Scott Bosch gen 4 85nm update PROBLEM!

Carlos85

New Member
Mar 8, 2021
3
1
Leeds
Hi wonder if anybody can shed any light on this. So went for a ride to my local emtb shop where I bought my Scott egenius 910 just to look at some new magura mt7s he told me he would throw the new 2021 software in while I was there. So bear in mind had the bike around 11month 500 miles no problems whatsoever. Left bike shop within 500m bang chain came off front cog? At first thought it had snapped. so set off again put it in turbo straight off again did it about 7 times all in low gears and putting pressure on I've phoned bike shop there going to look? What's anybodys thoughts on this? Obviously it's the update but I carnt see what's causing it to do this maybe the extra power has bent the front cog maybe? My chain has never come off ever before it's weird. Thanks
 

Zimmerframe

MUPPET
Subscriber
Jun 12, 2019
13,771
20,455
Brittany, France
It's pretty unusual for the chain to come off the chainring unless you're on gnarly terrain, don't have a front chainguide/and or, the derailleur clutch is not engaged.

Quite often the front chainring will have a narrow/wide profile, so you have to make sure the chain is on the correct teeth.
 

Mikerb

E*POWAH Elite World Champion
May 16, 2019
6,105
4,636
Weymouth
It would have nothing to do with the software update. What other work was done on your bike by the LBS? You mentioned new brakes. Did they fit new brakes?
 

Carlos85

New Member
Mar 8, 2021
3
1
Leeds
Literally nothing I went in to book the mt7s in and have a browse he plugged in 5min update and I was off. Just wondering if the extra torque has bent the chain ring? Or bent a tooth. Im A big lad and maybe the extra 10nm has done some damage. All I know is done 500 miles hard terrain black runs and drop offs turbo on steep rocky inclines and it's never come off. IL see what they say when I pick it up this week if it happens again might go back to the old software if that's possible. My friend had a problem last year he had update was on a steep incline in the woods and it snapped chain and bent cassette one day after bit of a coincidence. He got it covered on Scott warrentee and been fine since. Fingers crossed they sort it. But it's definitely something since the update just don't make sense lol.
 

Zimmerframe

MUPPET
Subscriber
Jun 12, 2019
13,771
20,455
Brittany, France
The torque increase isn't that massive. You're only heading into Brose territory and not even Flyon territory.

You might think it's a combination of your massive power, but the reality is that the extra power isn't causing a problem it's just revealing a problem which is already there and has just been revealed a bit sooner. Your bike shop must be pretty cool if they updated your firmware for free.

You're not going to bend a chainring with your huge legs, you bend chain rings by smacking them on things.

The most likely option is that both you and your friend needed/need to change your chain for starters. They wear far far faster on an EMTB for a lot of people. Which in turn trashes the cassettes and the chainring teeth - because the chain is stretched.

On top of what's been suggested, check your chainring for bent teeth. Change your chain. If it then rides like a pig and sounds like an old blender, you've left it too late and will need to change your chainring and cassette too. These are consumable, not warranty.
 

Carlos85

New Member
Mar 8, 2021
3
1
Leeds
Cheers guys thanks for replys yea bike shop is good so im sure it will be sorted. When I took it back he measured the chain stretch and was well within tolerance. Hopefully just a bent tooth or clutch derailer but to much of a coincidence that it happend 50m after the update. They told me be ready for Thursday with fresh mt7 pros on so IL see what the out come is and post back ?.
 

Mikerb

E*POWAH Elite World Champion
May 16, 2019
6,105
4,636
Weymouth
That bike has a chain guide so the only 2 reasons I can think of why the chain would come off the chainwheel is the rear mech left in service mode ...which you would surely notice!............or a loose chainwheel......which is not uncommon for direct mount chainwheels not correctly fitted.
 

lightning

Well-known member
Apr 5, 2021
715
409
UK
Well, the O/P has never been back since posting the above, so we'll never know why his chain kept coming off.
 

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