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Short Cranks

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URL: http://forum.bhpc.org.uk/forum_posts.asp?TID=4484
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Topic: Short Cranks
Posted By: AlanGoodman
Subject: Short Cranks
Date Posted: 24 January 2012 at 12:05pm
There is now an article on short cranks by Mike Burrows in the http://www.bhpc.org.uk/magazine-extra.aspx" rel="nofollow - Magazine Extra section of the web site...

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Replies:
Posted By: Bill B-J
Date Posted: 29 January 2012 at 2:38pm
As Mike says, bodies  are complex.

In case it is a useful consideration, some generalisations:-

Muscle produces most power in mid range. (Inner range being close to as short as it gets, outer being, close to as long as it gets.)

Maxiamal compression between knee cap, (patella,) and thigh bone, ,(femural condyles,) mechanically will occur when the quads are contracting through 90 degrees of knee bend (flexion.) Which is why patello-femoral problems manifest, walking/running up and down hills/stairs; grinding on the pedals with longer cranks, and presumably why shorter cranks help those with such a problem.

If there is a theoretical down side to shorter cranks; perhaps one draws on a larger collection of muscle fibers , when contracting through the full range of a muscle, and fewer when the using a shorter range. Superior blood supply to great number of fibers, perhaps.

It would be a surprise, if like many other things in life, there was not a balance to be found!



Posted By: Bill B-J
Date Posted: 01 February 2012 at 6:13pm
Questions-

Does one reduce the gearing, in relative to the percentage shortening of the crank?

And, off the shelf shorter cranks seem to be rare. I understand hollow cranks are no good for cutting down. Are there favourite cranks for shortening?


Posted By: graydog
Date Posted: 01 February 2012 at 6:36pm
I personally find old school cranks have more meat on (so to speak) for allowing shortening.
There are ways to do hollow cranks, by moulding in inserts.

For standard cranks I generally seek blackwidows, BMX. I think they go down to 140mm but on 110mm BCD spiders. So you may need to make carries for your 130 shams, or 135 cantis.

Not sure the are generally available new either, as heard a rumor the where not being sold anymore. But i have seen them for sale since.

Cost around 60quid.


Posted By: Wyndrake
Date Posted: 02 February 2012 at 9:37am
Billie-J - Have a look at www.unicycle.com based in Stockton. They stock a wide variety of crank lengths starting at 90mm, priced at around £30.

Regards,

Alan


Posted By: Wyndrake
Date Posted: 02 February 2012 at 9:42am
Bill B-J - Apologies for mis-naming you.Embarrassed


Posted By: Paul Lowing
Date Posted: 02 February 2012 at 1:10pm
But surely unicycle cranks don't have any means of attaching a chainring...


Posted By: graydog
Date Posted: 02 February 2012 at 1:19pm
Some unicycles use chains or very very long legs ;)


Posted By: Wyndrake
Date Posted: 02 February 2012 at 10:52pm
Unicycles stock a variety of splined ISIS and system cranks such as Schlumpf (which I use on velomobile and used on the Windcheetah Hypersport.

Middleburn also supply interchangeable splined cranks compatible with Shimano XTR rings. However, I believe they only go down to 160mm as a stock item.

Regards,

Alan


Posted By: Adrian Setter
Date Posted: 03 February 2012 at 12:31pm
Originally posted by Bill B-J Bill B-J wrote:

Does one reduce the gearing, in relative to the percentage shortening of the crank?
 
You certainly should expect to need to reduce your gearing.  Simplistic mechanical thinking would indeed suggest that it should be by the same proportion as the reduction in length of the crank, so keeping the overall gearing (in terms of distance moved by the pedal to distance moved on the road) the same.
 
This is pretty much what I've done to my road recumbent, going from 170mm to 145mm cranks and from a 50T chainring to a 42T.  My limited experience so far is that I'm spinning out at a speed about 10% lower than I did do, so either I shouldn't have gone for quite such a small chainring, or I just haven't learned to spin those short cranks properly yet.


