Gearbox whine reduction

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jamesengland
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I've been thinking about the Vectrix gearbox whine. Whilst it is obviously caused by the straight-cut gears, I think it is amplified by resonance in the empty spaces at the back of the bike. Whilst the gearbox on my bike is not painfully loud or anything, it does whine and I've been trying to reduce it.

The swinging arm is hollow and particularly large on the left hand side. I removed the right side of the swingarm and had a good look around inside with a boroscope. There's a lot of space in there to resonate. I put mineral wool insulation inside the swinging arm crossmember, quite tightly packed, as far as the motor wires which run through the left side but not ON them (in case they get warm/hot in operation). Also, up the front part of the swinging arm which goes towards the bearing end of things.

The chromed plastic cover on the left of the motor has quite a gap under it and I filled it with a pad of mineral wool... not enough to require squashing and without any pressure being exerted on the encoder cover underneath... just enough to fill the space.

I ran the bike on blocks in my workshop and found there was a definite reduction of volume of the whine, with the added bonus of certain frequencies disappearing altogether. This made the overall noise far less obvious. I ran the bike for several minutes and then removed all the mineral wool and ran the bike again. It was a lot more pronounced without the wool.

The shape of the back end of the bike, with its bulbous panels and spaces everywhere, is like a giant soundbox. It even looks like two lutes stuck together with a seat on top (if you're a musician and have a fertile imagination). With the bike on blocks, I removed the rear wheel and ran the motor at various speeds throughout the range. I could actually feel the bulbous panels resonate at the lower frequencies (in the 20-30mph range especially) I used a stethoscope on the big panels and the gearbox whine is clearly audible through them. So, I'm going to remove the panels and stick foam blocks on the panels, making sure of course that the cooling airways etc are not blocked or disrupted. I've not been able to road test the bike, as it's throwing it down with rain again. However, with a noticeable sound reduction in the workshop, I think the road test will be encouraging. I'll do that next and post again with the results.

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Mik
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Re: Gearbox whine reduction

Great idea!

How do you keep the stuff away from the cables in the swing-arm?

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jamesengland
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Re: Gearbox whine reduction

Mik wrote:

Great idea!

How do you keep the stuff away from the cables in the swing-arm?

I poked a piece of bike inner tube in first, rolled up into a sort of bung. It opened up once in place and blocked the end of the swingarm. If the wires don't actually get hot, then I would certainly insulate the other side of the swinging arm, especially that big section.

I've been poking about tonight and had a look at the rear panels. There is even a gap between the panel and the inner mudguard thing... wide enough to get my fingers in. So, going on the resonance idea, that gap could allow sound in (like the slots in a violin) and the bulbous shape of the panel will amplify it. I've noticed that, on car doors, you get all sorts of bits of foam and sticky panels and things stuck inside them and this is to stop the panel from resonating at certain frequencies. Merely sticking a chunk of foam is enough to stop it. So, I'm going to stick some polystyrene blocks inside each of the rear panels.

One other thing, on the removable part of the swinging arm, there's a number of strengthening struts which make 'compartments' in the arm, facing the gearbox. I traced the shape of these compartments and cut some medium density foam pieces to shape, then firmly wedged them in. It's easy to use a hot knife blade or foam cutter to get them exactly flush with the surface of the swinging arm. The idea here is that anything in the 'whine-zone'that will absorb sound is a good idea. The foam has negligible weight, it will stop any possible resonance from that part of the swinging arm and it will absorb at least some sound.

I've been thinking about using the six gearbox cover retaining bolts to each hold a curved plastic clamp, same curvature as the cover. Each clamp could hold a block of damping material directly onto the gearbox cover, effectively forming a 'Polo' of foam clamped to the cover, able to rotate with the gearbox cover without hitting the brake caliper. Again, my theory is that anything sound-absorbent in the whine-zone is a good idea, so long as it's light and there's no danger of anything getting caught in the caliper (hence using plastic rather than metal clamps). So, that's the next step........ I figure that, if the whine is unavoidable, it can at least be reduced.......

I'll report back. Hopefully, it might even work!

MEroller
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Re: Gearbox whine reduction

jamesengland wrote:

If the wires don't actually get hot, then I would certainly insulate the other side of the swinging arm, especially that big section.

