Bicycle Mechanics - Chain ring questions

I am thinking that all I need is a large ring of 46 teeth. I have the standard crank with 130 mm bcd spacing. So if I have a 38 small ring which is as small as the 130 mm bcd will work and a 46 large ring I am thinking that this will be the best setup for me. My bike is a 7 speed.

So if I want to buy the correct chain rings what do I need to know and what do I need to take into consideration. Will I have to change the front derailer to get it to work with a 38 46 chain ring combination?

Straight forward swap. It's best if the outer chainring has shifting aids and the inner doesn't, like your current chainrings likely have. You may want to lower the FD a bit.

38-46 is one of the standard cyclocross combinations. Worked pretty well for me on a hybrid with an 11-34 cassette.

If your frame has a "braze-on" type FD hanger you probably won't be able to lower the FD enough. If the seat tube is round and the FD is a clamp-on type you should be able to get it low enough.

Can an inside chainring be used as an outer chainring? Some of the chainrings on e bay don't specify if they are inside or outer chainrings.


Straight forward swap. It's best if the outer chainring has shifting aids and the inner doesn't, like your current chainrings likely have. You may want to lower the FD a bit.

Can an inside chainring be used as an outer chainring? Some of the chainrings on e bay don't specify if they are inside or outer chainrings.

Yup, do it all the time.

Thanks

Now I have another question. Will a fixed gear chainring work as an outside ring? The fixed gear chainring appears to have an inside circle of metal that goes between the 5 bolt holes which I guess would make the ring stronger. I am not sure if this ring of metal would interfere with the crank arm attachments or not on a road crank.

The fixed gear chainring does have 130 mm bcd.

Now I have another question. Will a fixed gear chainring work as an outside ring?

Probably not. A fixed gear chainring (or cog) is likely to be made for 1/8" chain, not 3/32" (although it should specify.) If it's made for 1/8" chain, it will definitely not work. Even if it is meant for 3/32", it will have taller teeth so the chain doesn't derail when used on an SS/FG bike. This means you might not be able to shift on or off the ring! Stick with a road ring.

http://www.sheldonbrown.com/harris/chainrings/130.html

The fixed gear chainring is a 1/8" so it wont work.

Thanks again for all the good information.

I had a 42 tooth gear laying around and I put it on for the big ring. I can now ride the big ring just about anytime that I want to. I don't know what all the fuss is about riding in the big ring. :)

I ride about 15 mph on flat ground so the 42 and a 17 gear is probably going to do just fine for me.

The gears shift fine one the bench and in a few days maybe I can do a road test. I did my hill ride today using the 38 and 28 gear and it seemed to be perfectly matched to my strength and the hill that I ride. I had my best time on this hill today. I have used lower gears which I guess were not challenging me enough and my time was slower.

Thanks again for the help. I now have something to play with and see how it will work for my type of riding. The 42 chainring is not a big jump in gear inches but it does help with chain line and it helps to reduce cross chaining.

So wait.. you're running a 42/38 double? The difference is so close, there's hardly a point to having both rings. You probably just have a bunch of duplicate ratios. IMO, you'd be much better off with a compact (110 BCD) crank running something like 42/34 or 44/34. You'll have lower low gears without losing anything you have now.

Will a fixed gear chainring work as an outside ring?

Something like a Surly Stainless steel chainring?
not track 1/8" chainrings..
Surlys , they are thin enough , if you want snappy shifting? the
outer with shifting pins would be better
!/8" chain will be clunky 3/32 a better choice aka 5,6,7,8 speed chain.
Surly SS are flat, and can be flipped to double the wear life..

i see

i see

Glad we could help. Welcome.

I finally got to try out the chain rings today. They shifted very well and didn't even drop the chain. :)

The 42 is all that I need for now. When I get stronger, then I will probably want a larger ring. I even climbed a little grade in the 42 thinking that I was in the 38. I think that when I start spinning out the 42 on level ground I will consider going bigger. So I may never go bigger if I can increase my cadence enough that I can't spin out.