Your Favourite Gear Ratio
- ColinOldnCranky
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Re: Your Favourite Gear Ratio
Postby ColinOldnCranky » Mon Mar 21, 2011 3:40 pm
thinking...thinking...thinking...
Ah yes, 1:1giving me 24 gear inches. No cogs, fixed wheel with cranks attached direct to the wheel hub.
Sounds a bit like a baby's trike actually.
- Lark2004
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Re: Your Favourite Gear Ratio
Postby Lark2004 » Tue Mar 22, 2011 7:18 pm
Soooooo.... your wheel diameter is only about 7.6 inches?ColinOldnCranky wrote:My favourite gear ratio? Hmmm, lemme think about that...
thinking...thinking...thinking...
Ah yes, 1:1giving me 24 gear inches. No cogs, fixed wheel with cranks attached direct to the wheel hub.
Sounds a bit like a baby's trike actually.
or,
your wheel diameter is 24 inches which will give you about 75.5 gear inches (give or take depending on what size your tire is....)
(edit, because you have direct drive, your gear inches is the roll out of the wheel, i.e. it's circumference...)
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Re: Your Favourite Gear Ratio
Postby MiG » Tue Mar 22, 2011 8:20 pm
+1Oxford wrote:GI doesn't incorporate Pi
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Re: Your Favourite Gear Ratio
Postby Lark2004 » Tue Mar 22, 2011 8:26 pm
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Re: Your Favourite Gear Ratio
Postby Mustang » Tue Mar 22, 2011 8:39 pm
70 years young.
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Re: Your Favourite Gear Ratio
Postby MiG » Tue Mar 22, 2011 9:18 pm
That's rollout. How else do you think people are getting GIs of around 70 with common street gearing like 48:18?Lark2004 wrote:a gear inch is how many inches forward the wheel moves for one revolution of the crank
27 * 48 / 18= 72 That's the lazy GI formula that assumes 27" diameter.
- hartleymartin
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Re: Your Favourite Gear Ratio
Postby hartleymartin » Wed Mar 23, 2011 11:14 am
At the moment I'm looking at gear ratios again... I'm building up a single-speed roadster style bicycle for my personal use at college. A simple machine with minimal maintenance. In fact I would get a coaster-hub, but I already have a set of wheels which are ready for a screw-on freewheel. I'll be using north-road handlebars, steel frame, steel stem & bar, steel seat-post, steel mudguards... (lots of lovely steel)
Anyway, it's going to have 700 x 38c wheels and tyres, and a 44/18 chainring/freewheel, which gives a gear of approximately 66.8 gear inches. If I get a smaller 42-tooth chainring it'll be 63.7 gear inches. What do you think?
http://raleightwenty.webs.com - the top web resource for the Raleigh Twenty
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Re: Your Favourite Gear Ratio
Postby MiG » Wed Mar 23, 2011 11:44 am
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Re: Your Favourite Gear Ratio
Postby hartleymartin » Wed Mar 23, 2011 6:59 pm
P.S. Remember that just about everything on this bicycle will be gaspipe steel, except for the alloy rims.
On a lovely, big 62cm x 56cm (st x tt) frame:
http://raleightwenty.webs.com - the top web resource for the Raleigh Twenty
- nickobec
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Re: Your Favourite Gear Ratio
Postby nickobec » Wed Mar 23, 2011 7:50 pm
Depends on the terrain you ride and how strong your legs are. I ride a all steel except alloy guards roadster to the train station regularly. 400m (AT) 4% on brick paving or 300m (AT) 5% are the finish sections depending on direction and I am happy with 42/16 71GI on that.hartleymartin wrote: At the moment I'm looking at gear ratios again... I'm building up a single-speed roadster style bicycle for my personal use at college. A simple machine with minimal maintenance. In fact I would get a coaster-hub, but I already have a set of wheels which are ready for a screw-on freewheel. I'll be using north-road handlebars, steel frame, steel stem & bar, steel seat-post, steel mudguards... (lots of lovely steel)
Anyway, it's going to have 700 x 38c wheels and tyres, and a 44/18 chainring/freewheel, which gives a gear of approximately 66.8 gear inches. If I get a smaller 42-tooth chainring it'll be 63.7 gear inches. What do you think?
On the other hand on Sunday did a 60km belt up the freeway with a few thousand other people, this time with CrMoframe and alloy components. I needed the 52/16 85GI to be able to ride at pace aka almost 40kmh. Even managed the solo return trip into 20kmh gusting to 30kmh headwinds with out problems. The 8% grades early on the return trip where a different matter.
- hartleymartin
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Re: Your Favourite Gear Ratio
Postby hartleymartin » Wed Mar 23, 2011 9:35 pm
http://raleightwenty.webs.com - the top web resource for the Raleigh Twenty
- ColinOldnCranky
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Re: Your Favourite Gear Ratio
Postby ColinOldnCranky » Wed Mar 23, 2011 11:20 pm
Your explanation of what a gear inch and it's heritage is, afaik, pretty well perfect. It's all about the rider's inside leg measurement.hartleymartin wrote: Back in the day, 60 Inches was pretty much the standard bicycle "gear", as it was approaching the limits of what a man's leg length could accomodate.
