Dambha Posted June 19, 2020 Share Morning all Is it advisable to use a 172.5 left arm crank with a 175 right crank...got a left arm power metre. In theory could you increase the stack height between your cleats and cycling shoes by using something to make up that 2.5? Any advice would be highly appreciated DieselnDust 1 Link to comment Share on other sites More sharing options...
Butterbean Posted June 19, 2020 Share While a jimmied system might work in theory, just don't do it. Swap the crank arm or buy a new crank to match... Vetplant 1 Link to comment Share on other sites More sharing options...
'Dale Posted June 19, 2020 Share Morning all Is it advisable to use a 172.5 left arm crank with a 175 right crank...got a left arm power metre. In theory could you increase the stack height between your cleats and cycling shoes by using something to make up that 2.5? Any advice would be highly appreciated Not advisable.It's one of the peculiar things in bike fitment where a millimetre becomes a mile and can create injury issues. FirstV8, Me rida my bicycle and Vetplant 3 Link to comment Share on other sites More sharing options...
bertusras Posted June 19, 2020 Share Does stacking it not actually exacerbate the issue though? Let's say you add 2.5mm under your right shoe to the 175mm crank side to 'shorten' it. At the bottom of the stroke you'll be at a relative 172.5mm, spot on, but when you're at the top of the stroke, you will actually be at a relative 177.5mm. Right? Edit: Math is hard. Edited June 19, 2020 by bertusras Capricorn, Vetplant, Quagga and 2 others 5 Link to comment Share on other sites More sharing options...
Vetplant Posted June 19, 2020 Share While a jimmied system might work in theory, just don't do it. Swap the crank arm or buy a new crank to match...Please listen to Guy. Replacing the Crank is much cheaper than the repair cost from the physio/bio. https://bikehub.co.za/classifieds/item/cranksets/408359/shimano-fc-rs510-11-speed-compact-crankset Link to comment Share on other sites More sharing options...
Chris_ Posted June 19, 2020 Share Morning all Is it advisable to use a 172.5 left arm crank with a 175 right crank...got a left arm power metre. In theory could you increase the stack height between your cleats and cycling shoes by using something to make up that 2.5? Any advice would be highly appreciated Then you'll be 5mm out at the top of the pedal stroke... Me rida my bicycle and bertusras 2 Link to comment Share on other sites More sharing options...
DieselnDust Posted June 19, 2020 Share Does stacking it not actually exacerbate the issue though? Let's say you add 2.5mm under your right shoe to the 175mm crank side to 'shorten' it. At the bottom of the stroke you'll be at a relative 172.5mm, spot on, but when you're at the top of the stroke, you will actually be at a relative 177.5mm. Right? Edit: Math is hard. That's why you add the 2.5 spacer to the 175mm side.The effect will always be to have that side 2.5mm higher when the leg is at full extension. its not so much an issue when the leg is under compression Edited June 19, 2020 by DieselnDust Link to comment Share on other sites More sharing options...
100Tours Posted June 19, 2020 Share That's why you add the 2.5 spacer to the 172.5mm side..... Nope - Bertus is right here. The bigger impact of changing crank length (imho) is how high you have to lift your leg at the top of your stroke to get it over the hump. if you have built up the shoe your foot is going to have to clear a higher hump to get around the loop - the bottom of the stroke is less of an issue (you fix that with seat height). DieselnDust 1 Link to comment Share on other sites More sharing options...
DieselnDust Posted June 19, 2020 Share Morning all Is it advisable to use a 172.5 left arm crank with a 175 right crank...got a left arm power metre. In theory could you increase the stack height between your cleats and cycling shoes by using something to make up that 2.5? Any advice would be highly appreciated 2.5mm is within a normal leg length discrepancy. Technically you can get away with it if you fit a spacer under the shoe connected to the 175mm crank arm. However......... What if the other leg is the one that requires correction and you now exaggerate the leg length discrepancy? Vetplant 1 Link to comment Share on other sites More sharing options...
DieselnDust Posted June 19, 2020 Share Nope - Bertus is right here. The bigger impact of changing crank length (imho) is how high you have to lift your leg at the top of your stroke to get it over the hump. if you have built up the shoe your foot is going to have to clear a higher hump to get around the loop - the bottom of the stroke is less of an issue (you fix that with seat height). ya sorry was thinking about the 175mm crankarm and typed 172.5mm. Corrected post Link to comment Share on other sites More sharing options...
LuckyLuke Posted June 19, 2020 Share Go for a bike fit, usually your left leg is bit shorter than the right, then it probably wont be an issue and my fitter agreed, i was going the same direction but got a powertap wheel for cheap Edited June 19, 2020 by devilliers Link to comment Share on other sites More sharing options...
Long Wheel Base Posted June 19, 2020 Share So if you do the 2.5mm spacer thing on the shoe, when at 90deg(crank), you are 172.5mm away from the centre but you a small amount above or below 90deg(foot) in reality? Waiting for all the biopace/Qring/sqaushed chainring guys to start with how this can improve power or pedal stroke or whatever it is these things do. DieselnDust 1 Link to comment Share on other sites More sharing options...
Quagga Posted June 19, 2020 Share That's why you add the 2.5 spacer to the 175mm side.The effect will always be to have that side 2.5mm higher when the leg is at full extension. its not so much an issue when the leg is under compressionDisagree, the angle of the hip will be less putting strain on lower back and Glute Link to comment Share on other sites More sharing options...
Kalahari Vegmot Posted June 19, 2020 Share Seems like a decent idea mind you. 2.5mm is really nothing; just bend the saddle to even the legs out that little bit and you'll be golden???????? Veebee, Jewbacca and Wayne pudding Mol 3 Link to comment Share on other sites More sharing options...
thebob Posted June 19, 2020 Share Sounds like a shortcut to a world of pain gummibear, The Ouzo, Quagga and 1 other 4 Link to comment Share on other sites More sharing options...
Wayne pudding Mol Posted June 19, 2020 Share Do it and report back in 1000kms and we can publish a paper Disclaimer - I am in no way responsible for any medical bills Quagga, Veebee, throttles and 3 others 6 Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now