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absolute beginner View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote absolute beginner Quote  Post ReplyReply Direct Link To This Post Posted: 24 February 2012 at 8:05pm
Hi All!
 
Hi tongskie01, just done bit of maths. Hope this is of interest.
 
(175mm crank) centre line of pedal spindle travels a distance of 1099.6mm per 1 revolution.
(155mm crank) centre line of pedal spindle travels a distance of 973.9mm per 1 revolution.
 
By making the swap you cut the distance travelled by pedal spindle by 11.4% a good reduction per stroke at any rpm.
 
Any idea how much you geared down to compensate? 
 
Here are a couple more.
170mm to 110mm decrease distance travelled by pedal spindle 35.3% per revolution.
155mm to 110mm decrease distance travelled by pedal spindle 27.6% per revolution.
 
All the best!
 
too fat for too long, time to get fit again!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote absolute beginner Quote  Post ReplyReply Direct Link To This Post Posted: 24 February 2012 at 9:26pm
Hi All!
 
Amendment to last post.
 
152mm to 110mm decrease equals 27.6%
 
155mm to 110mm decrease equals 29.0%
 
All the best!
too fat for too long, time to get fit again!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote johnlucian Quote  Post ReplyReply Direct Link To This Post Posted: 24 February 2012 at 10:04pm

Just for laugh, "but true"! In 2010 my first year of championship, starting very very slowly. I had 175mm aluminium cranks and decided to modify my cranks, I make new spindle tap holes at 150mm just the Saturday before second Hillingdon race. I was not sure how I will fill moving directly from 175mm cranks to 150mm, so I did not cut off the ends of cranks. At the end of race I spotted that my right pedal was mounted on 150mm crank length and the left pedal was at 175mm (I have a witness on this). I did not feel anything different during the race, and my results was better than before (not because of this, but because of more training during season). I am confident that having the left/right pedals at different it did not affect my race!

A clear change after I moved to 150mm cranks is that I did not strain my knees anymore doing the same speed on the same hills; obviously to get the same speeds I was pedalling faster.

John Lucian
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tongskie01 Quote  Post ReplyReply Direct Link To This Post Posted: 25 February 2012 at 1:35pm
i have calculated my lowest gear inches before i bought a smaller chainring. before it was 28.42 gear inches  after it is 23.87. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote absolute beginner Quote  Post ReplyReply Direct Link To This Post Posted: 25 February 2012 at 7:09pm
Hi All
 
Hi tongskie01
Gearing 28.42in down to 23.87in=16% (Reduction).
Crank 175mm down to 155mm =11.4% (Reduction).
 
Is any body finding similar figures? There could be formula forming.
 
All the best!
 
 
too fat for too long, time to get fit again!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave Tigwell Quote  Post ReplyReply Direct Link To This Post Posted: 25 February 2012 at 7:36pm
Hello again, it`s all very interesting but my concern is this-I have been running 145mm cranks since 2007 on both Cuckoos and although I found a difference at first, and pedaled at a cadence in upper 90s I soon got used to it. As my fitness increased , more recently I have noticed my average cadence come down to low 80s so I`m using higher gears and my legs hurt more after a hard ride.They also take longer to recover. I`ve only just made this connection on account of not being very quick off the mark. Tomorrow I will do 40-50 miles and try to keep a high cadence. It will be interesting to compare my performance with others in the group (all riding safety bicycles) as we ride together twice a week and know each other`s abilities, and my recovery time afterwards. Of course it might be something to do with not having had a Cornish pasty this year. Now I have recumbent legs I don`t have upright legs any more.
dave T
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Post Options Post Options   Thanks (0) Thanks(0)   Quote absolute beginner Quote  Post ReplyReply Direct Link To This Post Posted: 26 February 2012 at 2:49pm
Hi All!
 
Maybe variety is the spice of life. Riding with various crank sizes may be the only way keep the flexibilty up.  One thought I had was to ride my upright on 170mm , build my road-going LB with 152mm and build my racer with 110mm.
Training a few days prior to racing on the short cranks just to improve proficiency of movement. Take advantage of the fresh feeling, higher cadence, ease on the knees and return straight back to the longer cranks for my normal joureys.
 
All the Best!
too fat for too long, time to get fit again!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tongskie01 Quote  Post ReplyReply Direct Link To This Post Posted: 26 February 2012 at 8:34pm

i found out that when i was starting to ride a recumbent, it takes some time to develop my leg muscles.  but when i came back to ride my upright with my friends , it doesnt feel like i struggle at all. is it because of spinning effeciency?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote cranked forward jim Quote  Post ReplyReply Direct Link To This Post Posted: 27 November 2012 at 10:57pm
My home made semi recumbent has a short crank because I found I had a lack of ground clearance without it. Recently I bought a LWB recumbent which has a 'normal' 170mm crank. I immediately wanted to swap them over as I felt like my legs were flailing around in the air!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bazz Quote  Post ReplyReply Direct Link To This Post Posted: 28 November 2012 at 8:32pm
Once you have experienced the dark side, it's difficult to go back! ;-)

I am experiencing the same horribleness having borrowed an upwrong to commute to work on for now. can't wait till I find a new LB commuter and fit some shorties to it.
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