mid drive ebike without shift sensor question (Yamaha Cross Core)

[Pfps823]

Hi,

New to the forum. Just got a Yamaha Cross Core. I like the bike a lot but broke the chain in the first 2 weeks! Did some research and see that maybe I was riding it too hard? It's a mid drive without shift sensors. Riding in high power most of the time. Also, for the first couple days forgot that I am supposed to pause pedaling while switching gears to stop the motor. Also, maybe changed mechanical gears while going uphill a few times....

So I'm wondering if there's some guide out there on technique for mid drives? Do's and don'ts... I've had a regular bike for 12+ years and never had any issues with technique or being hard on my chain/gearing... But I'm assuming something different with ebikes / middrives given the chain breaking so quickly.

I do enjoy riding this ebike on high power. Is that okay to do most of the time? Hoping so, as it's def more fun that way, which in the end is a big part of the reason I bought it!

Thanks. And sorry if this question has been asked a lot. Spent some time searching the forums but info I found mostly scattershot...

Peter

 

[TaraBara]

When I first started out I used to ride in high gear all of the time. I have a Giant with a Yamaha motor. I never had any trouble. I like you had forgotten how to ride a bike and broke a bunch of shifting rules and I had no trouble. Maybe you had a weak chain? It can happen....I hope your LBS replaced it free of charge? Your under warranty. The highest PAS is a lot of fun and in no way should harm your bike.

 

[Pfps823]

When I first started out I used to ride in high gear all of the time. I have a Giant with a Yamaha motor. I never had any trouble. I like you had forgotten how to ride a bike and broke a bunch of shifting rules and I had no trouble. Maybe you had a weak chain? It can happen....I hope you LBS replaced it free of charge? Your under warranty. The highest PAS is a lot of fun and in no way should harm your bike.

Yeah, I'm hoping just a defective chain. Yamaha doesn't warranty chain but since it's been 2 weeks maybe LBS will cut me some slack. Does seems a bit odd it went so quick...

 

[Pfps823]

I think you'll be fine without gear sensor. https://electricbikereview.com/foru...tronic-gear-change-sensing-shift-sensor.4399/

Cool. Good to know the sensor isn't a big deal once you get the feel. I pretty much figured it out myself intuitively after crunching the gears a couple times. At least I think...

Someone in that link mentioned cadence, and I've been also wondering if there's an ideal cadence you should be pedaling on these bikes? Sometimes, I like to ease off and let the bike do most of the work, but I think I read somewhere that the less you pedal, the harder the bike is working, which can mean more chain tension/wear?

 

[PaD]

I don’t think that during the 12+ years you’ve been riding and shifting gears on a regular bike you have applied as much power on the chain as you do now under full power from your Yamaha motor.
Never change gear when applying pressure.

 

[Mike TowpathTraveler]

Next time you are out riding your Yamaha, watch the front chain ring as you shift up or down while simultaneously easing up pressure on the pedals. The Yamaha drive will still turn the front chain ring a revolution or two, due to the Torque Sensor. This easing of the pedals while shifting at the same time will result in the derailleur gently move the chain to the next sprocket; the momentum of that front chain ring still turning giving a nice bump into the rear sprocket gear of your choosing.

This is how I pedal my Yamaha PW Drive powered Haibike Full FatSix. Same chain after 8400 miles of service. And I use the High power setting on the majority of those 8400 miles. And this is how you should shift your Yamaha, too.

This technique is the same employed by bike riders who have Internal Gear Hubs (IGH). Easing up on the pedal pressure applied to the crank arms on IGH rear hubs results in less torque and shock loading of the planetary gears within that hub, be it an IGH from Rohloff or Shimano.

I tend to think that you were a bit heavy footed on that chain. Chalk it up to one of those life with ebike lessons and go from there. And good luck with your Yamaha!

 

[Deleted member 4210]

I think you'll be fine without gear sensor. https://electricbikereview.com/foru...tronic-gear-change-sensing-shift-sensor.4399/

Yep. It knows when a shift is going to occur before you do. . Seriously it has 2 sensors that are measuring 1000 times per second, and using Algo's anticipates changes. 3 sensors total and the combined effect of all the sensing provides what the motor needs to know for when you shift. It's subtle enough where it's unlikely to be noticed. Usually a shift sensor is something you'd add for a aftermarket bafang mid drive, where torque can be between 120 nm and 160 nm depending on whether you have 750 watt bbs02 or 1000 watt bbhsd. Either one can rip your chain off or shred the rear cogs if you get crazy with them, and often is what happens with DIY'ers who like to buy those and press them to the max.


Eventually some oem (if they haven't already - just don't keep up with every development these days) is very likely going to incorporate machine learning, and we'll ll see some incredible performance like you've never imagined.

 

[Pfps823]

This easing of the pedals while shifting at the same time will result in the derailleur gently move the chain to the next sprocket; the momentum of that front chain ring still turning giving a nice bump into the rear sprocket gear of your choosing.

Great advice! Thanks. I’ll try this.

 

[Mike TowpathTraveler]

Great advice! Thanks. I’ll try this.

Hi Pfps! Looking over my post, I mentioned "easing up on the pedals" to observe the front chain ring still turning by the motor's electronics.

What I mean to say is to briefly stop pedaling and by that I mean a very, very short duration of a second or so, to allow the next shift to not be clunked or hammered into the next gear while high torque was applied to the cassette in the current way you are likely shifting your Yamaha.

Again, this shift technique is the same as that employed by the internal gear hub folks when they up or downshift their rear hubs when at speed. Good luck, work at it and after a while it will become second nature to you!

 

[Saratoga Dave]

It’s definitely a bit of an art, one I still have not completely mastered after about four months and fifteen hundred miles. I still clang them once in a while. I did have a Trek with shift sensing, and that was terrific. It took a little getting used to the Yamaha Motor on my Giant.

I’ve read about shifting at the top and bottom of the pedalstroke, which makes sense, but it’s hard to think that much about this stuff when you’re just out enjoying the ride. Hence the occasional reminder when the gears protest.