Not buying Specialized ebikes again.

[mschwett]

Without knowing specifically what's in the SL motor, it's likely that the gear noise we hear is due to having straight-cut gear teeth instead of quieter (and more expensive!) helical-cut gears. If anybody here remembers manual transmissions on cars , they use helical gears except for the less used reverse gears, and you might recall that they made a whining noise when backing up. Also, doesn't the regular Vado use an internal toothed belt instead of gears to get the required reduction without the noise?

not having ever owned a car with an automatic i definitely know what you mean!! but is there some other advantage to straight cut gears other than cost? it’s hard to imagine that in a $$$,$$$ car with a manual transmission they’d still save a hundred bucks on a couple gears for reverse! more compact? lighter? stronger? reverse is usually the lowest gear ratio too right?

 

[Stefan Mikes]

Ha, now you tell me! Just ordered a Specialized through the local Specialized-only shop.

They've been very helpful so far, seem knowledgeable, and answered a zillion questions with a smile. Plus they're only 10 minutes from home.

The best Specialized owned LBS (the one I use, let it be "A") is located exactly 20 miles from my place. The other ("B") is only 16.7 miles but it requires a boring city ride, while the "A" needs a suburban ride including a well maintained forest. Both stores now try to act under the same umbrella to increase the sales of "B".

The major difference between A and B is I know everyone at A, am treated as a VIP there, and I reward the LBS by some shopping there. The "B" might be professionally good but they haven't built the vibe the A has got.

Anyway, having an LBS you can trust and is located nearby is the most valuable asset an e-biker can get. The guys at "A" have always fought for me with the Specialized distributor on warranty matters to the bitter end!

You read my "wobbly crankarm" report. I could have ordered the part from Germany. However, whenever I need a specialized part, I always give the "A" a phone call first...

 

[rochrunner]

not having ever owned a car with an automatic i definitely know what you mean!! but is there some other advantage to straight cut gears other than cost? it’s hard to imagine that in a $$$,$$$ car with a manual transmission they’d still save a hundred bucks on a couple gears for reverse! more compact? lighter? stronger? reverse is usually the lowest gear ratio too right?

You can't really slide helical gears together so the forward gears in your tranny are always meshed but not connected to the shaft that they rotate on when their gear is not engaged. When you move the shifter, what you are doing is sliding a mechanism that disengages one set of gears and engages another. This is called "syncromesh" and is why in a modern tranny you don't have to double-clutch or otherwise match revs to keep from grinding your gears when shifting. To do this with reverse gear would be a waste since reverse is always (or should be) engaged when the car is standing still and they can use straight cut gears that can be directly slid in and out of engagement while nothing is turning. Helical gears are stronger because a large percentage of the teeth faces is always engaged vs straight gears where just the tip of a tooth is engaged at a particular point. However, at the power level of an e-bike this is not really an issue.

 

[Kilowatt]

You can't really slide helical gears together so the forward gears in your tranny are always meshed but not connected to the shaft that they rotate on when their gear is not engaged. When you move the shifter, what you are doing is sliding a mechanism that disengages one set of gears and engages another. This is called "syncromesh" and is why in a modern tranny you don't have to double-clutch or otherwise match revs to keep from grinding your gears when shifting. To do this with reverse gear would be a waste since reverse is always (or should be) engaged when the car is standing still and they can use straight cut gears that can be directly slid in and out of engagement while nothing is turning. Helical gears are stronger because a large percentage of the teeth faces is always engaged vs straight gears where just the tip of a tooth is engaged at a particular point. However, at the power level of an e-bike this is not really an issue.

Straight cut gears are stronger, more efficient, and cheaper to make than helical. Helical are used only to reduce noise. Nobody cares how much noise a car transmission makes in reverse. Plus that slide together thing, I guess.

 

[Fender]

Here’s the soundtrack of the squeal that I was referring to. It was clearly noticeable anytime that I was pedaling without assistance which was often.

I suspect that simply replacing the motor rather than tearing it down and rebuilding it was Specialized’s way of avoiding any further delay to the customer.

I've had a very similar squeal on my Como, my LBS simply regreased the external seal of the crank shaft with a sticky silicon grease and it was gone
the fact that you can hear it with a backward movement is proof of that as when back pedaling almost nothing moves in a brose motor