drilling Prait'xis chainring?

[djconnel]

My Praxis 46T ring came in very heavy: 103.9 g! I want to drill it out to bring it to a reasonable weight. It's a broad ring, so it's not obvious how best to do this. Has anyone done this sort of thing? Since I have neither tools nor skills, I was planning on taking it to a machine shop.



I doubt removing a bit of material will have a significant effect on shifting. On the other hand, the mental anguish over having such a boat-anchor chainring would be crippling.

[53x12]

Why mess up a perfectly good chainring? I thought people bought Praxis rings for reasonable weight, but more importantly their great stiffness and superior shifting performance. If you just want light, there are many other options out there. Aren't you concerned how your drilling will affect the performance of the rings?

[Ahillock]

+1. If you are looking for light, why not go Fiberlyte?

[djconnel]

The weight isn't "reasonable" -- their road rings are much lighter. This is a cross ring I want to use for the road. I want it for climbing hills quickly. It's obviously overbuilt for my purpose.

Fiberlyte are much more expensive with a fraction of the useful life.

[53x12]

I understand but the longevity will be dependent on how you use them and how well you take care of them. If you are going to use it for a climbing bike, you won't be shifting out of it too often. I think Stephen mentions he gets 6-7k miles out of his set of carbon chainrings, which isn't bad when you consider the weight savings (~60g) over the Praxis.

[LouisN]

DJ, please explain the benefit in weight/$$$/functionality/time consumed, by going this route ???

I would sell the chainring, and go Specialités TA Syrius 46T if money and durability is part of the equation...

Louis

[djconnel]

Cycling is a hobby. I don't worry so much about the time. In any case, weight is worth on the free market around $4-$5/gram. If I could save 25 grams off the chain ring, that would be worth around $80-$100. Adding in reduced durability, FiberLyte is more. Lost functionality should be negligible, since I'm not racing 'cross. Praxis is better because it shifts better than TA.

[Ahillock]

If you want lightweight and great shifting just pay the 40-45 GBP and get a Stronglight CT2 ring. Why distort the Praxis when you have no idea what that will do to the shifting performance? If the Praxis weighs so much to you, why purchase it in the first place?

[ferrarista]

I don't know how the chainring looks on the back side , but if you machine out the sections, you could take off the shifting ramps. That will degrade the shifting quality a lot.

Is it worth for less than 20 grams to mess up a good chainring? Ask praxis if they can make you a road 46T chainring. If not, I know stronglight makes a 46T outside ring in compact black.

[tranzformer]

What the above guys say. Don't mess with it. Just buy something else that you like the weight of better. I third the Stronglight recommendation personally.

[Rick]

It looks like you could have a machinist mill out some of the recessed areas.
But that will be expensive. Just take it to a credible machine shop and tell them what to want to do. They will make the precision measurements and setups.
The hard part will be getting a good symmetric pattern of material removal without hitting any essential "features" of the chainring.

[djconnel]

Anyway, I've been using Stronglight, and the shifting has been unimpressive. I bought it because all of the other sizes of Praxis are lighter and there were no available weights for the 46, certainly not from Praxis: they obviously decided to add substantial beef for the 46. Obviously the other rings shift quite well, so the beef isn't needed. Perhaps it's to avoid mud.

Surprised at the lack of support here, where people pay $1k+ to save 75 grams off frame weight.

[tranzformer]

My Stronglights shift like butta. Only weigh 120g (83+37) for my 53/39. Praxis still weigh more than that. Maybe you didn't have your bike setup properly when using the Stronglight rings. They are phenomenal.

It isn't a lack of support. People are just giving their opinions. Sorry you don't like the advice.

[ferrarista]

Try it if you want. I don't know what kind of support you are looking for. Its your money. You do what you want.

Like I said, make sure you don't take off the shifting ramps by machining the chainrings or else they will shift worse than stronglight or TA.

Since you want quality shifting, I don't know if its good to do that. Why not contact praxis and ask them? maybe they can make you a light road 46T. If you don't ask you won't know.

[prendrefeu]

Actually, DJ, I support you, and I'm also a little disappointed at the general mood in the thread.
What happened to tuning and experimentation? Is WW now all about people just buying and not tuning or experimenting?!
To hell with the warranty, make it your own.

If you can afford to mess with it, DO IT!!
Surely you don't need a milling machine to do the work, just a steady hand and patience with a rotary tool along with proper bits. That's it.

I would love to see how it comes out, and I certainly trust - and know - that you are intelligent in where you will be removing excess material so it won't interfere with the Praxis' shift ramps and pins.

DO IT.