Inner chainring bent on 6 week old MTB

Question

I bought a new Voodoo Bizango 2015 6 weeks ago. When I was out earlier I changed down and the chain somehow got wedged between the 2 front chainrings (It's 2x10) and bent the inner ring. I've read on here that this just shouldn't happen unless the chainring was a bit dodgy.

Do you folks think Halfords will cover the part or should I just bite the bullet and get a new chainset? I went into Halfords earlier but have to book the bike in for next week....i'm not very patient :)

Alternatively, I've been trying to find a replacement chainring. How compatible are these? The chainset is SR Suntour CW-XCM-D 22/36T. I'd prefer to go this route so I can buy a couple of them in case it happens again. I can't find the Suntour chainring but there's plenty of Shimano 22T 64BCD online, I'm just not 100% if they will be correct for the bike.

Here's the badness

zipzit · Accepted Answer

This could have also been a loose mounting bolt causing the excessive gap.  So here's the way warranty works.  The bike shop looks at your bike.  They make a recommendation to the manufacturer about what caused the defect.  If they believe it was

loose bolts on the small sprocket from the factory
slightly bent sprocket from the factory, made worse by the chain falling off 
wrong chain used for the application (8,9,10 + sprocket chain width)

and they manufacturer says yes, they will re-imburse your local bike shop for the repair then you have a winner.  In some cases the manufacturer says no, they didn't cause that defect.  In that case the bike shop could build goodwill with you by repairing it at their cost to keep you as a happy customer. Talk to your bike shop.  DONT touch the area with tools at all (let the bike shop to that as part of fault assessment...)  Work with your bike shop to come to a resolve that makes everyone happy.

If that fails, and the bike shop says sorry, you are out of luck in obtaining a free repair there are always other options.  If you are a do it yourself person, you could remove the right side crank, remove the small sprocket, and bend it flat again (if its steel).  If its aluminum, toss it and get a new sprocket.  They really don't cost very much.

Chris H · Answer

A chain shouldn't even come close to fitting between the chain rings if all the parts are selected to work together. Either the bike was built using badly matched components or something was wrong (bent) to start with. I suspect the latter as that's a chainset for 10 speed chains - unless that was specified but a different model was fitted in error.

It's hard to see how you could bend only an inner chainring inwards accidentally.

Criggie · Answer

What happened at the moment it bent?  Were you in a super low gear and booting the pedal down?

You said earlier its a Halfords bike, which to me is a BSO made of cheap metal for the lowest price.

Is this it?   http://www.halfords.com/cycling/bikes/mountain-bikes/voodoo-bizango-29er-mountain-bike   Curiously its priced well above the normal level for discount bikes.

I'd put it down to one or more of

Your leg is too powerful for the cheap bike
Your chainring was extra weak right there
There was a stone or stick jammed in the chainring that made the chain only partially mesh.
The bike was momentarily in a hole or caught on a lip
You were going uphill strenuously
Chain was loose and slapped to the left, missing a tooth

Since its 6 weeks old, this should be covered by warranty.  Take it back and politely request your consumer rights.  *varies by location of course.

Are you over the maximum permitted weight for the bike?  This might void your warranty, as could "riding this bike off-road or stunting or jumping"

Did you self-assemble or pay the shop to do it?  This could also void your warranty.

DWGKNZ · Answer

The front mech may have been  misaligned and you've applied weight at a moment when it's not fully shifted. Your weight has bent the chain ring.

I have bent a SR Suntour chainring in a similar manner.

Halfords have grounds to say it's a user vs a product issue and may not replace it. Depends on the store and the sales person on the day or how hard you're willing to fight it really.

However, reading reviews on the 2015 Voodoo Bizango, it appears to be a decently spec'd bike on a really good frame. The SR Suntour crankset looks to be a weakness so you should consider upgrading to a better crankset. Even if Halfords replace it it'll still be a weak point on the bike. You can generally get well priced shimano deore level cranks or similar SRAM crankset which would be a good replacement while not over spec'd for the bike.

Inner chainring bent on 6 week old MTB

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