Careful with the phase wires to the motor, they DO get hot, I am sure, given the currents that flow in the VX1. I have had my own share of bad experiences with a too low-melting wire cover that my former dealer had put over my motor phase wires and actually shoved the end of it into the (hub-) motor's axle. The end result was overheated phase wires because they had also been thermally insulated by that cover, so much so that they melted the cover INSIDE the motor axle. The plastic flowed into the bearings, cooled and mechanically stalled the motor. So keep those phase wires as well aired as possible.

I have also thought about putting some PU-foam into the swing arm fairings on my Chinese ride, not so much to dampen a whining gearbox because there is none, but to dampen the creaking and groaning from the motor at low speeds, caused by the BLDC-type block-commutation of my Kelly controller. The fairings resonate "wonderfully" with those frequencies. A first step was to put some gaffer tape layers on the swing arms in those places were free ends/corners of the farings were close to the swing arms and caused them to vibrate onto each other, thus greatly amplifying the groans. At least THAT is now gone :-)

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My rides:
QvR vR one: a Swiss package of pure understatement - innocent and to some eyes (from some angles) exceedingly ugly looks, but with raw and hardly containable electron power up to real 95 to 100km/h! And a literally rock-hard suspension due to a carrying capacity of twice it's unladen weight... Now converted to more controllable and efficient brushless motor and vector-contoller.

E-Sprit Fury (basis is the Erider Thunder 5000) since May 03, 2011. Highly moded - but now in active retirement

jamesengland
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Re: Gearbox whine reduction

WEll, I went out for a 10 mile ride on the bike, at fairly high speeds (which flattened my batteries from fully charged.... eek!) There is no doubt that the sound dampening exercise worked. The gearbox whine is drastically reduced throughout the range. I'm very pleased with the results. I've yet to put blocks on the rear fairings and make the 'Polo' sound damper but I'll work something out and get back with results...

jamesengland
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Re: Gearbox whine reduction

Here's a uick follow-up. The measures I outlined above undoubtedly work really well. I've been out on the Vectrix and people who've been interested in it before have commented that it's much quieter. It's also obvious when riding but it's confirmed by a few 'ride-by' tests with friends listening acutely!

I would recommend doing the above. I've yet to make the foam 'Polo' but I think it will make even more difference.

I replaced the rear breather nut thing with a pipe, routed up under the rear light unit) and increased the amount of oil in the gearbox. This also helped. I don't think it's adversely affected performance... I put 120ml of oil in rather than 80...

jamesengland
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Re: Gearbox whine reduction

I fitted some expanded polystyrene blocks into the bulbous parts of the rear side casings. They are about 4" by 2" and I superglued them in place, directly to the cleaned inner surface of the casings. I've been for a burn this evening (cold....) and the gearbox whine is further reduced. There's a long street where I live, single carriageway and high buildings either side. The whine used to be very noticeable indeed going up this road. It's definitely much less now.

tt-tronix
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Re: Gearbox whine reduction

I have made different attempts to reduce the gearbox whine (different gearbox oil & additives) but without success :-(

This thread is an interesting approach for solving the problem. Keep on posting your results, I want to try it out soon...

Tido

jamesengland
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Re: Gearbox whine reduction

Will do. I've just got to make the foam 'polo' and that should be it......

kingcharles
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Re: Gearbox whine reduction

Did you by chance make some photo's of your mods?

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jamesengland
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Re: Gearbox whine reduction

Just done it tonight! I've made the 'Polo' and fitted it but I'll start from the beginning with the pix....

Here's the breather modification that allows a higher oil level in the gearbox (OK more drag but I personally don't think it's critical on a powerful motor). The theory here is that increased oil level will dampen the sound:

Here's the foam on the inside of the swinging arm:

Here's where I stuffed the mineral wool insulation:

Here's a roughly cut foam 'Polo'.......:

....bevelled on the inside (using a hot knife) in order to fit around the shape of the gearbox cover.

Here's the Polo, painted black and fitted onto the gearbox. I used the three holes which are for using a bolt to force the gearbox lid off when it's stuck. The clips are brass picture hanging brackets, bent over to hold the Polo in place. However, there is also clear silicone under the Polo and around the edges. The top tabs of the bracket has to be bent over to allow the wheel to go on...

Polo on the gearbox cover. Note how it is bevelled to clear the brake caliper assembly:

Wheel on:

All back together:

It's chucking down with rain here so I've not taken the bike out. I've spun the rear wheel to maximum RPM in the shed. I think there's a reduction in sound but it's difficult to be objective in a confined space, so.... I'll do a proper test tomorrow and report back....objectively. I think it's the totality of the mods that gets the noise down. It's probably best to do them all......

