Tninking of a new bike, Crank and cassette question

[Andrew_P]

Okay I have a Marin 29er. Fairly slim wheels not mega heavy use it to commute a return journey of 30 miles.

I think I would find a road bike more comfortable and quicker. My small concern is gearing the Marin is a triple TruVativ X-Flow C 3.0, 48/38/28 Shimano HG30, 11-32, 8 Speed.

The road bikes I am looking at are Cassette : Shimano 105, 10-speed, 12-27t Chain : KMC X10 CP Crank Set : Shimano FCR-550 Chainwheels : 53 x 39T



The main concern is that one of the hills on the commute I use 2nd gear and the middle 38 on the front. How much different would the new spec be? Or in other words witll the new bike still have that gear!!

 

[RecordAceFromNew]

Second gear on the middle chain ring of your current bike is I believe 38x28 (for an HG30 that is 11/13/15/18/21/24/28/32). The lowest you can go on the future bike is 39x27.

All else (tyres, crank length) being equal the lowest gear of the new road bike is going to be 6.4% higher than the current bike's 2nd gear on the middle ring, so in simple terms the answer is no.

However if the road bike is lighter, its tyres are slicker, skinnier and pumped up at higher pressure than what you have now, then you might find it ok for the same hill. More info on current and future bikes' spec, especially tyres, might help.

If you are buying the road bike new, the shop might well be willing to swap the cassette for a wider range one for free. A largest sprocket of 29T (as opposed to 27T) will do.

If you want to play around with gear combinations, this works.

 

[Andrew_P]

Great info thanks.
I think I could live with the 6.4% as I do not always go up to 2nd, and if it wasn't there I would probably get used to it, and if not as you say change the cassette at worst. It was the front I wanted to up to 53 I do not think I would see much of a differnce from 48 to 50 and most of the tourers seem to have 50


http://www.evanscycl...ampaign=froogle

This is the bike I have been considering, or similar

Current http://www.marinbikes.com/2008/us/bikes/specs_muirwoods_29er.php

Thinking about it probably more often use 1st or second and on the top ring at the front so 48 x 32

 

[RecordAceFromNew]

Taking account of the different tyre size, the difference is more like 1%. Since the road bike is going to be much (I guess ~4kgs) lighter, chance is you will be flying up that hill!

 

[surfdude]

just brought a road bike after years on a mtb and its only a double . its great there is a hill i ve never got up on my mtb which has 27 gears first time on my new 18 speed road bike i made it to the top , all right i could not feel my legs because of the pain and breathing was nearly impossible but who cares i made it to the top in one go so dont worry when you get one you will think why did i not get one of these road bikes sooner