Chain popping on Bulls Six50 E2 Street

[Quito]

Hi all -

My wife's 2018 Bulls Six50 E2 Street has stock gearing and components, and often the chain pops off the front sprocket. LA FlyRides here in LA replaced the chain (KMC E10 chain, 10 speed, 136 link) but the problem persists. When I clean it the problem seems to stop for a few weeks, but eventually resurfaces. LA Flyrides is aware of the issue but has not suggested replacing any components, so I assume they don't know what's causing it either.

Does anyone know if this is common on this ebike? I'm willing to replace any components necessary if I could find what causes it.

Thanks in advance!

Quito

 

[LimboJim]

I'd try a new chainring next, but if you go with OEM, it could be expensive and take quite awhile to obtain - this may be why your dealer didn't do so. The motor that came with that bike - Bosch's CX Gen2 - used a 15T sprocket that turns 2.5 times with each pedal stroke, but the OEM version can be hard to find, even for authorized dealers.

There are less expensive aftermarket options, but most of the ones I've seen don't have the chain/bash guard built-in like the original does. Sometimes, however, you can find that stuff on eBay or Ridewill. Be ready to lay out for shipping and be patient though, as it will probably come from Europe.

 

[LimboJim]

Just occurred to me that a friend of mine bought my 2015 Haibike with the same 15t sprocket as yours (including chain guard), but he seldom cleaned and never changed his chain for over 1k miles. This wore down the teeth of his sprocket, and it didn't work well with a new chain when he needed one.

He had to replace the sprocket and his cassette - he went with an inexpensive Samox 16t sprocket. It works and has the built-in chain guard, but I wouldn't be surprised if it doesn't last long. It's probably not made with very high quality steel...

 

[fooferdoggie]

doing this helped a lot. getting rid of the chain guard and adding this chainring guard.

 

[LimboJim]

doing this helped a lot. getting rid of the chain guard and adding this chainring guard.
View attachment 100809

Is that a Miranda chain guard? Whatever it is, any chance you remember where you got it and for how much?

 

[fooferdoggie]

Is that a Miranda chain guard? Whatever it is, any chance you remember where you got it and for how much?

sure just bought another for our tandem. https://www.amazon.com/gp/product/B01N5A610D/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 you also need this guy to remove the locking. there are cheaper ones maybe 15.00

https://www.amazon.com/Park-Tool-LRT-1-Lockring-Chainrings/dp/B083WLN45B/ref=sr_1_3?dchild=1&keywords=bosch+chainring+tool&qid=1632344996&sr=8-3

 

[Quito]

Thanks LimboJim and Fooferdoggie (great looking bike - looks different than ours and customized)!

With this upcoming service, we'll look into replacing the chain, front chainring (probably the original with 5k miles on it, after 2 chains and 1 cassette during its lifetime), and add the Miranda Chainring Guard.

@LimboJim - do you think this chainring would work? Our bike has the Performance Lines Speed motor:

Amazon.com : BOSCH Unisex_Adult Kettenblatt, 15 Zähne Chain Ring, Black, Standard Size : Sports & Outdoors

Amazon.com : BOSCH Unisex_Adult Kettenblatt, 15 Zähne Chain Ring, Black, Standard Size : Sports & Outdoors

www.amazon.com

Sorry, but what's the difference between a chainguard and chainring guard?

 

[fooferdoggie]

I have almost 12,000 miles on my cassette and chainring. well maybe a couple thousand less on the chain ring. its starting to get noisy though, but we are talking 5 chains so far. the chain guard is the plastic thing that covers the chain mostly.the chainring guard is what I posted picture of and a link I like the sram chainrings they are really durable. https://www.ebay.com/itm/373426632781

 

[Quito]

@fooferdoggie - Ok then, I don't believe ours came with a plastic chainguard, just the black chainring guard. I just wanted to be sure I identified all the parts we should replace. See this photo below from when it was new.

Other than number of teeth and if it's for ebikes, do you know if there's anything else special we should look for compatible chainrings on the 2018 Performance Line Speed motor?

