Gearing Help

lesmond

Hi all,

Looking to add a bike to the collection and this time a CX variant.

Got my eyes on the Cannondale CAADX Ultegra 2016 (http://www.cannondale.com/nam_en/2016/bikes/road/cyclocross/caadx/caadx-ultegra-34271)

This is very similar to my road bike bike but I have just stumbled upon the SRAM Rival 1 series and am intrigued!

http://whyte.bike/gb/saxon-cross/

It looks great and what I have read it is very nicely suited to some CX riding!

Is there a scientific way of comparing the gearing at all? I'm concerned that I would run out of gears but could be totally wrong on this front!

Any other advice in this area appreciated!

wongataa

Work out the gear ratios available on each bike and compare them. The lower the ratio number the lower the gear. You could also work out the gear inches for each ratio on each bike but unless the bikes have different size wheels you only need the ratio lists.

lesmond

Is there an idiots guide on how to calculate the ratios?

The wheels look the same size to me on those 2 examples

trek_dan

http://www.bikecalc.com/gear_ratios

Bobbinogs

This one is about the best I have found. Tap in one, then use the Compare 2 Setups button.

lesmond

Awesome, that is great thanks!

So if I have done this right: http://www.gear-calculator.com/#KB=24,38,52&RZ=14,16,18,21,24,28&GR=DERS&TF=90&UF=2130&SL=2.5

It actually looks like the single SRAM goes to a much lower gear so will be better on those hills? (Or have I got it the wrong way round?)

Bobbinogs

Yepp, the picture looks right but it is hard to read the numbers on the cranks (should be 38 on the top graph, I can see the 46/36 on the lower one). It should show that the SRAM setup is generally lower geared with a wide range. If this was for pure road I would recommend against it as the gearing is very low and the big gaps could often leave you searching for a decent cadence/gear combo but for CX...I have no idea as I don't do it

wongataa

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19707541#p19707541]lesmond[/url] wrote:

Is there an idiots guide on how to calculate the ratios?

The wheels look the same size to me on those 2 examples

The gear ratio is:
The number of teeth on the chainring / the number of teeth on the rear sprocket