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Challenge Hurricane - MicWic Delta (Front half) - Burrows Ratracer


Posted By: GeoffBird
Date Posted: 03 February 2012 at 9:18pm
I've been using 150's for some time - I think I agree with Adrian that a mathematically proportionate reduction in gearing (what I have) is probably overdoing it very slightly, but it feels okay.

I was lead to believe that BMX cranks used a different pedal thread?


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Right Time - Right Place - Wrong Speed


Posted By: graydog
Date Posted: 03 February 2012 at 9:59pm
The blackwidow BMX fit standard square tapers BB


Posted By: GeoffBird
Date Posted: 04 February 2012 at 1:36pm
But, do they take standard pedals Graham? I believe some do not.

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Right Time - Right Place - Wrong Speed


Posted By: graydog
Date Posted: 04 February 2012 at 2:19pm
I can not say in generally, but i can say the Blackwidows i use do have standard pedal threads.
I've been using them for about 4yr and swap the pedals between bikes.

Hope you well regards Gd


Posted By: SteveArmstrong
Date Posted: 04 February 2012 at 4:35pm
I just found some 150mm 2 rings cranks on ebay (38T, 48T). I was tempted but they say 1.1Kg which seems a lot, probably cast iron  Tongue. I just weighed my 2 ring 175mm crank set at 724g. I might not notice the weight difference though.

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When you pull the cats tail, you get the whole cat.


Posted By: tosgh
Date Posted: 12 February 2012 at 1:25pm
SPA CYCLES XD-2 Touring Triple Chainset £35.00

and in 160mm lengths too! Could be a bargain!



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weight is everything


Posted By: GeoffBird
Date Posted: 12 February 2012 at 1:33pm
I phoned Spa Cycles because they were advertising 150mm cranks at one time - turned out to be a typo. You got a link Glyn?

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Right Time - Right Place - Wrong Speed


Posted By: SteveArmstrong
Date Posted: 12 February 2012 at 6:32pm
OK, I've just taken the plunge and ordered a 127mm crank, hope I like it.

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When you pull the cats tail, you get the whole cat.


Posted By: tosgh
Date Posted: 12 February 2012 at 7:55pm
http://www.spacycles.co.uk/products.php?plid=m2b0s109p2000" rel="nofollow - http://www.spacycles.co.uk/products.php?plid=m2b0s109p2000

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weight is everything


Posted By: GeoffBird
Date Posted: 12 February 2012 at 8:47pm
Thanks Glyn.

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Right Time - Right Place - Wrong Speed


Posted By: absolute beginner
Date Posted: 16 February 2012 at 9:01pm
Interesting subject. I think of a body builder I know whose training regime involved bench pressing 150 kg for three sets of 10 repetitions. As he would put it with "good form" performing a deep full range movement. At this point he would fail to complete the final repetition. After a short break add 20kg and perform "half form" presses for three more sets to failure. He explained that he could lift more over the last four/ five inches of the exercise.
I asked if he thought the same would apply to a shorter crank set up on a bike. The foot position at bottom of the pedal stroke would be the same regardless of crank length. Due to the shorter uplift he reasoned that you should be able to produce as much (or more power), perform the motion more quickly, with less fatigue. One thing he did note was that reducing the overall crank stroke by 40mm (170mm down to 150mm) may be less noticable than reducing eighteen inches of arm travel in a bench press to the last four inches of the push.
 
Best wishes to all!


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too fat for too long, time to get fit again!


Posted By: GeoffBird
Date Posted: 16 February 2012 at 10:05pm
Interesting 'cross-cultural' analysis Andrew. I've wondered whether the range of leg movement used in running would be most efficient for fast, repetitive work, as this is what human legs evolved for?

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Right Time - Right Place - Wrong Speed


Posted By: absolute beginner
Date Posted: 18 February 2012 at 1:32am
Hi All. Sorry this turned into an essay.
 
