I don't get no respect, an R20 appreciation thread.
03-02-08, 05:41 PM
#26
The Legitimiser
Join Date: Jul 2005
Location: Southampton, UK
Posts: 4,849
Bikes: Gazelle Trim Trophy, EG Bates Track Bike, HR Bates Cantiflex bike, Nigel Dean fixed gear conversion, Raleigh Royal, Falcon Westminster.
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What size cog did you put on it?And maybe,if you don't mind,could you explain"gear inches"to me.?I've heard the term but never get it much thought.I've usually just made do with the gearing the bike came with.I usually don't modify my bikes,I like them original.But I've been thinking on changing the cog because 3rd IS pretty useless unless your really flying along(on flat ground
).
).https://www.sheldonbrown.com/gloss_g.html#gearinch
But basically, it's derived from what the equivalent circumference wheel would be on a penny-farthing! It tells you how far the bike will travel per turn of the cranks, pretty much. Fixed gear and single speed guys like to be around 70 gear inches, which is high enough to get along pretty fast, but low enough that they can get away from the lights and still climb hills. This stuff becomes pretty important when you only have one gear! Basically, that's halfway between 2nd and 3rd on a standard R20, which is about where I wanted to be a lot of the time. As you've discovered, 80 is quite high even on flat ground (certainly with those god-awful granny tyres), but not really enough on descents. I'm now thinking that with a 52 tooth chainwheel, and a 16t cog, I'll have a nice set of ratios. 1st will be lower than my old first, second will be roughly what my old 1st was (which was always good enough, frankly), 3rd just a little higher, 4th exactly where the old second was, 5th is 69 inches, which is about what I really want for flat/rolling riding, 6th is more or less where the old 3rd was, and 7th gives me that bit extra for really bombing descents, and keeping the momentum up on the flat afterwards.
I think that'll work well for me, though it actually doesn't play that well to where the small gaps are on a Nexus 7. It'll also give me an issue with chainguards - the standard one won't go over a 52t chainring, and I don't think Hebie Chaingliders will either. Hmmmm.
I should have known that Sheldon's site would have the answer.
