[Closed] Compact road gearing question

That would shift OK but leave you spinning like a nutter down hills.

Not tried it but why would the shifting be bad? It's less of a jump than a normal compact

46-11 is plenty for me on downhills!

I'm more interested in the low end

I have an old trek that came with 36/46 as standard, shifted fine with a double STI, I imagine yours would too if it currently has a 34/50 and appropriate mech fitted.

I've read it's something to do with the way the teeth of the two rings are aligned?

46-36 OK
46-34 not OK

Nope they're wrong, 46-34 would be/is fine.

Go Ahead.

Good range for climbing that or bumpy terrain.

I think I have a 46 at the front, I don't spin like a nutter down hill, it means I can utilise the big ring more often than before..

Pretty standard cyclocross gearing is 34/46 or similar.

That would shift OK but leave you spinning like a nutter down hills.

It's not that bad @90RPM 50x11 is~32MPH, 46x11 is still 29.4MPH
and 90RPM isn't that fast, if you can crank up > 110RPM+ you'll be well up to the point of tucking and freewheeling or at the end of the hill before long.

Good hilly terrain gear choice for non-racers or anyone carrying anything.

I have 34:46 on my CX bike and that is fine.

It is a little spinny on descents but only after you get above 30mph. For general riding it is fine, I use that bike as my winter road bike.

Can be a little frustrating on some of the longer down hills where others can pedal and I just have to tuck up - but unless you are racing it just means you reach the bottom a few seconds later - no big deal.

If you aren't using the big ring in a 50t much then it could work. I end up riding everything in the big ring on that bike as I have a 30t on the back and generally don't tae it out into proper hills.

Depends on the chainrings, shimano clock all their rings so the teeth/ramps/pins/cut outs and suchlike all align properly at the points you are most likely to achieve a shift.
Using the wrong ring (a type A instead of B, or a non-shimano ring) can cause issues when the chain drops on to the tip of a tooth, instead of into the gap between teeth. It doesn't always happen, but when it does, its a pain in the arris. You can clock the inner ring (on a 5 arm it's easy) and hope that you get a more favourable alignment.
I had a 53/40 combo that refused to downshift, it ALWAYS skated over the top of the teeth, unfortunately, clocking a 40 makes no difference (and clocking the outer moves the catch pin which is unfortunate), changing to a 39 fixed it instantly.

But, you might get a nice combo straight off the bat.

Why have you posted this twice?

Personally I'd avoid the faff and go with a 28 tooth cassette which will work with a short cage rear mech. My Utergra 34/50 + 11-28 combo gets me up anything. Probably the lowest you'd want to go on a lightweight road bike.

Personally I'd avoid the faff and go with a 28 tooth cassette which will work with a short cage rear mech. My Utergra 34/50 + 11-28 combo gets me up anything. Probably the lowest you'd want to go on a lightweight road bike.

True, but the 16T gap between the rings is really annoying.

It's not that bad @90RPM 50x11 is~32MPH, 46x11 is still 29.4MPH

Problem with this is that 11t is blooming useless, it's almost just a spacer. Even pros with decent mechanics seem to have problems with jumping chains on the 11t. I certainly wouldn't be using it on a regular basis.

46-11 is plenty for me on downhills!

True, but the 16T gap between the rings is really annoying.

6800 is so slick I enjoy changing gear more often.

Problem with this is that 11t is blooming useless, it's almost just a spacer. Even pros with decent mechanics seem to have problems with jumping chains on the 11t. I certainly wouldn't be using it on a regular basis.

Running a small ring / small sprocket combo on Shimano 11 speed groupsets is a crossed chain, big ring + smallest sprocket is fine. Have a look at the chainline next time you have a 6800 or 5800 equipped bike in front of you.

6800 is so slick I enjoy changing gear more often.

Shift quality isn't the issue: you have to change two or three cogs at the back at the same time to maintain cadence.

You could virtually spin that out on the flat.

Downhills? You could virtually spin that out on the flat. A 46t front for road riding would be too low for me, especially on a lightweight bike ridden in a bunch.

Rubbish I'm afraid. 46x11 gives 112 GI whereas elite team pursuiters use a lower gear than that to average over 60kph.
I've used my cross bike on slicks with a 46x11 in flat E12 crits occasionally and have always managed to figure in the sprints.

OP, I think you'll find it will be OK as it is an even tooth jump which is what both rings will have been designed for.

EDIT: cross post with Rusty

I like 50-36 ,which I hear they are now naming the [s]next big thing[/s] semi-compact 🙄

For the hour record Wiggins used 58 x 14 = 108.9"

1) the track is essentially flat
2) his gear selection is a compromise as he has to ride fixed from a standing start.
3) Wiggins has one of the best pedalling actions out there
4) He still isn't using a 46 x 11 for a good reason.

There is more to it than looking at gear inches when selecting you setup.

He still isn't using a 46 x 11 for a good reason

34 46 i a good combo for me. I spin quite quick, i'm not that fast (think audax not race) and i don't like the big gear jump that 34/ 50 gets you.

shimano do make a 34/46 chainset, i think it's sora CX one; just to point out that it is not that weird.

but you said:

You could virtually spin that out on the flat.

Which is demonstrably b0ll0cks, as per above comparisons with track, and the fact that 'spun out' (what RPM do you spin out at?) at 120RPM 46x11 would be giving you almost 40MPH on the flat, if you can keep up 40MPH on the flat for any significant time then you shouldn't be wasting your time posting on here, you've got bike races to win! It might be [i]possible [/i]to spin that out on the flat, briefly, if you're very strong and fit, but it's hardly a problem most people will face.

Which brings us back to

Good hilly terrain gear choice for non-racers or anyone carrying anything.

As it doesn't sound like the OP is asking for gearing advice for grand tour or bunch racing does it?

And downhill once you're up to >40MPH you're probably going to get more benefit from a decent aero tuck and freewheeling than anything else, if you're that way inclined, but again, it doesn't sound like the OP is asking about top end racing gearing does it?

I'm also more than a little sceptical about your 11T being useless comment as well, there is no reason a well adjusted and maintained drivetrain won't operate skip free on the 11T under [i]normal use[/i].

4) He still isn't using a 46 x 11 for a good reason.

There is more to it than looking at gear inches when selecting you setup.

no doubt or argument there, but again, I don't think the OP was asking about gearing advice for his next attempt on Wiggo's record, he's asking about normal gearing for normal riding, specifically the shifting performance, not suitability of ratio, and where a 46T ring will probably be more than adequate, and you know what, if he gets stronger or moves somewhere flatter I'm sure he'll be able to put a bigger ring back on, but frankly your comments are of no use to the OP at all.

Shift quality isn't the issue: you have to change two or three cogs at the back at the same time to maintain cadence.

Which is really easy. I have it stored in muscle memory now.

Which is really easy. I have it stored in muscle memory now.

If you say so. I think having to do four separate clicks to maintain a steady cadence is a bit irritating. There's also the issue of a 36T inner being a bit "betwixt and between" - when I used to have a 42T middle with a 12-25 block I could pretty much leave it there on slow social rides.

Thanks for all the replies. As a fat forty something I'm not too concerned about keeping up with Bradley Wiggins! My main question was whether changing the 36t inner for a 34t was likely to cause problems when shifting to/from the 46t outer - I will give it a go.

Cheers!

Hi,

Running 46/34 front with 12/30 cassette with no issues whatsoever.

FSA crank with Shimano/FSA chainrings. Rest is various Shimano bits - Sora front mech, Tiagra rear mech, Ultegra cassette, 105 shifters and SRAM 1050 chain for a good measure...

Cheers!
I.