Scott E-Genius and Chain Suck

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  • Scott E-Genius and Chain Suck
  • I have had regular chain suck issues on my E-Genius. The front cog is very small and as soon as the chain hooks even a little bit it wraps itself round and the pedals stop – very suddenly.

    Remember the cog turns 2.5 times for every turn of the pedal so you get a fraction of a pedal turn before it all goes bad.
    [url=https://flic.kr/p/Wo7w1i]20170811_154910[/url] by WCA!, on Flickr

    Since sticking a new chain and rear cassette the problem has escalated so I can hardly take a pedal stroke without it all locking up. I ordered a replacement but still waiting for it to arrive a week later!

    I decided to take the old cog off and see if I could diagnose the problem. It didn’t seem particularly worn or ‘hooky’ but I was struck by how long the teeth were.
    [url=https://flic.kr/p/X1vW3S]20170811_154933[/url] by WCA!, on Flickr

    Compared to a normal front cog.
    [url=https://flic.kr/p/WkNCm3]20170811_154954[/url] by WCA!, on Flickr

    The teeth actually stick out through the chain
    [url=https://flic.kr/p/XxuiDm]20170811_155018[/url] by WCA!, on Flickr

    This definitely doesn’t happen on my other bike
    [url=https://flic.kr/p/XmHcMh]20170811_155139[/url] by WCA!, on Flickr

    I decided the safest thing to do was to grind off the end of the teeth
    Before:
    [url=https://flic.kr/p/X1w1PW]20170811_155309[/url] by WCA!, on Flickr

    After:
    [url=https://flic.kr/p/Xpsk6X]20170811_155552[/url] by WCA!, on Flickr

    And then a little fettling with the hand file and the chain suck disappeared!
    [url=https://flic.kr/p/XmJgoU]20170811_155931[/url] by WCA!, on Flickr

    Premier Icon somafunk
    Subscriber

    The only time i have experienced chainsuck on my Scott E-Genius 710 was when i attempted to replace my chain at 600miles use due to it showing more than .75 of wear according to the park chain gauge, i replaced it with a Kmc 11speed chain and it immediatly suffered chain suck and dragged the chain round the front cog, i thought it may be the KMC chain so i tried a barely used XT 11spd chain but it had the same issue so it made sense to refit the original chain and continue to ride the current drivetrain into the ground – 3500 miles later and i’m still on the same drivetrain, it still shifts crisply so i imagine i’ll get a bit more use out of it before i need to change anything. I have a new front cog/chain/cassette waiting to fit when it finally goes pop, the front cog is specifically made for the scott e-genius model (and rather expensive at £50+) with longer teeth to hold onto the chain over rough terrain and with the torque available i guess the longer teeth are also used to ensure a secure drive when under load from the motor so i’d be wary about filing it down but it seems to have worked for you.

    Somafunk – I had to change the chain after catastrophic chain failure led to a slow walk home with a busted knee cap. I have also been thrown over the bars (taking out the computer) after chain suck stopped me pedalling. I also spent an evening in Re-suss ward and then Major Trauma when I was suddenly thrown from the bike.

    The hospitalisation occurred on a bike that was delivered with the rear shock mounted upside down, the cables for brakes set up incorrectly and various other issues.

    This was replaced under warranty by the shop I bought it from after the last big crash.

    The new bike was a massive improvement and has been brilliant, right up to the point the chain snapped. I don’t do massive mileages but accept I might not be the lightest rider.

    It appears you had the same problem when you tried to renew your chain but had the option of refitting the old one.

    I didn’t have that option so did what I could to make the bike usable.

    I love the bike but I am irritated with how much time it has spent off the road.

    This thread was designed to help anyone who had my drive train issues. I am glad you haven’t suffered the same, it is SO ANNOYING.

    Right now though I am happy having been blasting Southampton Bike Park like a little kid!!!

    z1ppy
    Member

    M8 has struggled with chainsuck on his two e-bikes (bosch motors). Can’t say he found a great solution with his latest one, changed chains, front sprocket, rear mech (had issues & the bike shop owner was good enough to exchange it with his own) & due to the casing not fitting particularly well, a newer case shell. He again blames the small front sprocket, though the cube case with the newer anti-chain suck moulding actually makes it worse, I’ll point him towards this thread

    Rorschach
    Member

    “a slow walk home with a busted knee cap. I have also been thrown over the bars (taking out the computer) after chain suck stopped me pedalling. I also spent an evening in Re-suss ward and then Major Trauma when I was suddenly thrown from the bike.”
    You are Frank Spencer and I claim my £5.

    Mrs M’s cube ebike with Bosch motor suffered this after I replaced the chain. New sprocket fitted to front at this point. From what I’ve read on ebike forums it seems chain and sprocket should be replaced together.

    Premier Icon rsvktm
    Subscriber

    Mate had this issue with a Bosch motor and after new chain, new sprocket and trying diff lubes put a clutch mech on. Sorted, not had an issue since and done fair few miles in some very muddy conditions.

    Premier Icon martymac
    Subscriber

    I also have a cube ebike, i snapped a chain a few months ago (the day after i let someone ride it who had zero mechanical sympathy, changing gear under full power)
    Fitted a new chain.
    No problems at all.
    Bike is fitted with a clutch mech, maybe thats the solution?

    tjagain
    Member

    That front sprocket is totally worn out – thats your issue.

    Premier Icon imnotverygood
    Subscriber

    The chainring on your other bike is also worn out.

    Clutch mech helps but doesn’t totally solve the problem.

    Cog may be worn out now, new one on order, but chain suck has happened since the bike was new.

    Other bike cog may be worn but still runs perfectly so will be staying in place for the moment.

    Premier Icon martymac
    Subscriber

    How many miles has the front sprocket done?
    My wife has another cube ebike, which has a normal mech fitted, it hasnt had any chainsuck either.
    Although, both bikes have only done around 600 miles.

    Premier Icon zilog6128
    Subscriber

    Interesting thread. Could be a design weakness with the Bosch system, a few bike co.s are modifying the stock unit. Cannondale have added their own chain retention device & custom 15t chainring, offset 6mm compared to standard for better chainline.

    The 2017 e genius no longer uses the bosch unit. I don’t think it works well in much conditions. It might be okay when perfectly set up but mud gets trapped between the chain and two plates either side very easily and that causes chain stuck as well as any double in the chain ring.
    The grinding of my chain ring teeth has worked though. No chain sick at all on the last ride.

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