Good point Geoff. You may have helped identify the answer to the short crank question. The action required by a bi-ped to make forward motion is to lose balance, regain it momentarily and repeat. What ever the discipline, walking, jogging or running, we are preventing ourselves from falling. If we are running we are aiming for an optimally efficient "stride length". This is something very personal and dependant on leg dimensions. For example Usain Bolt 6' 5" tall and me at 5' 9" are stood with our heels on the start line. We both walk out 10 strides and stand still. It would be fair to say I will be one or two of my strides behind Usain. I cannot increase my stride to compensate (legs not long enough)and decreasing my stride will reduce optimum efficiency. My only option is increase my leg speed. If Usain's leg speed is 1 then my leg speed needs to be 1.2 to keep up. As a runner. How do I do this? I increase my arm speed as the leg speed naturally tries to keep up. Success at beating Usain now depends on arm speed, leg speed and a miracle!
 
Only an opinion (a dangerous thing to have) the questions are far more than short crank? better? long crank? worse?
 
The brief would be for the required dimensions for a hpv, e.g. for me at 5' 9", which would give me optimum efficiency for the discipline I am undertaking? This should include investigation into an optimal crank length which will help me maintain X number of revolutions, with a given gearing, for the duration required without incuring injury. (Add aero requirements as needed).
 
The permutations equal a very large number. I would love to have the facility of time, money and technical expertise to test these variables.
  
I understand the HPV movement is already testing a variety of different crank lengths but there are still problems linked to standard size availability. I'm sure someone will create a formula which will help mathematically to find crank lengths which best suit an individual. 
 
Something to keep in mind. (I know these are powerstation cyclists)
In 1988 Francesco Moser ran a 1.03m diameter rear wheel to take hour indoor record.
In 1994 Miguel Indurain pushed 190mm cranks 100rpm on gearing 59x14. (Was this his optimum crank length for the discipline?) to take the hour record.
 
Mike Burrows may know what crank lengths Boardman and Obree used. I would be interested to know. Indurain was 6' tall I'm nor sure about the others. This may have an influence on the choice of crank size. He could have just needed extra leverage.
 
All the best.
   


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too fat for too long, time to get fit again!


Posted By: Bill B-J
Date Posted: 18 February 2012 at 9:32am
Absolute beginner--
'Only an opinion (a dangerous thing to have)'--only if one attaches to it, and are not open to reality being different from the present perception!Smile

10 repetition maximum; an often used training protocol to get an increase in power largely. Maximum being subjectively set by the last repetition being difficult to complete with control. Many variations on how to use it. Like training a particular range of movement/ range of muscle length, and many other potential variables.

Running, multi factorial, complex. Being with the feeling of how it is, could be used as an assessment tool, and a way of allowing optimal neurological performance/ neuroplasticity---( neurological change,)--a view--> the  common 'scientific' reductionist view  overlooks the global picture---by definition. It is not only muscle and joints the move us.

My newly order Quest XS comes with standard 155mm cranks Big smile



Posted By: Hedgehog
Date Posted: 18 February 2012 at 1:42pm
Short cranks are available - I have managed to find a source of cranks of 155 mm in length, which are suitable for chain wheels with a pitch circle of 130 mm by 5 holes.
Also available are : Short crank 140 mm for 2 chainerings, pitch 110 mm.


Posted By: GeoffBird
Date Posted: 18 February 2012 at 6:06pm
Hi Hedgehog, yes, 155s are fairly easy to get as I think they are used on kid's bikes. Sometimes they are reasonable quality. I bought some of these from Raptobike: http://www.raptobike.nl/components/drivetrain/cranksets/crankset-155mm.html" rel="nofollow - http://www.raptobike.nl/components/drivetrain/cranksets/crankset-155mm.html   They are currenntly Euro 50.

As Andrew says, the physiological effects have to be offset against the aero effects. On an unfaired bike the 'pedalling envelope' is smaller with short cranks, but the foot-speed higher. Who knows which is better for aero, on arecumbent or an upright? In a faired bike the fairing can be made smaller with short cranks.

The Kingsbury K-Drive eliptical-path pedal system very effectively reduced fairing size in the 1980s, but (without wanting to put words in his mouth), I think even Miles Kingsbury would concede now that 120mm cranks may well achieve the same thing, with greater mechanical/pysiological efficiency. Delft Team take note! Smile



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Right Time - Right Place - Wrong Speed


Posted By: NickM
Date Posted: 20 February 2012 at 9:37am
Legs not being weightless, there is a significant oxygen cost associated with rotating them, even against zero load. This component of total oxygen cost is increased with the higher cadences typical of short crank use.

