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Discussion Starter · #1 ·
I'll be hopping on the trainer a bit more this year due to new baby in the house, for a trainer wheel do folks think it is better to use the same cassette you usually ride with or something else with less gaps?

52/36 up front right now with 11-speed Shimano 11-28.

I was thinking for trainer wheel to get 12-25.

Anybody have thoughts/advice? Definitely will be using a second wheel for trainer, lots of junky tires to burn through.
 

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I suppose it depends on the type of trainer. For a smart trainer and riding in ERG, it really doesn't matter. You could ride a single speed.

Unless you are doing really hard sprints or riding ridiculously high resistance, I can't imagine needing gears at either end of the range. I would think 12-25 is more than adequate.
 

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It matters very little. You set the resistance to about what you want with the chain in a middle gear, and just about any cassette will give you plenty of room to go up and down to vary it as much as you need. You're not riding varied terrain.
 

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Discussion Starter · #6 ·
Thanks, I guess I could have ignored the trainer part and just asked this: If you are riding on flat, unvaried terrain, does it really help keep things smooth to have as few >1 tooth jumps as possible? I realize that's a YMMV question. Anyway, likely going for the 12-25 or 11-25. Thanks.
 

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Less gap is better for flat riding and the trainer. However, look at the actual cogs and what you use on flats/trainer. The gap between the cogs you actually use may not be any different between those cassettes. Or not different enough to matter.
 

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I'd probably stick with the existing cassette. I have some low cadence climbing intervals that utilize my 53x11 and 53x12 a bit.
 

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A 36x28 is way too easy...even a 39x25 is so easy on any trainer that you'll never use it. Odds are a 53x12 is hard enough you'll only ever be able to use it on all out sprints on a trainer.

Rollers are another matter, which varies depending on the roller drum diameter....ofc rollers are much more fun.
 

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On my kickr i use an 11-25(10 speed cassette) my bike that is in there permanently is 50/34 in the front.

I would not go larger than 11-25 on my kickr because i use an 11-28 with a 52/36 on my jamis that i put a bulk of my outdoor miles.

Honestly for smart trainers depending on mode its in the cassette doesn't really matter.

ERG mode takes the gear changing out of the equation. The faster you spin the lower resistance goes, the slower you spin the higher resistance gets.

Sim mode: depending on your weight and trainer bought resistance can be as high as 24% or as low as 7%
Cycle ops hammer is producing a direct drive model now where it claims 24% graident based of 75kg rider weight.

Some trainers additionally have a motor in them which can propel riders down a 5% gradiant (tacx neo and cycle ops hammer)

Then there is the standard mode where trainers act as your typical fluid trainer with resistance profiles.

Wheel off trainers ship now with an 11-25 cassette(this gives a decent range for trainers).
 

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Like Jay Strongbow posted above, it depends on your typical trainer speeds.

You'd probably want close shifting in the 14 to 20 mph range. Maybe your small chainring would have the closest shifts there.

Here's a chart of speed vs cadence on a typical 34/50 and 11-28 in 11 speed bike. Note that the 34 chainring has close shifts all the way to 20 mph. (Here's that setup on Mike Sherman's Gear Calculator, 34-50 & 11-28 if you want to change cogs or use different cadences, the charts update on the fly.)
View attachment 314460

Using a 52 ring instead of 50 adds .6 mph at 15 mph, to about .9 at 25 mph.

My Kurt Kinetic fluid trainer is a good steady workout for me at 14-16 mph. ( I keep the chart handy, since it's interesting to see watts at different levels of effort.)

I would guess that your trainer is somewhat similar. In any case, you can get on it and see the speed where you are spinning easy, and the speed where you are pushing hard, and that's the range you want the closest shifts.

If you are at the 19-22 mph range a lot, it would help to have a 16 cog and an 18 cog. (It's common for cassettes to have 14,15,17,19.) To get the 14,15,16,17,18,19,21, you probably need a 12-25.

From Kurt, watts at different speeds. Fluid trainers have a predictable wattage that goes up dramatically at faster speeds. Kurt trainers are similar to riding up a 1% grade, not a flat road.
Mph Watts
13 110
14 126
15 143
16 162
17 173
18 206
...
22 319
26 473
30 675
35 1005

Thanks, I guess I could have ignored the trainer part and just asked this: If you are riding on flat, unvaried terrain, does it really help keep things smooth to have as few >1 tooth jumps as possible? I realize that's a YMMV question. Anyway, likely going for the 12-25 or 11-25. Thanks.
I really like close shifts on flatter rides. I'll trade off some close shifts for low gears if it's hilly.

I have the Abbey cassette tool that makes cassette swaps fast and easy.

To hang on fast-for-me rides, I've put on a 12-25 so that I have very close shifts at 20 to 24 mph, where I need all the help I can get. At 95 rpm, the speeds are 19.6, 20.7, 21.9, 23.3, 24.9 mph.

But at 15-20 mph or 25-35 mph, most cassettes are pretty similar. Those speeds are the 11-15 cogs on the two chain rings.
 

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Unless it's a smart trainer, you'll never need the bigger cassette. I have some low cadence standing intervals I do 50x11 and almost need to go with a bigger front for those, but not quite. Close spacing is important in my opinion to get the power and cadence combo you want
 

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Thanks, I guess I could have ignored the trainer part and just asked this: If you are riding on flat, unvaried terrain, does it really help keep things smooth to have as few >1 tooth jumps as possible? I realize that's a YMMV question. Anyway, likely going for the 12-25 or 11-25. Thanks.
I just stick with my existing cassette, no need to over complicate things.
 
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