Rubbing on outer chain ring causing gears to shift V2 Sofrider

[scoutie22]

Recently purchased lightly (200m) used Sofrider v2 and having issues with the chain rubbing against the outer chain ring while on the smaller chain ring and smallest (2-3) gears on the drive wheel. This causes the bike to change gears while I am peddling. As a new rider, this jarring to say the least. Have tried adjusting the derailleurs to no effect. Have read that I might need to put spacers between the large chain ring and the crank mount, but also a couple of posts on regular mtbs suggested issues with bottom bracket and/or gearing mismatches. Help? I am a cycling newbie, so please go easy on the terminology.... Is this common with the setup of these bikes?

 

[Charles.Plager]

Hi,
I no longer have the

Hi,

I no longer have the standard Sofrider crankset (I put on a 48/38/22 triple and new bottom bracket), but I did not experience what you're describing when I had the original crankset.

Can you flip the bike upside-down and see if you can duplicate by spinning the crank? Maybe post a video from your camera-phone?

Cheers,
Charles

 

[Andrew 1973]

Maybe a Bent Chainring

I know this would usually be obvious, but a chainring that is slightly bent is sometimes the culprit. The fact that you say the bike will change gears without shifting points to this as a possibility, especially with ramped and pinned chainrings, which have a lesser tolearance for misalignment.

 

[Charles.Plager]

I know this would usually be

I know this would usually be obvious, but a chainring that is slightly bent is sometimes the culprit. The fact that you say the bike will change gears without shifting points to this as a possibility, especially with ramped and pinned chainrings, which have a lesser tolearance for misalignment.

A good point. A video would show this (or, just flipping the bike over and looking carefully as you turn the crank).