I would argue that leg strength is of little relevance to cycling performance, the overwhelmingly more important factor being blood supply to the working muscle.

The optimal crank length for an individual, nevertheless, may be influenced by the "recycling time" of muscle fibres. Short cranks may facilitate cadences which are optimal for people with predominantly fast-twitch fibres; people with predominantly slow-twitch fibres may be better served by longer cranks and slower cadences. Two people with identical limb lengths may not be equally efficient with cranks of the same length.


Posted By: GeoffBird
Date Posted: 20 February 2012 at 9:56am
You've introduced another factor to consider Nick! Track sprinters have massive leg muscles, suggesting leg strength is important for this discipline, but not so significant for road racing, perhaps because muscle mass has to be carried up hills and presumably adds to drag?

This is all a bit more complicated than it first seems! A multi-disciplinary study of the issue would be required I think. Having worked with them, I'm sure UK Sport would be interested in this - they're very open-minded.

The fact remains, many people do find a benefit from shorter cranks than conventional wisdom dictates, and, even is there is zero biomechanical benefit, there is still the smaller fairing benefit, which anyone who has designed an HPV fairing will appreciate.


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Right Time - Right Place - Wrong Speed


Posted By: tongskie01
Date Posted: 20 February 2012 at 2:30pm
short cranks good for the knees. developing muscles for every descipline is key. track sprinters=power  road race cyling= both power and endurance. cavendish=excellent sprint finish but rubbish on hills. armstrong=good all rounder.


Posted By: NickM
Date Posted: 20 February 2012 at 8:20pm
Track sprinters have to get their only, rather high, gear going in a hurry from low speed or a standstill, so yes, they do need leg strength. But that is a very specialised scenario, so I think "little relevance" is pretty fair. I should really have said "endurance cycling performance", where "endurance" means any event lasting more than a few minutes.

Mark Cavendish is certainly an endurance athlete. You have to ride 300km before you reach the sprint finish in Milan-San Remo. I suspect that he also goes up hills rather faster than anybody who isn't a professional cyclist more orientated towards ascent. The time cut-offs for elimination in Tour stages are not all that generous.


Posted By: GeoffBird
Date Posted: 20 February 2012 at 8:25pm
Yehbut, Cavendish exceeded the elimination time a couple of time in last year's Tour ;-)

I know - so did a lot of other people (who are probably in the top 500 fittest athletes in the world)...


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Right Time - Right Place - Wrong Speed


Posted By: Warekiwi
Date Posted: 22 February 2012 at 4:24pm
My Grasshopper was supplied with 152mm cranks -Sugino branded. They certainly seem to have saved my knees although initially they took a bit of getting used to. My Quest XL will come with cranks of a similar length as any longer would result in my knees touching the upper skin of the machine.

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QuattroVelo #13 (2016)now eQV!
Snoek#18 Too tight!
Brompton P6- for shoppping!
Vitus Escarpe eMTB for off-road fun.



Posted By: Dave Tigwell
Date Posted: 22 February 2012 at 6:11pm
Hello People, I have noticed that my pedal cadence has come down from 96 to 83 over this off -season`s training as my legs have become stronger. This could indicate a need to run longer cranks at a higher gear perhaps, or is it six of one and half a dozen of the other. However, I`m convinced that this stuff is very particular to the individual rider. Would be interested to hear theories from clever people. Regards, Dave.




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dave T


Posted By: absolute beginner
Date Posted: 22 February 2012 at 9:14pm
Hi All.
I'm quoting from a couple of books I've been reading lately. The first piece regards cadence and the second regards aerobic activity. I hope they are of interest.
 
1- Many new riders tend to underestimate the role of cadence and pedal at around 50-60 rpm, but pro racers won't go below 90 and some no less than 100. This is because mashing a big gear at a low cadence takes the cyclist into anaerobic exercise. A fast cadence in a lower gear consumes less oxygen and puts less stress on the leg muscles and knees.
 
