64 BCD chainring onto 104 BCD spider?
#1
64 BCD chainring onto 104 BCD spider?
I have a triple crankset. I love wide gearing as i climb a lot. However, i wasn't really happy with my current setup which consists of 28T, 38T and 48T chainrings in combination with an 11 to 32 cassette at the back. So i did something stupid, and without carefully inspecting my crank arms, i purchased three chainrings from China. 22T (64BCD), 32T and 42T (104BCD). They arrived and just as i was gonna install them, i realized that my crankset did not have the inner 64BCD bolt holes. Like i said, it is a triple crankset but the problem is, the medium and small chainrings were "riveted" to each other. Now i can install the 32T and 42T just fine, my crank arm has the 104BCD holes, but it can't really be much of an upgrade without installing the 22T.
So my question to you experienced tinkerers out there: Do i have to buy a new pair of crank arms with 64bcd holes as well, or is there something else that i can do and modify my current crank arm to accommodate the 22T chainring?
Thanks a lot.
PS: My initial idea was to get something like this. I think this is a 64 to 104 adapter. However, i think it will create a larger gap between the two bigger chainrings and the shifting won't work.
So my question to you experienced tinkerers out there: Do i have to buy a new pair of crank arms with 64bcd holes as well, or is there something else that i can do and modify my current crank arm to accommodate the 22T chainring?
Thanks a lot.
PS: My initial idea was to get something like this. I think this is a 64 to 104 adapter. However, i think it will create a larger gap between the two bigger chainrings and the shifting won't work.
#2
Senior Member
I have a triple crankset. I love wide gearing as i climb a lot. However, i wasn't really happy with my current setup which consists of 28T, 38T and 48T chainrings in combination with an 11 to 32 cassette at the back. So i did something stupid, and without carefully inspecting my crank arms, i purchased three chainrings from China. 22T (64BCD), 32T and 42T (104BCD). They arrived and just as i was gonna install them, i realized that my crankset did not have the inner 64BCD bolt holes. Like i said, it is a triple crankset but the problem is, the medium and small chainrings were "riveted" to each other. Now i can install the 32T and 42T just fine, my crank arm has the 104BCD holes, but it can't really be much of an upgrade without installing the 22T.
So my question to you experienced tinkerers out there: Do i have to buy a new pair of crank arms with 64bcd holes as well, or is there something else that i can do and modify my current crank arm to accommodate the 22T chainring?
Thanks a lot.
PS: My initial idea was to get something like this. I think this is a 64 to 104 adapter. However, i think it will create a larger gap between the two bigger chainrings and the shifting won't work.
So my question to you experienced tinkerers out there: Do i have to buy a new pair of crank arms with 64bcd holes as well, or is there something else that i can do and modify my current crank arm to accommodate the 22T chainring?
Thanks a lot.
PS: My initial idea was to get something like this. I think this is a 64 to 104 adapter. However, i think it will create a larger gap between the two bigger chainrings and the shifting won't work.
If your crank does not have a removable spider, then trying to attach a removable spider through the matching bolt holes would most likely not fit.
If you're wanting to get 64mm bcd holes onto your crank, you could think about laser cutting a steel or aluminum plate to be attached flush with the outside of your outer chainring, with both 104 and 64mm bcd holes cut out of it. The 2 circles of holes would have to be arranged some degrees turned from each other so that the 64mm bcd holes clear the flange and the crank arm. Then you'd need something like 16mm of spacers and very long chainring bolts between the 22t chainring and the laser cut plate.
Last edited by tomtomtom123; 12-27-19 at 02:48 AM.
#3
It would help if you described what model crank you have, and what kind of flange is uses. If it's like this removable spider that's designed to fit your model of crank, that you've pictured, then I don't see why it would not work. What is the reason why you think it wouldn't work?
If your crank does not have a removable spider, then trying to attach a removable spider through the matching bolt holes would most likely not fit.
If you're wanting to get 64mm bcd holes onto your crank, you could think about laser cutting a steel or aluminum plate to be attached flush with the outside of your outer chainring, with both 104 and 64mm bcd holes cut out of it. The 2 circles of holes would have to be arranged some degrees turned from each other so that the 64mm bcd holes clear the flange and the crank arm. Then you'd need something like 16mm of spacers and very long chainring bolts between the 22t chainring and the laser cut plate.
If your crank does not have a removable spider, then trying to attach a removable spider through the matching bolt holes would most likely not fit.
If you're wanting to get 64mm bcd holes onto your crank, you could think about laser cutting a steel or aluminum plate to be attached flush with the outside of your outer chainring, with both 104 and 64mm bcd holes cut out of it. The 2 circles of holes would have to be arranged some degrees turned from each other so that the 64mm bcd holes clear the flange and the crank arm. Then you'd need something like 16mm of spacers and very long chainring bolts between the 22t chainring and the laser cut plate.
Last edited by Newspaper_Nick; 12-27-19 at 04:30 AM.