This SRAM looks also good, with 16T vs original 15T: https://smile.amazon.com/SRAM-X-Syn...&pd_rd_wg=AgbQ1&pd_rd_i=B06XZLX36M&th=1&psc=1

 

[fooferdoggie]

our tandem had that one too but in the crash it got trashed. so you dont need a new one unless it brakes. ours was attached to the crank arm and then the crank arms had to be replaced it was gone. thats the right chainring. you need this tool or one like it https://www.amazon.com/Park-Tool-LR...ds=bosch+chainring+tool&qid=1632344996&sr=8-3
I use a 18 I can climb hills great and 30mph is where I spin out. but 16 would really give you some climb ability. anymore I can get up any hill on tour and don't need turbo now.

 

[Quito]

Oh if I understand correctly, I should only replace the chainring guard shown in the photo unless it broke, (and it hasn't). Maybe then I should only replace the front chainring. I'm looking for 15t or 16t only (18t is too large for her with the hills she needs to climb).

Do you think this chainring will fit onto the motor and existing chainring guard? https://smile.amazon.com/SRAM-X-Syn...&pd_rd_wg=AgbQ1&pd_rd_i=B06XZLX36M&th=1&psc=1

Sorry for so many follow up questions!

 

[fooferdoggie]

Oh if I understand correctly, I should only replace the chainring guard shown in the photo unless it broke, (and it hasn't). Maybe then I should only replace the front chainring. I'm looking for 15t or 16t only (18t is too large for her with the hills she needs to climb).

Do you think this chainring will fit onto the motor and existing chainring guard? https://smile.amazon.com/SRAM-X-Syn...&pd_rd_wg=AgbQ1&pd_rd_i=B06XZLX36M&th=1&psc=1

Sorry for so many follow up questions!

yes I would not chan the chainring guard unless you like the looks of it. yes if she has trouble then a smaller chainring will really help. it will get noise though I found. but thats the right one you have the second Gen motor it looks like.

 

[Quito]

Thanks again @fooferdoggie. I ordered the 16T SRAM chainring and will see how it goes (noise but no more popping ). I appreciate your time and help. Cheers! Quito

 

[fooferdoggie]

I went from 22 to 18 and the chain noise increased. but man trying to climb with the 22 was not fun.

 

[Quito]

22 does sound hard to climb with - I have an 18 with 41 on largest rear and I need to use Sport or Turbo.

We decided to also order an 18t, and decide which is better for her (with 36 largest rear). Thanks again!

 

[LimboJim]

Oh if I understand correctly, I should only replace the chainring guard shown in the photo unless it broke, (and it hasn't). Maybe then I should only replace the front chainring. I'm looking for 15t or 16t only (18t is too large for her with the hills she needs to climb).

Do you think this chainring will fit onto the motor and existing chainring guard? https://smile.amazon.com/SRAM-X-Syn...&pd_rd_wg=AgbQ1&pd_rd_i=B06XZLX36M&th=1&psc=1

Sorry for so many follow up questions!

The OEM front sprocket on many Bosch Gen2-equipped bikes is one piece with the guard, so I you may need to add a guard to the SRAM chainring.

Fooferdoggie found Miranda's separate guard available on Amazon - I couldn't find one back in June!

 

[fooferdoggie]

The OEM front sprocket on many Bosch Gen2-equipped bikes is one piece with the guard, so I you may need to add a guard to the SRAM chainring.

Fooferdoggie found Miranda's separate guard available on Amazon - I couldn't find one back in June!

I wonder if our tandem was like that? they lost the gaurd when they replaced the crank arms and they included a sprocket in the parts return.

 

[Quito]

Hmm - thanks for the heads up, @LimboJim. Well, I initially ordered the Miranda guard from Amazon with the 16T sprocket. Then later cancelled the Miranda guard and ordered another 18T sprocket. I hope Amazon doesn't get confused, because now I just re-ordered the Miranda guard again!

 

[fooferdoggie]

You will need a crank arm remover too. https://www.amazon.com/Skylety-Remo...Puller&qid=1632415334&s=sporting-goods&sr=1-5

 

[Quito]

Thanks. Good to know but I'll have the shop do it when they replace the chain, as part of the tune up service they partially completed.