Looking at the pix makes me think maybe it's worth insulating the quadrants on the gearbox cover, behind the brake disc.......

Mik
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Re: Gearbox whine reduction

I wonder if some sort of "Space Invader" foam would work better for some of the parts, like the holes in the swing arm.

Rather than stopping sound waves after they were created, a foam that sticks firmly to the metal might dampen the vibrations and prevent some of the sound waves.

How about the kind of paint that is designed for application to the underside of cars, to dampen the road noise? Could that be used to paint the outside of the gear box and underneath the brake disk? It would add some viscous mass and might dampen the vibrations of the gear box cover.

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jamesengland
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Re: Gearbox whine reduction

Update re the foam....

I've tested the bike and found that the noise has been further reduced by the polo. Not as much as I thought it would, I must confess. However, I'd say it is worth doing, just to get a few more decibels/frequencies removed. The cost is minimal and it definitely does work to a degree.

I think the main thing with the slight mods in this thread are that it's the total of them that makes the difference. My bike still whines but it's noticeably less than before. I'd recommend spending the small amount of time to do the tips above.

jamesengland
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Re: Gearbox whine reduction

Mik wrote:

Rather than stopping sound waves after they were created, a foam that sticks firmly to the metal might dampen the vibrations and prevent some of the sound waves.

I don't think sound works like that. The only way to stop it being generated is for the gears to be different from what they are. They will always produce sound and it's a case of absorbing the sounds that are made, since preventing them is so difficult (ie helical gears, carbon fibre cogs or whatever). Of course, noise-cancellation works differently (eg in my Sony headphones) but it's not applicable here! Even then, it can't stop the sound being generated...it just cancels it by sending a similar sound wave back at the source of the sound and they negate each other.

No, I think the key is soaking up the sound, short of a drastically different gearbox.

One question though... on a bike of this expense new, and the generally excellent build quality, how did such a whiney, potentially noisy gearbox get through the design stage? I mean, they must have known, surely, that the gearbox was not exactly quiet? And yet they went ahead and produced it.....

jamesengland
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Re: Gearbox whine reduction

As part of my ongoing obsession re gearbox noise reduction, I've insulated the left side of the gearbox and also added small blocks of foam to the qudrants behind the brake disc. Here are some pix:

For now, I've left these blue but it would be easy enough to disguise them by painting them black.

I've also road-tested this further modification and there is no doubt at all that it reduces gearbox whine. In fact, the left side foam seemed more effective than when I did the right but, as I've said before, I think it's the totality of all this lot that makes the difference. I think the wheel itself may be amplifying the sound on the left.... the noise source is tucked smack in the middle of the wide rim. The gears are still whining inside, of course, but a lot of the sound is stopped from getting out or from resonating in empty spaces.

I've used fairly high-density foam. No doubt there will be better/worse foams out there from as noise-absorbency point of view. I must say though, that I'm pleased with the results and I would certainly recommend that people try it if they are driven mad by their gearbox whine.

ps. one other thing... I've found that once the silicone has set properly, the brass bracket things in the pix earlier can re removed completely. I used 335 low modulus clear silicone, by the way. This sets harder than the usual bathroom stuff.

HubCap
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Re: Gearbox whine reduction

I think the whine is very useful in heavy traffic... A Vectrix on regen breaking then acceleration sounds very similar to a siren in the distance. White helmet, Hi vis jacket, and the cars move aisde like the parting of the Red Sea!

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MEroller
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Re: Gearbox whine reduction

Now that is a very useful utilization of the gearbox whine LOL

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My rides:
QvR vR one: a Swiss package of pure understatement - innocent and to some eyes (from some angles) exceedingly ugly looks, but with raw and hardly containable electron power up to real 95 to 100km/h! And a literally rock-hard suspension due to a carrying capacity of twice it's unladen weight... Now converted to more controllable and efficient brushless motor and vector-contoller.