#4
Senior Member
The laser cut idea is like having a 104mm bcd bashguard on the outside, but with an extra set of 64mm holes that you can bolt the inner chainring to, with very long bolts and spacers. You have to rotate the holes so that the flange and crank arm doesn't get in the way of the holes. Laser cutting is maybe $30. You have to make a dxf drawing to a laser cutter provider. They supply the metal plates on their Automatic cutting machines
#5
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That's a direct mount spider and not going to help you.
Honestly I'd just bite the bullet and spend the money on a different $30 crank W/22/32/42 installed and chalk it up to a life lesson. Worst case you also need to buy a $10 UN 26 or $15 UN 55 bottom bracket of the correct 122.5mm spindle length, but I'd guess your existing BB spindle will be close. Before you buy a BB you need to do some measurements to avoid a similiar issue of compatibility.
https://www.jensonusa.com/Shimano-Ac...quare-Crankset
https://www.jensonusa.com/Shimano-UN-26-Bottom-Bracket
Last edited by dedhed; 12-27-19 at 07:01 AM.
#7
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Be aware, the crankset chosen determines what bottom bracket (BB) type or spindle length you will need for it to install for intended chainline. First measure your BB shell width.It'll most likely be 68mm or 73mm, most likely English threaded given the crank on it now. If you get another sq taper crank see what spindle length the new crank requires. Measure your old spindle length and maybe you won't need a new BB. Really though if you have some miles on the bike you might just replace it anyway and keep the old one for a spare. If you have a coop, nearby you may be able to pick up a used crank cheap that will use the chain rings you already bought or have good rings you prefer already on it.
#8
Be aware, the crankset chosen determines what bottom bracket (BB) type or spindle length you will need for it to install for intended chainline. First measure your BB shell width.It'll most likely be 68mm or 73mm, most likely English threaded given the crank on it now. If you get another sq taper crank see what spindle length the new crank requires. Measure your old spindle length and maybe you won't need a new BB. Really though if you have some miles on the bike you might just replace it anyway and keep the old one for a spare. If you have a coop, nearby you may be able to pick up a used crank cheap that will use the chain rings you already bought or have good rings you prefer already on it.
Last edited by Newspaper_Nick; 12-31-19 at 08:24 AM.
#9
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Thanks for the heads up. My bottom bracket shell is 68mm. And my spindle length is 122.5mm. I purchased the following crankset for a good price (hopefully it will arrive in a month). It already has the chainring sizes that i wanted. The chainrings i purchased previously will also fit this so i will keep them as spares. I like having spares
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#10
#11
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If it was my bike and you're not in too much of a hurry, I'd wait for the crankset to come in and test fit the new crankset to your existing spindle. That way you can see if your front derailleur will reach the biggest chainring or not (my bet}.
If you are a chainline purist you can hold a straight edge against the middle chainring and see how closely it comes to bisecting your cassette. If you're more like me, you'll just eyeball how far you think you need to move the chainrings inward and buy a BB with a spindle short enough to do that. It doesn't have to be perfect. If you're a risk taker you'll probably need something in the 112mm to 116mm range. The lowest cost solution is to find a donor bike so you can hunt around while you're waiting for the crankset.
Don't forget that BB spindles have two ends. In most (but not all) cases, if you want to move your chainrings inward 5mm you'll need a BB spindle that's 10mm shorter.
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My greatest fear is all of my kids standing around my coffin and talking about "how sensible" dad was.
My greatest fear is all of my kids standing around my coffin and talking about "how sensible" dad was.
#12
122.5 is a pretty old but common spec. Newer cranksets tend to have more offset and consequently require shorter BB spindles.
If it was my bike and you're not in too much of a hurry, I'd wait for the crankset to come in and test fit the new crankset to your existing spindle. That way you can see if your front derailleur will reach the biggest chainring or not (my bet}.
If you are a chainline purist you can hold a straight edge against the middle chainring and see how closely it comes to bisecting your cassette. If you're more like me, you'll just eyeball how far you think you need to move the chainrings inward and buy a BB with a spindle short enough to do that. It doesn't have to be perfect. If you're a risk taker you'll probably need something in the 112mm to 116mm range. The lowest cost solution is to find a donor bike so you can hunt around while you're waiting for the crankset.
Don't forget that BB spindles have two ends. In most (but not all) cases, if you want to move your chainrings inward 5mm you'll need a BB spindle that's 10mm shorter.
If it was my bike and you're not in too much of a hurry, I'd wait for the crankset to come in and test fit the new crankset to your existing spindle. That way you can see if your front derailleur will reach the biggest chainring or not (my bet}.
If you are a chainline purist you can hold a straight edge against the middle chainring and see how closely it comes to bisecting your cassette. If you're more like me, you'll just eyeball how far you think you need to move the chainrings inward and buy a BB with a spindle short enough to do that. It doesn't have to be perfect. If you're a risk taker you'll probably need something in the 112mm to 116mm range. The lowest cost solution is to find a donor bike so you can hunt around while you're waiting for the crankset.
Don't forget that BB spindles have two ends. In most (but not all) cases, if you want to move your chainrings inward 5mm you'll need a BB spindle that's 10mm shorter.
#13
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I wouldn't be surprised if it takes a 113mm
#14