4th Chainring?

[vbc]

Recently bought this Stronglight Impact triple chainset from Chainreaction and on delivery I noticed a small ring on the inside of the small 28T inner ring.

Any idea what this is, apart from a manufacturing fault that I can remove?

 

[TheDoctor]

Photo?

 

[02GF74]

maybe they forgot to machine the teeth?

is it something to stop the chain falling off the little ring?

photo would help.

 

[ianrauk]

a couple of weeks ago whilst commuting to to work. I saw a fella on what looked like a really old MTB. Low and behold I was amazed to see it had a quadruple crankset.

 

[mickle]

Recently bought this Stronglight Impact triple chainset from Chainreaction and on delivery I noticed a small ring on the inside of the small 28T inner ring.

Any idea what this is, apart from a manufacturing fault that I can remove?

It'll be to prevent the chain from dropping betwixt granny and bottom bracket shell.

 

[andrew_s]

It's deliberate rather than a manufacturing defect. All I can think of is that it's to stop the chain falling between the crank and the end of the BB shell if you drop the chain. No other granny rings have it, so there won't be any problem chopping it off if you want. You might save 5 grams.

At one time you could get a widget that bolted on in the place of the granny ring (74mm bcd) and allowed you to fit 1 or 2 freewheel sprockets in the place of the granny, giving a chainring down to 16T or so.

Here it is: http://abundantadventures.com/quads.html

 

[TheDoctor]

a couple of weeks ago whilst commuting to to work. I saw a fella on what looked like a really old MTB. Low and behold I was amazed to see it had a quadruple crankset.

I remember seeing one of those a fair few years ago. I remember thinking that if you had one of those going to a SRAM DualDrive unit, you could get 4*3*8 gears and it'd be...really confusing.

This was back in the days when 8 speed cassettes were the very latest thing.

 

[vbc]

Oops...forgot the link, see if this works.

http://www.chainreactioncycles.com/Images/Models/Original/43346-1.Jpg

 

[TheDoctor]

I reckon it's there to stop the chain getting wodged amongst the BB should it fall off.

EDIT - Like Mickle and others said before...