Making my cyclocross gearing more road bike

[nrosko]

Purchased a bike on a whim in an effort to get fit again. I went for a cyclocross 'cannondale caadx tiagra'
because realistically when out-doors it will be a mix of road & trails. For now i want to use it with a smart trainer & use trainer software. I would like to use swift for racing as something to motivate me.
Am i better going for a different gearing setup? I understand that cyclocross has lower gear ratio & thought maybe for the trainer i should use something else. I will need to get a cassette anyway for the trainer. I find it difficult to understand if its possible to do this. I know i have to choose 10 speed but that's about it. is it even worth doing this anyway?

 

[stumpy66]

I don’t have a smart trainer but my understanding is that the trainer will control the resistance so the gearing on the bike doesn’t really come into it, choose a gear that gives a straight chain line.

 

[Spiderweb]

I wouldn’t waste your money, there won’t be that much difference than with a road set up.

 

[nrosko]

I don’t have a smart trainer but my understanding is that the trainer will control the resistance so the gearing on the bike doesn’t really come into it, choose a gear that gives a straight chain line.

I guess i've not really thought about this but i imagined dropping a gear to climb a hill or using upper gears to gain speed on the flat & downhill sections.

 

[nrosko]

I wouldn’t waste your money, there won’t be that much difference than with a road set up.

It wouldn't really be a waste if its just a cassette as i have to buy one to use with the trainer. Im just not sure if i can stick any 10 speed cassette or stick to specific size.

 

[Spiderweb]

It wouldn't really be a waste if its just a cassette as i have to buy one to use with the trainer. Im just not sure if i can stick any 10 speed cassette or stick to specific size.

I think your rear cassette on the Caadx cross bike is 12-28 which is probably the most common cassette used on most road bikes too. The difference with a cross bike is usually the cranks being 46/36t where a road bike is mostly 50/34t.

 

[boydj]

The gearing you have will be fine for now. If you find it too easy, even on the highest gear, then push up the resistance level on the turbo. I'd be surprised if you could not find a level that you struggle to turn over. You should be looking at getting your cadence up to a minimum of 80rpm to make the most of your pedalling efforts to test your heart & lung fitness as well as your leg strength.

46x12 is probably good for over 30mph with a reasonably fast cadence, so should be enough for most non-competitive cyclists.

 

[nrosko]

Thanks for the replies, i'm starting to get my head around how it works a bit. The thing with upping the resistance is i imagine that's not what you might do in a race in zwift. Remember that was part of the motivation so i could compete a bit in races on the turbo.
But i think you are right i'm just going to stay put i'm thinking way too far ahead. I'll just get the same cassette for the turbo.

 

[Tigerbiten]

46/12 on 700/35 wheels is a 104" gear, which spun at 80 rpm is 27 mph on the road.
That should be fast enough on a trainer but I'm not sure how the effort needed ramps up due to lack of wind resistance.

On the road, wind resistance goes up at the square of the speed and really kicks in above about 15 mph.
So the effort needed goes up at the cube of the speed, which is why around 30 mph is about as fast as you can go on a standard bike.

 

[nrosko]

So wheel size comes into play, i didn't even think of that. Just out of interest is it relatively simple to fit a bigger crank in regards to selecting the correct product?

 

[Tin Pot]

Gearing is irrelevant on a turbo trainer.

Get training!

 

[boydj]

So wheel size comes into play, i didn't even think of that. Just out of interest is it relatively simple to fit a bigger crank in regards to selecting the correct product?

Crank length is not really relevant to the gearing of the bike, given that there's only 10mm of difference in crank lengths in different sizes of most models - 165mm to 175mm (and 165 is relatively rare).

 

[Tigerbiten]

Gearing is irrelevant on a turbo trainer.

Get training!

The OP want's to use his turbo trainer to 'race' online against others on their turbo trainers and is worried that his bike is under geared because it's only a cyclocross 'cannondale caadx tiagra' and not a full allout road bike.
Whereas the only gears he's really missing versus full allout road bikes are the ultra high +100" gears which are only really useful for silly fast downhill runs.
Unless you have a naturally slow cadence, you'll never use a +100" gear on the flat as it tends to put too much strain on your knees.
You're much better spinning around the 75 rpm range and as you get fitter then you'll be able to hold a higher cadence for longer, so don't go mad right from the start ......

Gears.
The english method to measure gears is ......
The number of teeth on the front chainring divided by the number of teeth on the back sprocket multiplied by the wheel diameter in inches.
Normal range is ~100" to ~30".
MTB will have a lower first gear and road bikes will have a high top gear.
I think most 'standard' bikes nowadays are overgeared as it's fairly normal for someone to ask how to get a lower first gear, while it's very rare for someone to ask how to get a higher top.

 

[Tin Pot]

The OP want's to ....

...quoting the OP is not a response to my post.

One of us is missing something here. You can set the resistance on turbo trainers. Gearing is irrelevant.

https://zwiftblog.com/using-the-trainer-difficulty-setting-in-zwift/