Ericoschmitt

Hello everyone!
I've bought this Athena 3x11 groupset, with 30/39/52 chainrings, but i find the middle is too close to the small (2 countershifts in the rear the next gear) and too close to the big (4 countershifts) when using 12-29 cassette. My current setup is an Ultegra 2x10 39/53 12-25 and when I ride solo I spend a lot of time between 17 and 19 cog (a bit crossed) and also 39-14 so there's a lot of unnecessary front shifts.

So I went to bikecalculator and found out my ideal middle ring is a 46, as I get a nice avg speed in the middle cog (straight chain), and would ride most of the time in the middle ring. A 44 would make it fine too.

My questions are:
1)Will the derraileur be fine when shifting from 30 to 46?
2) Can I install a campy CX chainring (outer) as my middle ring? It's the same 135mm BCD. It has shifting pins inside.
3) Or I could instead get a TT 44t inner ring, but that doesn't have shifting pins inside.

Any other options? Maybe TA? 10speed rings?

Thanks!

rpenmanparker 

First off, your preferred gear combinations using the 17 and 19 cogs isn't crossed at all. It is pretty much right down the middle. And why would you switch to 39/14 when you could stay on 52/19 which is nearly identical?

With modern double front derailleurs a 16 tooth ring difference is the advised limit. Hence the popularity of the 34-50 and 36-52 combinations. Assuming your triple is speced similarly (you can check it online I imagine), you should be okay.

Unless you have synchronized electronic shifting, though, I don't think your idea is the best approach. Ideally one doesn't go back and forth on the front with mechanical shifting to hit every possible gear combination; you stay on one front ring or the other as much as possible. In order to do that and not lose a lot of gear possibilities to overlap, you want the two rings to have significant separation. And in order not to have extreme cross chaining, you don't want that separation to be too great. Hence the popularity of the 39-53 combination of rings. So you run up or down one ring, then shift to the other at the point they overlap and run up or down that one.

Your plan will make the two gear runs so similar, that there won't be much use to having both of them. Basically the separation between rings will be nearly the same as the separation between your favorite rear cogs. That means you will only get one new gear combo by shifting the front. Of course, having the near-granny third ring will alleviate some of this problem, but still, I don't think it is a good plan.

seypat

Rpenmanparker is giving you good advice. The main advantages of a triple is staying on one ring for long periods of time and not having to surf the entire cassette to find a gear. That is why the overlaps are there. Once you get to an overlap then you can shift and stay on that ring for a long time going up or down as necessary. You ride in ranges and loops. Ride on one ring, up or down 5 or 6 gears then you shift to another ring. Ride on that ring up or down until you run out or gears one way or the other. Then shift again. You may go back to the ring you were on. Then the same loop/sequence repeats itself. You also get to keep the standard double which is great for general riding. I may go a week or two without going on to the granny. I also have rides that the 52 big ring is seldom used. I loop between the middle and the granny or the big and the middle. I have one ride that I made up a 50/36/28 crank for. That is a 100 miler that I'm on the 50 for maybe 25-30 percent. The granny sees the most action on that ride. I run 3x5-8. With 11 cogs on back you should be able to stay on a front ring for long periods of time. You might even go complete rides staying on one ring.

Ericoschmitt

I understand your advice to stay longer in one ring, and thats exactly why I want a bigger middle ring.

Most of my solo rides in flats vary from 30 to 35km/h. If i get faster than 33km/h on the 39t, I'll hit the 13 cog, and thats crossed. If I'm the big ring and go below 31km/h, I'll hit the 21 cog, also reasonably crossed (3 cogs to go). That's why I'm eighter shifting the front often, or crossed.

On the other hand 30 is so close to 39 that its equivalent to only two shifts in the rear.

A 46t gives me a speed range from 21.5 to 39.5km/h at 85-95rpm without hitting the two highest or lowest cogs (7 central cogs only) and theoretically seems to be the ideal choice when looking at the numbers table.
So the thing is knowing if that will work fine for the shifter...