However 60" is little on the long side unless going to exotic variants. Even with the excessively tall youths of today it would be impossible for all except maybe Manute Bole. They tend to be around 50 ,maybe, 52". Though I have seen a pic of bloke with an excessive wheel size and blocks ridiculously attached to the top of the pedals. And there is also the far more practical variation where the pedals are a fair way above the axis and linked to the axis through a pair of rods. With those the rider can go to whatever GI he wants regardless o f his inside leg measurement.
btw newly built retro penny farthings built to the old spec will become harder to come by. The solid rubber that they clad the wheel with, termed pram chord (remember the old sprung base prams of yesteryear with 1" solid rubber cladding?) is no longer manufactured I believe.
- aeroslave
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Re: Your Favourite Gear Ratio
Postby aeroslave » Wed Mar 30, 2011 11:42 pm
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Re: Your Favourite Gear Ratio
Postby hartleymartin » Fri Apr 01, 2011 1:37 pm
I'm more of a softie... at the moment It looks like I'll be trying out 42/18 single-speed.aeroslavebigbelly wrote:i'm a softie - 16x46
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- ghettro
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Re: Your Favourite Gear Ratio
Postby ghettro » Fri Apr 22, 2011 9:22 pm
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Re: Your Favourite Gear Ratio
Postby scrubnbash » Tue May 17, 2011 7:29 pm
Climbs are better when they're over faster.
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Re: Your Favourite Gear Ratio
Postby ldrcycles » Tue Jun 14, 2011 6:46 pm
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Re: Your Favourite Gear Ratio
Postby rkelsen » Tue Jun 14, 2011 7:57 pm
Far out man! You make it sound like maintaining 100rpm is easy!nickobec wrote:I needed the 52/16 85GI to be able to ride at pace aka almost 40kmh.
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Re: Your Favourite Gear Ratio
Postby nickobec » Thu Jun 16, 2011 6:07 pm
It was that day with a 20kmh tailwind & a bunch of 50 people, until I moved out of the inside of the bunch because they where all moving around, worrying me and outside into the wind.rkelsen wrote:Far out man! You make it sound like maintaining 100rpm is easy!
Last Sunday slogged 30km into a 30kmh gusting to 40kmh headwind, wanted a 52x19 or 20. it was all 60rpm. Then I got to ride home with tailwind and close to 100rpm.
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Re: Your Favourite Gear Ratio
Postby grinderman » Sat Aug 20, 2011 1:22 am
This means I grind up the hills, there are places on the 1 in 20 where I am doing less than 15 cadence. The computer goes to zero under 15. It does mean I can fly down though, I can pedal through to over 70 kmh,up over 160 cadence cooming down. On the flat I can hold 48 with 53 flat out.
This is my daily commuter, 48 km round trip, eastern burbs to hawthorn.
This isn't for everyone and has taken a while to work up to. I started with a 48x 18 and worked my way up. Changing the cog then the ring to 52x16 then 54, 58 and now 60. I did have 60x16 but this is too hard in the hills.
I have hand cut and filed bigger rings than this for my recumbent and for a raleigh twenty. For the record my knees are still ok.
Happy grinding!
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Re: Your Favourite Gear Ratio
Postby BRLVR.v2 » Sat Aug 20, 2011 7:46 pm
you are until we see a picgrinderman wrote:This is going to sound pretentious and I wasn't going to post because I will sound like I'm just making stuff up, !
- verbs and nouns
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Re: Your Favourite Gear Ratio
Postby verbs and nouns » Sun Aug 21, 2011 7:38 pm
48 x 17 on the other two.
All brakeless.
Andy MASH SF wrote:You ride a (brakeless) track bike on the city street because it’s stupid and reckless–and by default: bad-ass.
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Re: Your Favourite Gear Ratio
Postby BRLVR.v2 » Sun Aug 21, 2011 8:29 pm
17 skid patches FTWverbs and nouns wrote:49 x 17 on one track bike.
48 x 17 on the other two.
All brakeless.
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Re: Your Favourite Gear Ratio
Postby grinderman » Sun Aug 21, 2011 11:06 pm
well that didnt seem to work,
here are links instead,'
Repco Revenge 60 x 17
https://picasaweb.google.com/lh/photo/p ... directlink
https://picasaweb.google.com/lh/photo/X ... directlink
the Repco is the training bike for my unofficial world record attempt on
the Worlds fastest Raleigh Twenty 80 x 20
https://picasaweb.google.com/lh/photo/i ... directlink
https://picasaweb.google.com/lh/photo/o ... directlink
https://picasaweb.google.com/lh/photo/c ... directlink
Martin, who kicked off this thread may recognise this as my blue bike repainted from jhnboy on the R20 forum
Ride 1 in 20
http://theclimbingcyclist.com/climbs/mt ... e-1-in-20/
Knee
https://picasaweb.google.com/lh/photo/y ... directlink
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Re: Your Favourite Gear Ratio
Postby b7ff » Thu Sep 08, 2011 9:18 am
but now Im on 49 x 18; its not that bad really, it is fast thoughh
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