Anyone any good at working out gear ratios?

[Old man Jimbo]

Long story short.

I'm a fatman who bought a second hand MTB over a few months of faffing about to get a half comfertable ride and some degree of fitness. I was toying with buying this... http://www.edinburghbicycle.com/ebwPNLqrymode.a4p?...

But me and some other members of "team midlife crisis" go on monthly rides out for a bit of publunch and a giggle which needless to say has decended into some pretty harsh rides. The last one has really made me question buying the above bike, basically on the last ride out I had the front on a 24 chain ring and on the rear 32 ring with 26"x1.5" tyre I made it round the 32miles of hell.

So I was thinking perhaps this bike may have a better set up for the really nasty hills... http://www.edinburghbicycle.com/ebwPNLqrymode.a4p?...

I don't know how good the lowest gears would be? Any help on how to work it out would be great. My MTB has 26" wheels but what size is 700x25c compared to 26"x1.5"? Sorry if these are "idiot" questions... But hey if I'm splashing out on a new bike it would be nice to know I've an outside chance of getting my lard ass up some of Dumbria's highest hills..

[paranoid airbag]

if it helps, my trip computer's manual has a rough list of rolling circumferences, 26x1.5 is 2010mm and 700x25c 2105, so you'd want slightly lower gears on the 700c tyre - but that difference will likely be overwhelmed by the weight and rolling resistance change going from mtb to roadie (I've recently made the jump - SO much better, but I've got no hills nearby)

[b2hbm]

Generally speaking, MTB's have significantly lower gear ratios than road bikes like the 2 you have listed.

A 24 x 32 with a 26" wheel is a very low ratio, and nothing on those two bikes will come close to it. Of the 2 bikes, the Rev. Conti. Pro has a looks to have a lowest gear of 34x23, which, for a road bike is low but still well above what you've been using. The bike is no doubt lighter and there will be less drag from the thinner wheels, but I doubt it would make up the difference.

The 2nd one, the Specialized, has a lower bottom gear at 34x32, which is very low for a road bike but still well above what you're using. Going into geek mode, the 34x32 works out at something like 28 inches but your 24x32 on a 26" wheel is around 19 inches (forget the "inches", just work on the relative numbers )

If you're set on a road bike then the Specialized is the closest of the 2, and I think as your fitness improves you'd be ok with that sort of gearing. But the only way to get a set of gears approaching your MTB is either to buy a road bike meant for touring with a triple set up and large rear sprockets (they are typically 52/39/30 with rear sprockets up to 32), or use MTB transmission on a custom build.

[b2hbm]

Forgot to add;

Gears are measured in "inches" which means the effective diameter of the wheel and goes back to the days of the old penny-farthing type of bike. Ignore all that and just use the numbers as an idea of the ratio.

this page has a good gear calculator where you can try different combinations.

http://www.sheldonbrown.com/gears/

As a guideline for low gearing, road bikes usually have bottom gears between 40" & 50", touring bikes 30", and 20" is reserved for climbing walls....

[TheInternet]

Sheldon Brown's Bicycle Gear Calculator
ETA: Beaten to it.

Edited by TheInternet on Saturday 19th March 17:20

[Old man Jimbo]

Many thanks for the informative replies. I'm leaning towards buying the specialized at the mo. I'll keep the old freak machine and use that for wet and winter trips to work and back and dig it out when the rides get silly steep..

Cheers again!