Chainring sizing

[onb]

If I currently run a 30 chainring with a 29 cassette ring whate the equivalent casstte size needed if my smallest chainring becomes a 34 ,I just need an equivalent I have looked at various websites which just blind me with science.

 

[gavintc]

If you change nothing on your bike except the chain rings and the cassette , you can do a quick calc by dividing 30/29 as that will give the number of turns your back wheel goes around for every turn of your pedals = 1.03. Using using this ratio and assuming you have a 34 chainring suggests you need a 33 tooth cassette to replicate the ratio.

 

[T4tomo]

So you're virtually 1-1 so a 34 or 33 biggest sprocket would do it. Do either exist? I think the old mega range cassettes had a 34 sprocket. You can defo get a 32 biggest sprocket. You may well need a bigger capacity rear derailleur though.

 

[cyberknight]

@Nigelnaturist is your number cruncher .

 

[Nigelnaturist]

@Nigelnaturist is your number cruncher .

If I currently run a 30 chainring with a 29 cassette ring whate the equivalent casstte size needed if my smallest chainring becomes a 34 ,I just need an equivalent I have looked at various websites which just blind me with science.

I am wondering why you need to change from a triple to a double.
I assume your on a Campy set up, there are both 9 & 10sp 34th first cogs and a 32 11sp Campagnoloa 42th SRAM 11sp other options out there as well, but would need to know your current set up.

 

[onb]

Yes you are correct it is campag , I have been away on holiday and hired a compact equipped ShimaNO cycle and I mused with swopping from triple to compact double however a couple of hours out today have made me wonder as well why do I need to change .

 

[Nigelnaturist]

@onb I love my triple I have so many possible options you just don't get on a double.

 

[Grant Fondo]

28 front 32 back for me...beat that!

 

[spiderman2]

28 front 32 back for me...beat that!

specialized sirrus 26 front 32 rear

 

[gavintc]

specialized sirrus 26 front 32 rear

But that was not what the OP asked for.