Replacing a crankset
#51
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I tried a 165mm COTTERED double crank from a Japanese 10 speed I had laying around to ascertain the correct length. It took maybe 20-30 minutes to install.
I then ordered my 165mm triple once I discovered 165mm was for me.
TEST TEST TEST before you commit.
BTW- I made up a temporary cadence sensor to also help measure results. That's how I know 160mm didn't really give me but 3 RPM more than 165's and simply didn't "feel" good.
https://www.instructables.com/Very-E...-Your-Bike-12/
I then ordered my 165mm triple once I discovered 165mm was for me.
TEST TEST TEST before you commit.
BTW- I made up a temporary cadence sensor to also help measure results. That's how I know 160mm didn't really give me but 3 RPM more than 165's and simply didn't "feel" good.
https://www.instructables.com/Very-E...-Your-Bike-12/
#52
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One issue that VegasJen has not yet considered is how would a new contemporary crank (either the inexpensive 12-speed one I linked above or an 11-speed model) work with her existing 9 or 10-speed drivetrains. Lots of variables there.
For example, I use 10-speed Shimano chain rings with an otherwise 11-speed Shimano drive train without issues, but she needs something else.
For example, I use 10-speed Shimano chain rings with an otherwise 11-speed Shimano drive train without issues, but she needs something else.
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One issue that VegasJen has not yet considered is how would a new contemporary crank (either the inexpensive 12-speed one I linked above or an 11-speed model) work with her existing 9 or 10-speed drivetrains. Lots of variables there.
For example, I use 10-speed Shimano chain rings with an otherwise 11-speed Shimano drive train without issues, but she needs something else.
For example, I use 10-speed Shimano chain rings with an otherwise 11-speed Shimano drive train without issues, but she needs something else.
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So, you think, for example, that a 9-speed chain would work with a 12-speed crankset? I am not disagreeing, I just don't know; I had thought that the gap between chain rings in a 2x crankset is somewhat dependent on the chain.
#56
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I also don't know. But higher speed systems have everything thinner (and thus less durable, given the same material quality). So an older system like a 9 chain on 12 cogs and chainrings, I think the wider outside width of the 9 chain may be a problem on a 12 cassette with noise and possible unintended upshifts, and the wider inside diameter may be a problem on a 12 chainring as it may be less stable, may want to twist slightly.
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No way is a 9speed chain fitting a 12speed cassette. There's a >1mm difference in chain width.
edit: I need to read more carefully.
edit: I need to read more carefully.
Last edited by choddo; 01-31-24 at 10:21 AM.
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9+ cassette with 11 speed crank, i expect that it'll be ok. I haven't put raw numbers together to establish a professional data sheet, but even then a real world test can reveal different outcomes that calculated data might not factor.
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#59
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if it were an eight speed cassette, I'd paint a different picture with my thoughts.
9+ cassette with 11 speed crank, i expect that it'll be ok. I haven't put raw numbers together to establish a professional data sheet, but even then a real world test can reveal different outcomes that calculated data might not factor.
9+ cassette with 11 speed crank, i expect that it'll be ok. I haven't put raw numbers together to establish a professional data sheet, but even then a real world test can reveal different outcomes that calculated data might not factor.
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on the subject of the Shimano bonded cranks - comparison of the bonded vs bonded / machined etc - great article on 6800 vs 5800 cranks - includes pictures and weights :
https://handsonbike.blogspot.com/201...o-105.html?m=1
.
Last edited by t2p; 01-31-24 at 09:31 AM.
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Yes, a 9 speed chain will work on a 12 speed crankset. The distance between rings on a crankset aren’t narrower, although the ring itself is narrower. The width of a chain is dependent on the cassette spacing, not on the crank.
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I also don't know. But higher speed systems have everything thinner (and thus less durable, given the same material quality). So an older system like a 9 chain on 12 cogs and chainrings, I think the wider outside width of the 9 chain may be a problem on a 12 cassette with noise and possible unintended upshifts, and the wider inside diameter may be a problem on a 12 chainring as it may be less stable, may want to twist slightly.
if it were an eight speed cassette, I'd paint a different picture with my thoughts.
9+ cassette with 11 speed crank, i expect that it'll be ok. I haven't put raw numbers together to establish a professional data sheet, but even then a real world test can reveal different outcomes that calculated data might not factor.
9+ cassette with 11 speed crank, i expect that it'll be ok. I haven't put raw numbers together to establish a professional data sheet, but even then a real world test can reveal different outcomes that calculated data might not factor.
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This is at the bottom of the crank stroke.
The thing I notice is this is as high as I can have my seat position without rocking my hips, which is all but slammed on the seat tube. But just looking at the pictures, it seems like I'm making too big of circles through the arc of travel. My leg is nearly locked at the bottom of the stroke and my hip angle is very acute at the top. I could probably go down to 155 or even 150 but I'm probably going to go with 160 simply for availability if I can't get shorter crank arms that work on this set.