E-Sprit Fury (basis is the Erider Thunder 5000) since May 03, 2011. Highly moded - but now in active retirement

antiscab
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Re: Gearbox whine reduction

jamesengland][quote=Mik wrote:

One question though... on a bike of this expense new, and the generally excellent build quality, how did such a whiney, potentially noisy gearbox get through the design stage? I mean, they must have known, surely, that the gearbox was not exactly quiet? And yet they went ahead and produced it.....

gearboxes with straight cut gears are stronger and more efficient that helical

a helical gearbox would likely have been too heavy

straight cuts are also easier/cheaper to make

There's not much incentive for a manufacturer to make a bike quiet (as in not enough people seem to want to pay more for a quieter bike)

Matt

__________________

Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah
Vectrix 60Ah Lithium Tyres Fuel Registration Insurance cycle analyst 2 x TC Charger & MC
conversion
Spent so far: $5800 + $7000 + $2040 + $1200 + $425 + $800 + $140 + $3000
Cost to do it again: $1000 + $3800 + $2040 + $1200 + $425 + $800 + $140 + $1500 (lasts longer)
Cost for a Petrol bike:$6000 + + $1440 + $7560 + $1000 + $1600 + $4000 servicing
Total spent: $20405
Total to do again: $10905
Total to have used a petrol bike: $21600
Total distance travelled so far: 102'120km

Other vehicles:
2008 Mazda 2 conversion
2009 Blade Electron
1997 Prius - plugin hybrid mod

jamesengland
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Re: Gearbox whine reduction

antiscab][quote=jamesengland wrote:
Mik wrote:

One question though... on a bike of this expense new, and the generally excellent build quality, how did such a whiney, potentially noisy gearbox get through the design stage? I mean, they must have known, surely, that the gearbox was not exactly quiet? And yet they went ahead and produced it.....

gearboxes with straight cut gears are stronger and more efficient that helical

a helical gearbox would likely have been too heavy

straight cuts are also easier/cheaper to make

There's not much incentive for a manufacturer to make a bike quiet (as in not enough people seem to want to pay more for a quieter bike)

Matt

Well, in any event, my cheapo silencing system has cut down the noise quite a lot.....

ofx210p
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Re: Gearbox whine reduction

bizarrely mine is quieter now i've replaced the motor controller !

jamesengland
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Re: Gearbox whine reduction

ofx210p wrote:

bizarrely mine is quieter now i've replaced the motor controller !

That could be due to the controller sending a more accurate pwm wave to the motor. I believe it should reduce motor noise (although not gearbox, of course)

LeftieBiker
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Re: Gearbox whine reduction

I'm new to the Vectrix Experience, having just acquired a Leaf cell-converted VX-1. That loud whine, especially at low speeds, really struck me, though - if it weren't for that, I'd be complaining more about the bizarre seating position! Anyway, I plan to put synthetic gear lube in at the end of the riding season, and in the meantime may implement some of the sound-deadening foam techniques suggested here. First, I want to make absolutely sure that my gearbox isn't low on oil, but without taking it apart. Can someone point me to some videos, with sound, of VX-1s that are known to have full gearboxes? If I can reassure myself that a healthy VX-1 gearbox, full of good oil, sounds like a small jet taking off, I'll be better able to enjoy the bike.

EDIT: I've watched a few vids, now, and I'm getting kind of grateful that I don't have one of the noisier ones! It also appears to me that gear oil level probably has no effect on noise, except that when the oil gets too low it may eventually result in gear growling and cogging, but that's a guess based on what I've seen about gears that were apparently manufactured or assembled poorly. I'll try to live with the Jet Engine Whine, despite it setting off alarms in my old-school mechanic's brain about over-stressed gears and depleted oil. Since the VX-1 sounds kind of like the (post-production) Sixties Batmobile, I'll just pretend that my bike has a turbine.

zeuz
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Re: Gearbox whine reduction

Think on competition gearboxes... the tooth on the gears are strait, so that's why it whines... ;-)

Mine is loweder at 65Km/h and becomes silent at 75Km/h.
Others vary in this range.

The gearbox is supposedly maintenance free, but over the years people found a way to change its oil.
Now even its representatives show how to do it: http://service.vectrixparts.com/topics/221-changing-gearbox-oil-s-rw-gxoil/

antiscab
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Re: Gearbox whine reduction

Hi Guys,

I'm at 113'000km

I have never changed the Oil in my gearbox to no apparent detriment

The gears are straight cut and constant mesh in a sealed unit
unless it's leaking or the bearings are end of service life - leave it as is, anything else is a waste of time

if your gearbox is loud, opening it up won't fix it
only replacing it will

__________________

Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah
Vectrix 60Ah Lithium Tyres Fuel Registration Insurance cycle analyst 2 x TC Charger & MC
conversion
Spent so far: $5800 + $7000 + $2040 + $1200 + $425 + $800 + $140 + $3000
Cost to do it again: $1000 + $3800 + $2040 + $1200 + $425 + $800 + $140 + $1500 (lasts longer)
Cost for a Petrol bike:$6000 + + $1440 + $7560 + $1000 + $1600 + $4000 servicing
Total spent: $20405
Total to do again: $10905
Total to have used a petrol bike: $21600
Total distance travelled so far: 102'120km