2- Whether it's running, cycling, or a step class, the main reason it gets easier the more you do it, is not because of improved cardiovascular conditioning, but because of improved economy of motion. For the most part, it doesn't get easier because of muscular endurance, but because your body is becoming more efficient at that particular movement. You require less strength and oxygen than you did before, because your body's nervous system is adapting. Wasted movements are eliminated, necessary movements are refined, and muscles that don't need to be tensed are relaxed and eventually atrophied. This is why marathon runners will huff and puff if they cycle for the first time in years.
Aerobic training actually causes muscle wasting because the body is programmed to adapt to whatever demands we place on it. Long low-intensity aerobic training only requires the smallest and weakest, "slow twitch" muscle fibres to fire off again and again. the other, stronger and larger "fast twitch" muscle fibres are not necessary for the task and become a burden to carry and supply with oxygen. The body has no demand for the extra muscle beyond what is needed to perform a relatively easy movement over and over. So your body adapts by burning muscle. Even if you perform steady state training in conjuction with strength training, it will deminish any potential increase in lean body mass, especially in the legs. Aerobic training should only be used to develop movement proficiency when you are traing for a specific sport or event......
 
All the best! 
 


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too fat for too long, time to get fit again!


Posted By: Adrian Setter
Date Posted: 23 February 2012 at 12:42pm
It would be nice to have some some explanation of the theory behind the claim in point 1.  The more generally-accepted wisdom is that high cadence at the same speed requires more oxygen.  See NickM's earlier post, and this, I'm sure, was what Lance Armstrong (who achieved some degree of success riding at a cadence much higher than his rivals) meant when he wrote that it "puts greater demands on the heart and lungs" (or words to that effect).  Reading and personal experience would support the idea that mashing a big gear slowly leads to a greater build up of lactate, not because more oxygen is required but because it restricts blood flow, so less oxygen can get to the muscles.  Armstrong says he adopted his high cadence because it was less fatiguing,
 
For a person who is aready reasonably fit, there might be a lot of truth in point 2.  A lot of stuff about exercise can be counterinuitive, which is why I'll be watching http://www.bbc.co.uk/programmes/b01cywtq" rel="nofollow - next week's Horizon .


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Challenge Hurricane - MicWic Delta (Front half) - Burrows Ratracer


Posted By: tongskie01
Date Posted: 23 February 2012 at 3:08pm
not to forget that venous return of blood to the heart is influenced by muscle contraction.



Posted By: Andrew S
Date Posted: 23 February 2012 at 5:07pm
Originally posted by Dave Tigwell Dave Tigwell wrote:

Hello People, I have noticed that my pedal cadence has come down from 96 to 83 over this off -season`s training as my legs have become stronger.
You're just older now than you were last October, Dave!

Another piece of anecdotal evidence: every morning I do the same run down a flat, straight cycle-track about 1km long. I try to keep one gear lower, i.e. a higher cadence, than I'm really comfortable with because I'm told it's good for me. Sometimes I just can't hold it to the end and change up a gear. Cadence drops but, simultaneously, my speed increases by around 1mph. I know fast cadence is supposed to be better, more efficient or whatever, but it's nuts to that in a race if it slows you down that much. What am I doing wrong??


Posted By: GeoffBird
Date Posted: 23 February 2012 at 8:22pm
A probably sacrilegious and possibly irrelevant comparison:

Petrol-fuelled engines generally produce more power by reving higher (but you have to keep the reciprocating mass low). It's often said that Diesel engines are great because they have much more torque, but they also rev much slower, so need to be geared up, reducing torque at the wheels. The real advantage of Diesels is their even 'spread' of torque across the rev range. Perhaps older bodies are more like diesel engines (sorry Andrew) - they certainly cough and splutter more - and younger bodies more like motorbike engines? Humans and IC engines are after all both heat engines - their efficiency figures are remarkably similar.

