Gear ratios query

Muckers

While running a 50/34 compact chainset with a 12/28 cassette, what would be a similar gear ratio while using a 1x chainset?
Thanks in advance

Eamonnator

A 46 chainring with an 11/40 cassette might suit.

boomdocker

50/34 with 12/28 gives a range of 4.17 (hardest gear) to 1.21 (easisest gear)

I did this conversion this year for cyclocross racing - so was mainly interested in making sure I replicated the easiest gear
I was working from a 40t chainring - so a 34t cassette gives me 1.18 for the easiest gear. 32t would be slightly too hard - losing 1 gear at the top end. So I settled on 34t cassette
At the other end I have a ratio of 3.33 (40 x 11) compared to 4.17 (50 x 12) so losing quite a few gears - but as I said for my setup I'm not too concerned

So depends what you want to do?
You can play around with different size chainrings obviously and wider ratio cassettes - make sure though if you are doing a 1x conversion that you have a derailleur with the correct capacity
Also make sure your frame can take the size chainring you need. For mine (Giant TCX) I was limited to 40t due to chainline issues

I use this to calculate the gear ratios: https://www.bikecalc.com/gear_ratios

Hope that helps!

Muckers

boomdocker wrote: »

50/34 with 12/28 gives a range of 4.17 (hardest gear) to 1.21 (easisest gear)

I did this conversion this year for cyclocross racing - so was mainly interested in making sure I replicated the easiest gear
I was working from a 40t chainring - so a 34t cassette gives me 1.18 for the easiest gear. 32t would be slightly too hard - losing 1 gear at the top end. So I settled on 34t cassette
At the other end I have a ratio of 3.33 (40 x 11) compared to 4.17 (50 x 12) so losing quite a few gears - but as I said for my setup I'm not too concerned

So depends what you want to do?
You can play around with different size chainrings obviously and wider ratio cassettes - make sure though if you are doing a 1x conversion that you have a derailleur with the correct capacity
Also make sure your frame can take the size chainring you need. For mine (Giant TCX) I was limited to 40t due to chainline issues

I use this to calculate the gear ratios: https://www.bikecalc.com/gear_ratios

Hope that helps!

Very detailed reply and thanks for your help. Yes it's a 1x conversion. Didn't realise the chain ring size fitting the frame could be an issue

boomdocker

Muckers wrote: »

Didn't realise the chain ring size fitting the frame could be an issue

You should be fine as long as you use a chainring big enough to replace your current outer ring - as Eamonnator suggest - 46t will do the trick

I was trying to use a much smaller mtb style chainring - I should clarify what i was trying to do - which was use the smallest chainring I could get away with

Muckers

boomdocker wrote: »

You should be fine as long as you use a chainring big enough to replace your current outer ring - as Eamonnator suggest - 46t will do the trick

I was trying to use a much smaller mtb style chainring - I should clarify what i was trying to do - which was use the smallest chainring I could get away with

I was hoping to maybe fit a 42t chainring with a 12/36 cassette. No idea whether that would do thd job for me

boomdocker

It should, with the 42t fitted in the place of the 50t ie on the outside
As I said above, you'll need to make sure you have a rear mech with the capacity you need