What do I need to go from 2 to 3 chain rings ?

[BADGER.BRAD]

Hello all,

My 20 inch folder has at present two chain rings but I would like to add a third as it is all up hill and down dale in this part of Shropshire So what do I need ? there is clearance on the frame for a smaller 32 tooth ring , The shifter with some adjustment will cope with it so it's just literally adding a chain ring .I'm guessing just extra fixing bolts and spacers but what are these called ? Probably not relevant but it is a 5 arm chain ring set up.

Thanks all

 

[DCLane]

You will need a crankset capable of triple chainrings, a triple left shifter and a triple front derailleur. It's likely you will also need a long cage rear derailleur and therefore also a new chain.

It's pretty much an entire groupset and it may not work on such a small wheel size.

 

[fossyant]

Might need a triple front shifter too

 

[Ming the Merciless]

Might need a triple front shifter too

That is what the triple left shifter is in post above yours.

 

[Ming the Merciless]

How about a touring double instead?

 

[fossyant]

That is what the triple left shifter is in post above yours.

We were writing at the same time. Only the one post when I was writing, then DC listed everything.

 

[Sharky]

What do you have now, in terms of chain ring sizes, it's BCD and cassette sprockets.

 

[All uphill]

Most folders with 20 inch wheels have a short wheelbase, so you may have trouble with achieving a decent chain line.

 

[BADGER.BRAD]

Might need a triple front shifter too

Not sure why but it already has this and the front mech is just restricted by the screws.

so you may have trouble with achieving a decent chain line.

I never thought of this , I'll have a look at the chain line at present from lowest to highest gear .

At present it has 52/42 as the front chain rings I have no idea if it is cassette on the rear but I will check it out, as the wheels are a little upmarket I'd guess it has. At the same time I'll check out the amount of teeth incase I could go for one of those mega range cassettes to give me the same ratios.

 

[BADGER.BRAD]

just to add at present it feels just about right on the flat ( could go a little higher) but on some of the hills I'm really putting some strain on the poor thing. Plus I was thinking of leaving my car the other side of the river and cycling too it at the start of the day and from it at the end,either way there is a really steep climb which I can just about do on an MTB but then I cannot fit a MTB in or on my little car. Plus I don't actually own one but sometimes use my lads,

 

[fossyant]

You are possibly trying to make a 20" folder do more than it's designed to do. How about a compact chainset ? You'll lose top speed, but hey, you can freewheel. You get some nasty chain lines with triples.

 

[wafter]

You are possibly trying to make a 20" folder do more than it's designed to do. How about a compact chainset ? You'll lose top speed, but hey, you can freewheel. You get some nasty chain lines with triples.

Only if you don't use them correctly..

 

[Paulus]

I would look at going either a compact chainset, something like a 50/40 or 48/38.
As @fossyant says, you'll lose a little top end speed but will be easier up the hills.

 

[Punkawallah]

Can you swap out the chain rings for something more forgiving?
Will your current bottom bracket take a triple chain ring?
Will the chain stays have clearance for a triple?
Will the chain line when on the outer ring of the triple make using it impractical, and would you be better off with a larger gear ring on the cassette/freewheel?

 

[BADGER.BRAD]

Will the chain line when on the outer ring of the triple make using it impractical, and would you be better off with a larger gear ring on the cassette/freewheel?

The chain line would have been terrible but I have just counted the number of teeth on the rear sprocket for the lowest gear which is 24, as it seems very easy to obtain cassettes with 36 teeth as the lowest gear I going to go with that and see if it is enough for my purpose. I have used these before on MTB based commuters but of course you still have another lower chain ring on the front mech , I'm not sure how this will compare with a bike with 20 inch wheels.