The big ring would still be used for faster/group rides, races and downhills. I would use a bigger one like 58t (with a 46), but it seems that the athena triple is for up to 52t.

seypat

That sounds like the old "Half Step + granny gearing. Look it up. There should be plenty of thread here on BF.

Sy Reene

Offhand considering it's a middle and centered ring the 13 maybe a useable cog. That said maybe putting on a 11-29 cassette would make the 13 more useable for the 39 ring?

I thought I've heard that campy designs their ring combos with specific shifting ramp locations and swapping in other size rings can affect performance. E.g. At one point I was considering changing my 34 ring for a 36 on my compact double and was advised against this.

HTupolev

What's your chainline actually like in the small-small region? Lots of doubles have the cranks offset a bit to the outside, making those ratios quite well-behaved.

I think you also might be overly worried about straight chainline if you're nervous about spending a lot of time in the middle ring of a triple with the chain offset a couple cogs off-center.
If anything, I consider a bit of such offset toward the small gears in back ideal; uphills require more shifting to lower gears than downhills require to upper gears, so it's best to be centered a little toward the higher ratios on the flats. Gives you more room to shift without changing to another ring.

Ericoschmitt

I have looked at the 11-29 cassette but dont like the gap between 15 and 17.

I knew camp cassettes had cogs designed for specific positions (as you have type A, B and C for most cogs), but never heard about that on chainrings.

I also heard that this Athena groupset is designed to support any gear combination, that doesnt mean it's good. I haven't installed it yet as I'm building a whole new bike, but based on my ultegra experience (which is basically the same, without 30t ring and 29cog), I get chain rub on the big ring if I go small small.

Ericoschmitt

Yeah, kind of. But half step was like.. 2 or 3 teeth difference. Nowadays that would be a waste as we have 1t cassette spacing.

I'd use a bigger big ring, but spec says biggest is 52. Unless I make some hack and fit a big TT ring!

Well id actually run a smaller granny and a corncob cassette, but BCD doesnt allow that to fit, so I got a 29 cassette instead... I do climb some serious hills that require that, or grinding 40rpm with standard setup.

As the outer rings cant be bigger or smaller, I can only change the middle one to fit my ideal cassette!... thats the drama.

Ericoschmitt

On my current bike I get some rub on 39x13 and a lot on 39x12. I'm having a custom frame built for this 3x11, and there's still time to ask for longer chainstays to avoid rub (and loose stiffness). That, or a bigger middle ring would do the trick. Too bad no one seems to have made that change around here to tell me if it works!

joejack951

If you can't use the full range of the middle ring without chain rub you need to work on your FD setup. As far as cross chaining, my advice is don't worry about it. On my 2x11 bikes (Shimano 105 and Campy Chorus) I use every single combo. I get some rub in the small/small on the Campy bike but it also has 135mm rear spacing (a known compatibility issue). If and when stuff wears out I'll replace it. Seems a lot easier than trying to hack together a crankset that will wear slightly less quickly.

rpenmanparker 

Yes, I don't get OP's fixation on cross chaining. It seems to be driving an unwise design plan.

Barrettscv 

Just use an entire 10-speed 53, 42 & 30 Campagnolo crankset. The 10-speed crankset will work perfectly with an 11 speed chain.

See: https://www.ebay.com/i/162518646994?...D1231084126667






.

Ericoschmitt

That setup would probably make me satisfied already. But 400 bucks... Ive already got the athena for less then 100!

Ericoschmitt

Well, maybe I'll just leave it as is for a while. I dont think the triple will have rub, but my double has even if I trim the fd.

Barrettscv 

You can find a 53, 42 and 30 Campagnolo 10-speed triple at all price points.

Ericoschmitt

Found my answer in this other thread:

https://www.bikeforums.net/bicycle-me...na-triple.html

Its not customizable, as the middle ring has some kind of triplizer to it. This sucks. I wish I had learned this before buying... But it´s still much better than a double!