The thing I notice is this is as high as I can have my seat position without rocking my hips, which is all but slammed on the seat tube. But just looking at the pictures, it seems like I'm making too big of circles through the arc of travel. My leg is nearly locked at the bottom of the stroke and my hip angle is very acute at the top. I could probably go down to 155 or even 150 but I'm probably going to go with 160 simply for availability if I can't get shorter crank arms that work on this set.
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Another rant on this subject: Now that everyone and his brother…emphasis on the “his” and “brother” part…has discovered short cranks it’s amazing that they are starting to become available. Half the population could have benefitted from shorter cranks for the last 125+ years but bike manufacturers have a very long history of ignoring the needs of that half of the population.
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If there was a lack of provision for female cyclists, it was all for their own protection from bicycle face
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Nope. The tandem is the proper size for her. In fact, I was rather surprised that tandems came in a stoker size that was actually her size. She rides a 43cm road bike with 700C or 26” wheels. This frame is the same size. She has about as much seatpost showing as I do and the captain frame is exactly my size.
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Don’t know. I haven’t run across any if they were. There’s lots of short Ashtabula cranks but it’s not like those can be used on that many bikes.
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#70
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on the subject of the Shimano bonded cranks - comparison of the bonded vs bonded / machined etc - great article on 6800 vs 5800 cranks - includes pictures and weights :
https://handsonbike.blogspot.com/201...o-105.html?m=1
.
- For the ultegra spider, outer shell bonded to inner part, are they both aluminum parts or is one steel? If both aluminum, I can't see the advantage of bonding two parts together, versus the one-piece 105 spider, with both appearing to be same finished shape, especially at such small mass difference.
- Both ultegra and 105 outer rings show significant "depth of section", thicker, versus traditional rings. I wonder if it's to allow them to be lighter (ultegra is hollow, 105 uses a composite ribbed construction), or they did it to make the rings laterally stiffer (versus traditional rings), for greater shift precision?
Last edited by Duragrouch; 02-01-24 at 01:31 AM.
#72
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Good edit. That's typical. I just can't figure out why they would bond two pieces of aluminum together, to get the same net shape and near identical mass as the 1-piece cast aluminum 105 spider and crankarm. UNLESS... it's 2-piece to make the arm hollow? But it's only 9 grams lighter. Maybe the ultegra came first to market with that style, then later with the 105, they decided to be a bit less clever, make it 1-piece?
Last edited by Duragrouch; 02-01-24 at 02:24 AM.
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Good edit. That's typical. I just can't figure out why they would bond two pieces of aluminum together, to get the same net shape and near identical mass as the 1-piece cast aluminum 105 spider and crankarm. UNLESS... it's 2-piece to make the arm hollow? But it's only 9 grams lighter. Maybe the ultegra came first to market with that style, then later with the 105, they decided to be a bit less clever, make it 1-piece?
would like to see a CNC/waterjet cut aluminum assembly made using a thicker spindle shaft [ I.D. increase] that allows for two crank gears to be affixed to it using titanium hardware. would not want to see that price tag though!
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I have contacted Bikesmith and he is recommending a 150mm crankset. He has one available, but I have to admit, that big of a jump kind of scares me a little bit. I was thinking 160, or maybe down to 155mm. I'm probably going to go with it, especially since this is for the TT bike. If I like it, I'm probably going to go smaller on my road bikes, but may only go to 160 on them.
The amount you shorten the crankarms, you will need to raise your saddle a similar distance. This will also change the rest of your fit.
at 5'4" 150-160mm should work for you. It's all about the inseam.
Closer to 150mm for road and closer to 160 for MTB
You'll likely notice a higher cadence and less hip sway and maybe less saddle sores
Gearing might have to be adjusted depending how picky you are.
I'm only slightly taller than you and went from 170 and 175 and shortened them to 150 and 155. Later adjusted to 160-165 when I upgraded
I was going to go on a rant about crankarm shortening but the engineering nerds covered most of it, and it looks like you don't need it.
Final note:
If anyone uses BMX cranksets use caution
The chainline is usually around 43-45mm and not really suitable with most ROAD and MTB frames.
You may have skipped the internal pressfit era completely by doing that. They're all switching to T47 threaded now. The bearings are still pressfit though, into cups which are threaded. https://wheelsmfg.com/blog/what-is-a...m-bracket.html (blog post is a bit old)
A lot to be said for keeping things maintainable. Someone expressed shock at my lack of electronic shifting and disc brakes on my 2019 bike at the weekend
A lot to be said for keeping things maintainable. Someone expressed shock at my lack of electronic shifting and disc brakes on my 2019 bike at the weekend
#75
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You may have skipped the internal pressfit era completely by doing that. They're all switching to T47 threaded now. The bearings are still pressfit though, into cups which are threaded. https://wheelsmfg.com/blog/what-is-a...m-bracket.html (blog post is a bit old)
A lot to be said for keeping things maintainable. Someone expressed shock at my lack of electronic shifting and disc brakes on my 2019 bike at the weekend
A lot to be said for keeping things maintainable. Someone expressed shock at my lack of electronic shifting and disc brakes on my 2019 bike at the weekend