
  19. crazy_ebot

    crazy_ebot Active Member

    Thanks for the exhaustive info Slim. I'd heard/read the Bafangs were cadence based, not torque based (which I figured was undesirable for a 20" wheel bike where visibility can be a thing?), and tended to be harder-wearing on the chain etc. I take it that's not your experience?

    I'm definitely taking on board your concerns regarding the dangers of buying from unknown online sources. I think I'm happier to pay 35% more and buy local, so that I can utilise Western Australia's awesome consumer rights. : )

    Hey bret - Matt/Solarbike's counter to my 'will this mid-drive work' was: 'we won't know until we try'... Which is hard to argue with, and always makes me grin (in a slightly unhinged fashion).

    Update: Found a thread on Endless Sphere discussing a bafang installation that I've previously only seen pictures of:-
    Last edited: Feb 14, 2018 at 9:58 PM
    super slim likes this.
  20. super slim

    super slim Zen MBB Master

    If you can find a good local Electric bike specialist, it is worth 35%!!!

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