..
 

..

The compact (assuming 50/34T chainrings) with a 27T cog gives a 34 gear-inch low gear. A 34T cog with your current 39T chainring gives a 31 gear-inch low gear. Based on what I've read about the Mt. Washington hill climb neither is low enough unless you are a Cat 1 or better rider.

Others who have ridden the climb say a 27 gear-inch low is an absolute highest low gear they would consider and lower, a lot lower, is better. I've heard of MTB cranks (42/32/22T chainrings) and a Xx32 or 34T cassette being used and they used the lowest gear they had. It's not just the incline, the wind can be ferocious too and that makes the hill far worse.

I see you are from my area. What gearing would you want to use to ride Sycamore St, Realto St. or Potomic Ave. into a stiff headwind if they were over seven miles long?

dang it, was adding something to my post and it went all haywire, now its gone... anyhoo, thanks for the advice, I have just started getting things in line on the bike for the ride so I will investigate further into what the more common setups are for the climb. Thanks Hillrider :)

Wow! I've heard about this climb for years, but I guess I never realized just how tough it is. I've ridden a lot of fairly long, steep, paved hills with mountain bike cranks (NOTHING like Mt. Washington, obviously), and I'm a spinner not a masher, but I'm having a hard time imagining a paved hill that would require 22/34 unless you were doing heavily loaded touring. Thanks for posting that-

I have a 24/34 low gear on my recumbent, and I used it for a (thankfully short) climb away from a river ferry while loaded touring. It was barely faster than walking.

This doesn't go very high, but this Portland ride would be good training for Mt. Washington:
http://www.opb.org/programs/ofg/segments/view/1728

I can definitely see the need for gears like that with loaded touring. I've had a couple of touring bikes with those gears myself, in fact. But what Hillrider is saying is that there are people who have come just to climb this thing and some of them are needing the absolute granny gear with a mountain bike drivetrain just to deal with the length, the grade, and the wind. That's BRUTAL!

you mentioned in your original post (gone) that you were concerned about the posibility of balky shifting on the rear. assuming a ten speed casette, I wouldn't imagine the tooth difference between chainrings would be anything a good long cage rear derailleur would not be able to handle with ease. Remember, back in the days when you could only get 5 or 6 cogs on the back, people used to deal with ungodly tooth gaps between the largest cog or two and the rest if they wanted to climb really steep hills (and then pedal down them).

As far as the gear ratios not being as closely/nicely spaced, remember: you are climbing a mountain. Better to have a wider difference between ratios for the wider difference between grades that you are likeley to encounter.(I am not familiar with this climb.)

Thanks Kludge... My original post got all snafu... not sure where it went lol...... I was really hoping to retain my short cage der by using a 12-27 in the rear, which seems possible by going with a 22t crankset (MTB), giving about a 21inch low gear. I like the idea of a closer spaced rear cassette so there is less of a jump between ratios making it a bit easier to maintain a good cadence. This is just an uphill, no downhill permitted (must have ride back down.).