Sy Reene

So if you don't want to spend the money, consider just putting the "trainer difficulty" setting at 75%. A 36/25 combo at 75% difficulty I think is pretty close to what would be a 100% difficulty setting and having a 34/28 real combo to rely on.

banerjek

Your current setup has inadequate overlap and midrange -- my guess is you spend loads of time near the top of the 36 and the bottom of the 52.

If you're going to go with such a huge ring gap, you need a wider cassette. For starters, with a 10 speed setup, a 12-27 is a better combo because the cogs are exactly the same except the bottom 2 which you shouldn't be using anyway except when you need real low end.

If I were you, I'd drop the 52 to a 48 and switch to a 12/27 or 11/25 depending on how important the low gears are the next time you need a cassette. Consider taking the bottom ring to a 34 when you have to swap that out. This will give you better overlap and a very versatile range.

mstateglfr 

You went from 53/12 which is 116.24 gear inches to 50/11 which is 119.66 gear inches.

If you spin out now, then you were really spinning out before. The change actually should help you spin out less often.

f4rrest

Oh yep.

Might have been thinking of my other bike.

TCR Rider

That's an interesting suggestion. My first choice of cassette was 12-28 but I couldn't find that option in a 10 speed. I have a 12-28 11 speed on my other bike. I never considered dropping to a 48 I'll see how it goes with the 50 and take it from there.

raisinberry777

Shimano HG500 (Tiagra level) casettes are available in a 12-28:

wiggle.com.au | Shimano Tiagra 4700 10 Speed Cassette (11-25/12-28) | Cassettes And Freewheels

ksryder

As is the bikeforums way, everyone is getting hung up on the bits of your post that are irrelevant to the actual question, and instead of answering your question they're telling you that what you're doing is STUPID and WRONG.

No - no downside.

If it were me I'd change to a wider-range cassette first because that's cheaper, and then see if I still needed the compact gearing (because you'll probably need a new crank - 50/34 compacts usually have 110 BCD and I think 52/36 semi-compact uses some other BCD but I'm not sure.)

But if cost isn't an issue then you do you.

Esthetic

My trainer bike has a 53/39 and a 10 spd , 12-30 Ultegra 6700 cassette.

With a 10% max slope setting, i'm getting it done on climbing workouts with it. It's making me stronger for sure. Did a metric century in that bike with 2800ft elevation in Sept, whilst not in the best of shape, finished the event.

My Teammachine is 11spd 52-36, 11-32, so the idea is to get stronger on the trainer and be fine on the road bike with a gear and cog to spare on real hills.

Honestly the semi-compact is perfect, so if you need the extra spin just change the cassette and the rear derailler to a medium cage. In my case my 6700 Ultegra short cage RD is limited to 11-30 cassette with that particular arrangement, the hanger design, chain length, etc... plays a roll is how large you can go.

Sy Reene

Even cheaper is just changing the trainer difficulty setting on Zwift

generalkdi

Start with a 11-28, I'd stick with the 52-36 crankset.

beermode

I have a 12-28 10 speed SRAM cassette, pairs well with my ancient 10 speed Dura Ace.

jitteringjr

I can't believe this conversation didn't just end at the first suggestion of this. What a minute, forgot where I was. I guess never mind then.

tomato coupe

The OP seems to believe that increasing his cadence via lower gearing and increasing his cadence by changing the trainer setting is somehow different, even when pedaling at the same cadence and output power.

boulderist

OP, please listen to these people because the longer this thread gets, the more my head hurts.

To reiterate, as far as your hill climb efforts are concerned, there is no difference between lowering zwift difficulty and switching to a bigger cassette. Both of those options have the same exact result, which is that you'll need to increase cadence to maintain the same power as before.

pesty

Ignoring all the other stuff... If you're set on swapping out parts, I'd do this one step at a time. Switch to the 11-28 cassette first. You should be able to do that without making any other adjustments to the bike. I honestly would question how much of a difference you're going to see between a 34 and 36 chainring. You will however see a bit of a difference between the 25 and 28 in back.

If the cassette still doesn't do it for you, switch out the rings, but as others have mentioned, at that point you're going to need to adjust you're front derailleur.

Sy Reene

Truthfully there is a difference though. Changing the trainer setting, changes it globally. So for gradients, for example, in the 2-4% range, even if OP doesn't want or need help with gearing for those inclines, the trainer difficulty will make those easier as well, proportional to the difficulty percentage he chooses. That said, he can always gear up to a higher gear, but still the 'realism' to being on the road on a given gradient and in a specific gear, is still a bit off.

TCR Rider

Tell me something I didn't know. Yes resetting the trainer difficulty affects all aspects of the feel on the trainer. This defeats the purpose of using the trainer to prepare for riding in the real world. Everyone seems to be focusing on the cheapest solution but I'm looking for the best solution for me. I'm not adverse to spending a few bucks to accomplish this.
I was unaware that there was a Tiagra 12-28 cassette available and I already ordered an 11-28. What I plan on doing is dropping the 11 tooth gear and replacing it with a 16 tooth gear from a 12-25. This will give me the 12-28 that I'm looking for. BTW I use the 16 a lot so I would miss it. Hopefully this will make me happy. If not then I'll go to the compact.

tomato coupe

Switching to a wider range cassette also produces a global change. Changing the settings on the trainer (as originally proposed) is equivalent to installing a wider range cassette.

Realism? You're sitting on a stationary bike looking at a screen ...

TCR Rider

Snippy, snippy, snippy. Of course you are correct but at least in this case it's an interactive screen which does a far better job of providing a good workout than sitting on a dumb trainer and watching a movie.
But I digress, the purpose of this thread was not to weigh the pros and cons of indoor training but a simple question on gearing. Try to stay on point.

nycphotography

What grades do you climb when you ride outdoors?
What w/kg FTP?

TCR Rider

I currently live in a relatively flat area so no epic climbs just a lot of rollers. That's a big part of the reason I use Zwift to get in some climbing, albeit simulated. I do plan on relocating out west in the near future where there will be more substantial climbs. As far as w/kg I'm no wattage monster currently between 2 to 4 for the most part and my FTP is mumble munble I am still recovering from a knee replacement so there's that.

nycphotography

Found where you have 50/34 x 12-28 di2 for outdoors.

I would suggest 50x34 chainrings and a 12-28 cassette for the trainer. You should be able to find 10sp chainrings on ebay if you look a little. Meanwhile, the 12-28 cassette will get you half the benefit.

ALTERNATIVELY, IF your derailleur is mid cage, THEN I'd even consider an 11-32 10 speed cassette and keep the 52/36 rings. $20 on nashbar. Item: NB-CS10-132 And I think a tiagra rear der that fits a 34t cassette is $35 (chain reaction).

So $55 gets you done. Esp for a trainer specific bike.

Thinking about it, I'm kinda liking the 11-32 w/ Tiagra mid cage derailleur for the trainer bike.

tomato coupe

Maybe you missed the first part of my response:

TCR Rider

Good advice. Unfortunately rear der is not a mid cage but well worth looking into. Thanks.

nycphotography

$35 appears to buy one that is.