MTB - Bontrager crankset query - fun with front cogs ...

[Radchenister]

... well perhaps not much 'fun' actually, apologies for attention seeking!

I'm trying to sort out an issue on a friend's bike, they've seriously bent the middle front cog and I'm a little out my depth on the spec' front, so some help and input would be appreciated if possible please.

Aiming to replace the middle cog on one of these bikes:
http://www.bikepedia.com/QuickBike/BikeSpecs.aspx?Year=2002&Brand=Trek&Model=4900 WSD&Type=bike#.UTI7cKKvZ8F

...and think this appears to be a viable and cost effective option(?) but is not the cheapest available; we're not after bargain basement, just a good equivalent to what's on there at present, it seems that Bontrager / Truativ replacements can be a bit fickle (from what I've read) and I'm wondering if this one will suit?:
http://www.amazon.co.uk/Truvativ-Chainring-104mm-Aluminium-£22-49/dp/B004C963FQ/ref=wl_it_dp_o_pC_S_nC?ie=UTF8&colid=18WQPQ4S8B7FR&coliid=IGEH49YD783AH

We're inclined not to worry too much about the gearing change from 34 to 36, as the rider is light and fairly powerful but do wonder if it's the right one generally and are there any other makes / options?

Any pointers appreciated.

Crankset:

Seriously bent middle front cog (beyond bending back?):

Close up of cog:

 

[gwhite]

It is possible to straighten these. There is a tool for the job but it can be done with a large Adjustable spanner. Stand directly above the ring and rotate the cranks until the bend is visible. Gently bend the ring until all looks straight.

 

[Radchenister]

Not sure I want to bend it while still on the bike, particularly as it's the middle ring. I might take it off and have a go in the vice - thanks for input.

 

[mickle]

Or replace the individual ring.

 

[Radchenister]

That was the original idea, as per the link above; I was after a thumbs up on choices or any pointers as to what would fit - I have read that there are some compatibility issues elsewhere but no-one on various forums has shed much light for the questions posed by others, so I might just wing it (if no-one can say for certain).

 

[mickle]

Its a four bolt middle ring of 32 teeth. Steel. Eight speed I presume. They're easy to find. Every bike shop has one in a drawer.

 

[Radchenister]

What I'm really asking is are they a standard product compatible across different makes or are there subtle differences to watch out for?

I was after an internet order but if it's a bit tricky then I may well have to head for that bike shop.

 

[mickle]

Its a standard part.

 

[Radchenister]

Thanks.