People of our age should, however, be reasured that for a number of years, The LeMans 24 Hour race has been won by a diesel-engined car Smile

Martin Widget-Wingnut will hopefully be along in a minute to expand on this comparison, 'cos engines aren't my strong-point.

PS: Good to hear from you Mr Tigwell! Oh, and John - XL Quest? You must be VERY tall.


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Right Time - Right Place - Wrong Speed


Posted By: absolute beginner
Date Posted: 24 February 2012 at 12:15pm
Hi All!
 
Sorry if Quote1 is incorrect or misleading.
 
I have found a piece in Mike Burrows book which is relevant to Quote2 and the relationship between perception and changes of physiological state. Mike writes about meeting Frank Lienhard at the '96 IHPVA Championships.
 
"Frank did not win any races so there were no overnight conversions. Some while later I met Frank riding his regular road-going LB (laid back) also now fitted 110mm cranks, because as Frank discovered, you body/brain take a while to get used to them, and are not so happy about changing back, either. Most surprising though, Frank was going as well as ever, without any aerodynamic benefit other than slightly less air being stirred up by the feet."
 
"taking a while to get used to it" The muscle fibres not needed for turning 110mm cranks are being relaxed to assist increasing effiency of movement.
 
"not so happy about changing back" The muscle fibres not needed are at some stage of the atrophic process. Which when completed would make the change appear permanent.
 
"going as well as ever" The muscle fibre economic requirements are improving the efficiency of movement.
 
Mike goes on to explain how having fitted shorter cranks to his sons' cycle and then his own, he couldn't get used to them because of the number of different bike he was riding at the time. Physiologically Mike's body wouldn't have had time to make the required muscle fibre adjustments to get used to short cranks which may have felt awkward and/or uncomfortable because of the other muscle fibres needed to push varying crank lengths are still being involved in some level of activity.
 
Perception of the benefit of short cranks may just be in the mind. If you have converted, did you change your cadence to match expectation?  Did your knees benefit as result of the shorter crank or the increase in cadence? Did you adjust your gearing needs to help with increase in cadence or were you pushing the same gears for the same/increased speeds?
 
Would we like a study to investigate the time scale associated with the muscle fibre changes required for getting used to short cranks? From relaxation to atrophy, and on to increased efficiency. From initial installation of cranks through to the final result which in some cases racing. A measure of the change of mind too? Is there an optimum crank length or do we just adapt?
 
I do. Frank may already be able to answer this study as he has already undergone his own version.
I am finding the body to be remarkable and adaptable structure. The harmony required between the nervous system and power producing muscle fibres is astounding. I look forward to more debate on this subject. 
 
All the best!
 


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too fat for too long, time to get fit again!


Posted By: tongskie01
Date Posted: 24 February 2012 at 4:46pm
i can certainly say based on my experience that matching the cranks with the leg length can help with knee problems. being 0nly 5'4'' tall i have to changed my crank from 175mm to 155 especially when i started to develop knee pains after doing a lot of hills. this is probably trying to spin faster with longer cranks to keep up speed so that i dont fall over especially on a lowracer.. but i did have to lower down the gear inches coz i could spin faster with the shorter cranks. never had any problems with my knees now.

i believe that the brain senses the pressure that you put on the muscles on every pedal stroke. that is why changing to shorter cranks will feel strange and uncomfortable  at first and may reduce speed. this is due to the fact that short crank=less torque. spinning on same gear i can say,

short crank=more pressure on muscles on each pedal stroke when compared to longer cranks.
so brain tells body gear down to match muscle strength.




Posted By: absolute beginner
Date 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!
 


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too fat for too long, time to get fit again!


Posted By: absolute beginner
Date 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!


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too fat for too long, time to get fit again!


Posted By: johnlucian
Date 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.



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John Lucian


Posted By: tongskie01
Date 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. 


Posted By: absolute beginner
Date 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!
 
 


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too fat for too long, time to get fit again!


Posted By: Dave Tigwell
Date 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.

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dave T


Posted By: absolute beginner
Date 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!


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too fat for too long, time to get fit again!


Posted By: tongskie01
Date 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?



Posted By: cranked forward jim
Date 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!


Posted By: bazz
Date 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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