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Small Chainrings... Which one to use???(5 posts)

Small Chainrings... Which one to use???FlySpinner
Aug 20, 2001 8:16 PM
Okay all you informed folks out there...

In a "Double" chainring setup, Which is best a 42 or a 39 ???

If you have an opinion let's hear it... Just try to support it and DO NOT take unnecessary shoots at others ability.

BTW... I ride a 42. Why? It came that way...

Sorry if any of you have seen this already in the Velonew Tech Talk forum.
re: Small Chainrings... Which one to use???Mike Prince
Aug 21, 2001 3:53 AM
I've used the 53/39 combo for years now. An airline incident this year caused me to buy a new big ring for my bike. Problem was that the shop only had the 53/42 Dura Ace combo. The tooth patterns are different on the A and B versions of the 53 and are specific to whatever small ring you are using. Anyway, I had little choice as I did not want to wait for the rings mail order.

I personally like the 42t small ring. FWIW, I have a 12-25 cassette and just like the different gearing that a 42 provides. There seems to be less of a drastic jump when I change between the 53 and 42. My other bike is geared similarly but has a 53/39. I do notice a little difference as the 39/25 gear is easier up the hills, but interestingly I make it up huge hills just fine with the 42 as well.

So, I plan to stay with my 42 now and when it is replacement time. One benefit is that with the 42 I notice less of a tendency for the chain to rub on the big ring in the 42/13 combo. Seems like the increased radius of the ring helps out my chainline a bit as well. Hopefully I have satisfactorily (sp) supported my opinion that the 42 is better for me.

re: Small Chainrings... Which one to use???Breezydz
Aug 21, 2001 5:50 AM
I use whatever chainrings I need to provide a straight block for the gears I use on flat land and easy enough gears to climb the biggest hills around here. You'll probably find that the drop from the large ring to the small one goes a little smoother with the 42, but if it takes away a critical gear that you can't get with the 39, use a 39.

For example I ride flatter terrain using 42x14,42x15,42x16,42x17 and will not give up any of them. I'm now 53 and couldn't climb that well 20 years ago either, so I've started using a triple and a 12-23. Once I got over the embarassment it's worked very well. Someday the 4 gear ratios I need will get a little smaller and I'll have to use a smalller chain ring or go to a 13-25 freewheel. Then I'll have to do both. Understand the theory but use what works in practice.
Chainrings are cheap, get both!!!Cima Coppi
Aug 21, 2001 5:53 AM
Personally, I ride a 39/53, but here in Colorado I need a 39 for the mountain climbs to be able to maintain a consistant spin. I have no problem using a 42 or larger on the plains where the hills are short and not too steep.

Good luck,

Thanks for the opinions...FlySpinner
Aug 21, 2001 9:19 AM
It has given perspective to the usefulness of both sizes.