Other vehicles:
2008 Mazda 2 conversion
2009 Blade Electron
1997 Prius - plugin hybrid mod

elevatorguy
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Re: Gearbox whine reduction

Both my VX have their own unique sound from the gearbox, I would like to be silent but I think the noise alerts drivers to my presence.
I consider it to be part of the personality of the Vectrix.
I had thought of changing the gear oil, but it doesn't bother me enough to crack into the gearbox.

LeftieBiker
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Re: Gearbox whine reduction

I understand that adding synthetic gear oil is unlikely to lower the whine, and will hold off on doing it until at least Fall - especially since I'll have to do the drill mod. I'll only do that to extend the life of the transmission; if I knew they put in high quality gear oil at the factory I wouldn't bother, but no one seems to know what they used, and with the factory in Poland it could be Russian Surplus Tank Oil. ;-)

Kocho
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Re: Gearbox whine reduction

I wouldn't touch it until at least another 10K miles unless it starts leaking. Antiscab knows a thing or two about Vectrix, and if he says it's OK to keep the gear oil in longer, I would trust him. My previous VX-1 I acquired when it was at about 16K miles, and it did not sound that much different from this one when I bought it new at only 136 miles. The sound hasn't changed for the past 3.5K miles, so I think it is working well.

The only somewhat successful stories of reducing the noise (but not eliminating it) are from folks swapping the three gears in different positions in an attempt to find the most quiet combination. I suppose, due to manufacturing tolerances some positions might be a little more quiet than others.

The noise does trigger an interesting reaction with pedestrians - it is not terribly loud, but it is unusual and they look at you with curiosity because of that, so they notice you.

At least the brakes on the Vectrix are quiet when in use (even though they might drag a little and be audible ar low speeds when not used). The ones on the Zero are very annoying at low speed braking - started to squeak and whine at low speeds quite noticeably. They were much more quiet when I test-rode it with you, now after about 60 miles or so they are much noisier. I hope as they set in they will become more quiet.

LeftieBiker
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Re: Gearbox whine reduction

I've seen complaints in the EMF forums about noisy Zero brakes, but the SR's never made any sound when I rode it. Of course, you have now equaled or exceeded the total number of miles I put on the bike! I assume that you charged it and didn't get the "BMS Isolation Danger (Will Robinson!!!)" warning? That's good, but I still think you are taking a big risk by riding it. Hopefully it just didn't like me.

It's unlikely that I'm going to do anything at all to the VX-1 before Fall, and still pretty unlikely I'll do it even then. I'm hoping that my brain will adjust to the whine, and I'll stop thinking uncontrollably, as I ride, that I'm chewing up the transmission. :-)

Kocho
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Re: Gearbox whine reduction

It shows error 20 and the red warning light is flashing so fast while charging, I can't count how many flashes to see what it means in the table with error codes... So I'm not riding it much - just had to have it inspected and registered, which is where the miles come from. I'm waiting for the Gaithersburg dealer to call me back with an appointment date for the service. And hopefully Zero will look at my email.

LeftieBiker
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Re: Gearbox whine reduction

The 0020 error was the first one to show - not counting the sidestand down and kill switch off codes. It was closely followed by 0028, IIRC. There seems to be supporting evidence for both a charging system short and a motor short, which isn't to say that the bike actually has both problems.

One thing I *may* do earlier than Fall is look into applying dampening plastic foam to the outside of the swingarms, or at least the right one, and the inside of the side body panels. I think if I could get a 20% reduction in the low speed whine I'd be satisfied.

LeftieBiker
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Re: Gearbox whine reduction

I went for another ride last night - gorgeous evening, but the roads were clogged with stinking Harleys - and noticed a new noise, or one I had somehow missed on the other two or three rides. When climbing grades and hills, the bike makes an oscillating whine, sort of like a chirping sound that repeats 3-4 times a second, along with the usual gearbox whine under load. Is this also typical for these bikes? I should be able to record it, as it's pretty loud, unfortunately.

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