i've been messing around with gear ratio's for the past couple of days. recently i've run 44x18 but felt i could increase the gear inches.
i tried 48x18 today, which has helped reduce my cadence (i find i start bobbing on the saddle at 120+) but obviously hurt my climbing. my top speed was higher, but my average speed was slightly lower.
my question is, the 44T ring was on a 172.5mm crank while the 48T was on a 165mm crank (different bcd cranks and rings lying around...) will going for a 48T ring on the 172.5mm crank make much of a difference, or should i go mid way for a 46T ring...?
44x18
48x18
Gear ratios and crank length
- mitchy_
- Posts: 878
- Joined: Sun Jan 05, 2014 11:15 am
- Contact:
- HLC
- Posts: 722
- Joined: Sun Mar 04, 2012 11:23 pm
- Location: Sydney.
Re: Gear ratios and crank length
Postby HLC » Fri Jan 17, 2014 8:09 pm
Crank length is a matter of bike fit.
48/18 is the same regardless of crank length. (or whatever other ratio you choose)
48/18 is the same regardless of crank length. (or whatever other ratio you choose)
- mitchy_
- Posts: 878
- Joined: Sun Jan 05, 2014 11:15 am
- Contact:
Re: Gear ratios and crank length
Postby mitchy_ » Fri Jan 17, 2014 8:20 pm
yes, but you can apply more leverage/torque to a longer crank.
- toolonglegs
- Posts: 15463
- Joined: Fri Jun 29, 2007 7:49 pm
- Location: Somewhere with padded walls and really big hills!
Re: Gear ratios and crank length
Postby toolonglegs » Fri Jan 17, 2014 8:24 pm
48/18 is 48/18 no matter what the crank length is... but to maintain the same cadence your legs will have to travel further ( make bigger circles ) with the longer crank length.HLC wrote:Crank length is a matter of bike fit.
48/18 is the same regardless of crank length. (or whatever other ratio you choose)
-
- Posts: 10316
- Joined: Thu Sep 18, 2008 12:10 pm
- Location: Sydney
Re: Gear ratios and crank length
Postby Nobody » Fri Jan 17, 2014 10:50 pm
I don't know if this is what you're looking for, but longer cranks reduce the effective gearing while shorter cranks increase effective gearing. So a 165mm cranks has an effective increase in gearing over 172.5mm cranks of 172.5/165 = 1.045 or 4.5%.
-
- Posts: 3493
- Joined: Thu Jan 10, 2008 1:39 pm
Re: Gear ratios and crank length
Postby rustychisel » Wed Jan 22, 2014 10:29 am
Yes, theere's a force multiplier, but you're overthinking it given the variable of leg speed (cadence).Nobody wrote:I don't know if this is what you're looking for, but longer cranks reduce the effective gearing while shorter cranks increase effective gearing. So a 165mm cranks has an effective increase in gearing over 172.5mm cranks of 172.5/165 = 1.045 or 4.5%.
-
- Posts: 10316
- Joined: Thu Sep 18, 2008 12:10 pm
- Location: Sydney
Re: Gear ratios and crank length
Postby Nobody » Wed Jan 22, 2014 10:44 am
Depends if you have a variable leg speed preference. Most people don't appear to. So if a preferred leg speed is fixed, then cadence increases as an inverse of crank length. So for the same bike speed, the average person's preference will be to change down a gear to keep their preferred leg speed or (now higher) cadence with shorter cranks. If that is the case then the shorter cranks have effectively increased the gearing. I have found this in my case.rustychisel wrote:Yes, there's a force multiplier, but you're overthinking it given the variable of leg speed (cadence).
Last edited by Nobody on Wed Jan 22, 2014 10:46 am, edited 1 time in total.
-
- Posts: 3493
- Joined: Thu Jan 10, 2008 1:39 pm
Re: Gear ratios and crank length
Postby rustychisel » Wed Jan 22, 2014 10:46 am
Sure, but if you can't maintain and adjust cadence then you can't ride fixed gear. Eh?
-
- Posts: 10316
- Joined: Thu Sep 18, 2008 12:10 pm
- Location: Sydney
Re: Gear ratios and crank length
Postby Nobody » Wed Jan 22, 2014 10:49 am
But why would I want to ride fixed?
- HappyHumber
- Posts: 5072
- Joined: Wed Nov 14, 2007 11:48 pm
- Location: Perth, (S.o.R.) W.A.
Re: Gear ratios and crank length
Postby HappyHumber » Wed Jan 22, 2014 12:28 pm
Keep a 17t on the back for max skid joy.
--
Hit me up via the BNA dm; I'll get an alert. If y'know, you know.
Hit me up via the BNA dm; I'll get an alert. If y'know, you know.
- singlespeedscott
- Posts: 5510
- Joined: Sun Jan 20, 2008 4:35 pm
- Location: Elimbah, Queensland
Re: Gear ratios and crank length
Postby singlespeedscott » Thu Feb 20, 2014 1:00 am
I have found over the years that my gearing has slowly reduced, yet my average speeds have remained the same. Currently my prefered ratio is 44x17.
As for crank length. I prefer 165's as they are easier to spin at high RPM's and they allow you to go deeper into the corner with less worry about pedal strike. They feel strange initially after using the 175's on my geared bikes but I get use to it within a few km's.
As for crank length. I prefer 165's as they are easier to spin at high RPM's and they allow you to go deeper into the corner with less worry about pedal strike. They feel strange initially after using the 175's on my geared bikes but I get use to it within a few km's.
Return to “Fixed Gear/ Single Speed”
Jump to
- General Australian Cycling Topics
- Info / announcements
- Buying a bike / parts
- General Cycling Discussion
- The Bike Shed
- Cycling Health
- Cycling Safety and Advocacy
- Women's Cycling
- Bike & Gear Reviews
- Cycling Trade
- Stolen Bikes
- Bicycle FAQs
- Serious Biking
- Audax / Randonneuring
- Retro biking
- Commuting
- MTB
- Recumbents
- Fixed Gear/ Single Speed
- Track
- Electric Bicycles
- Cyclocross and Gravel Grinding
- Dragsters / Lowriders / Cruisers
- Children's Bikes
- Cargo Bikes and Utility Cycling
- Road Racing
- Road Biking
- Training
- Time Trial
- Triathlon
- International and National Tours and Events
- Cycle Touring
- Touring Australia
- Touring Overseas
- Touring Bikes and Equipment
- Australia
- Western Australia
- New South Wales
- Queensland
- South Australia
- Victoria
- ACT
- Tasmania
- Northern Territory
- Country & Regional
- The Market Place
- Member to Member Bike and Gear Sales
- Want to Buy, Group Buy, Swap
- My Bikes or Gear Elsewhere
- Cycling Brands
- Cannondale
- Garmin
- Giant
- Shimano
- Trek
Who is online
Users browsing this forum: No registered users
- All times are UTC+11:00
- Top
- Delete cookies
About the Australian Cycling Forums
The Australian Cycling Forums is a welcoming community where you can ask questions and talk about the type of bikes and cycling topics you like.
Bicycles Network Australia
Forum Information
Connect with BNA
Brought to you by Bicycles Network Australia | © 1999 - 2024 | Powered by phpBB ®
This website uses affiliate links to retail platforms including ebay, amazon, proviz and ribble.
This website uses affiliate links to retail platforms including ebay, amazon, proviz and ribble.