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45mm chainline crank suggestions

Old 11-17-23, 12:03 PM
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Think I might make a trip to the local bike co-op and see if I can hunt down a 110 or 107mm Shimano or Tange bottom bracket and see how they fit. Rather not play with the dishing and spacing too much for fear of creating an issue with clearance between the dropout and chain.
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Old 11-17-23, 12:16 PM
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Originally Posted by boneshaker78
Think I might make a trip to the local bike co-op and see if I can hunt down a 110 or 107mm Shimano or Tange bottom bracket and see how they fit. Rather not play with the dishing and spacing too much for fear of creating an issue with clearance between the dropout and chain.
Data I've seen shows 107 & 110 has same DS lengths. Shimano @20 for both, Tange @20.5. Other brand?, haven't really done much searching.
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Old 11-17-23, 12:33 PM
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Originally Posted by KCT1986
Data I've seen shows 107 & 110 has same DS lengths. Shimano @20 for both, Tange @20.5. Other brand?, haven't really done much searching.
Very helpful. Thanks
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Old 11-24-23, 02:10 PM
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Just tried 107mm bottom bracket Shimano and got a 43.5mm chainline, the drive side crank arm was going to actually contact the bottom bracket so I had to stop. The crank arm was definitely close to being fully mounted so the chainline wasn’t going to change much at that point. 107mm will definitely not work.

118mm when fully mounted gave me 50mm chainline.

Based on this information that leaves me with 115mm and 113mm, 110mm has the same drive side length as the 107mm so that won’t work.

113mm sounds like my best option. Interested to hear some opinions.

I really wish bottom bracket lengths and chainline were a lot easier to calculate. Pains me to mount square taper two or three times before getting it right. 😢

Last edited by boneshaker78; 11-24-23 at 02:19 PM.
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Old 11-24-23, 07:53 PM
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Originally Posted by boneshaker78
Just tried 107mm bottom bracket Shimano and got a 43.5mm chainline, the drive side crank arm was going to actually contact the bottom bracket so I had to stop. The crank arm was definitely close to being fully mounted so the chainline wasnít going to change much at that point. 107mm will definitely not work.

118mm when fully mounted gave me 50mm chainline.

Based on this information that leaves me with 115mm and 113mm, 110mm has the same drive side length as the 107mm so that wonít work.

113mm sounds like my best option. Interested to hear some opinions.

I really wish bottom bracket lengths and chainline were a lot easier to calculate. Pains me to mount square taper two or three times before getting it right. 😢
If you are getting a 50mm CL w/ the 118 BB, then the crank is probably designed to take a 113mm BB for a 47.5 CL.

Just need to verify that the frame has clearance for the chainrings & crankarms w/ the 113mm.
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Old 11-24-23, 08:00 PM
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Originally Posted by KCT1986
If you are getting a 50mm CL w/ the 118 BB, then the crank is probably designed to take a 113mm BB for a 47.5 CL.

Just need to verify that the frame has clearance for the chainrings & crankarms w/ the 113mm.
That seems correct. Iíll be interested to see what chainline I get, but I bet youíre right and it will be 47.5mm. Not ideal, but maybe I can make it work by shifting the cassette some and settling on the difference. Too bad they donít make a bottom bracket length somewhere inbetween 107/110mm and 113mm. ☹️

There will be plenty of clearance at the chainstays because surprisingly the 107mm, that gave roughly 43mm chainline, allowed for plenty of space to be mounted.
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Old 11-24-23, 08:43 PM
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Originally Posted by boneshaker78
That seems correct. Iíll be interested to see what chainline I get, but I bet youíre right and it will be 47.5mm. Not ideal, but maybe I can make it work by shifting the cassette some and settling on the difference. Too bad they donít make a bottom bracket length somewhere inbetween 107/110mm and 113mm. ☹️

There will be plenty of clearance at the chainstays because surprisingly the 107mm, that gave roughly 43mm chainline, allowed for plenty of space to be mounted.
The 113 (47.5) & 118 (50) options for BB was another design that Shimano used, along with the 110/113 design as mentioned earlier.

The rear chainline can be changed either with cone/spacer/lockring manipulation and/or the use of spacers behind the cassette, as long as the outermost sprocket can engage the splines of the freehub body & the lockring has reasonable purchase.
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Old 12-02-23, 04:47 PM
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I installed the crankset, torqued to 30 ft lbs, I got what appears to be 48.5 chainline using a 113mm bottom bracket and the Shimano A10 crankset. I have 47.5 on the rear axle, so I guess within one mm is close enough. I do question whether or not the middle chainring should have spacers, maybe that is where the extra mm should be coming from. The distance between chainrings looks smaller between the largest and the middle compared to the middle and the smallest.

The rear wheel hasn’t been built yet and the cassette was installed loosely while I mocked up the derailleurs, set everything up to see how things will operate.

Everything looks good, the chain does come close to the dropout, but I have to keep in mind the cassette isn’t fully installed yet, it will be pulled away from it once it is snugged down.

The rear derailleur has plenty of room on the limit screws, but the front derailleur seems to barely clear in the high position (on the big ring). Maybe I’m missing something but I let the high screw out all the way, I’m glad there’s at least a mm clearance but that’s all, won’t go out any further.

Happy it appears that it will work. Thanks for the help everyone.





Last edited by boneshaker78; 12-02-23 at 05:02 PM.
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Old 12-02-23, 09:29 PM
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Originally Posted by boneshaker78
I installed the crankset, torqued to 30 ft lbs, I got what appears to be 48.5 chainline using a 113mm bottom bracket and the Shimano A10 crankset. I have 47.5 on the rear axle, so I guess within one mm is close enough. I do question whether or not the middle chainring should have spacers, maybe that is where the extra mm should be coming from. The distance between chainrings looks smaller between the largest and the middle compared to the middle and the smallest.

The rear wheel hasn’t been built yet and the cassette was installed loosely while I mocked up the derailleurs, set everything up to see how things will operate.

Everything looks good, the chain does come close to the dropout, but I have to keep in mind the cassette isn’t fully installed yet, it will be pulled away from it once it is snugged down.

The rear derailleur has plenty of room on the limit screws, but the front derailleur seems to barely clear in the high position (on the big ring). Maybe I’m missing something but I let the high screw out all the way, I’m glad there’s at least a mm clearance but that’s all, won’t go out any further.

Happy it appears that it will work. Thanks for the help everyone.



It's surprising that the FD is having problems w/ 48 chainline, most of Shimano MTB FD has much more range, usually out to 55 or more.

Pull on the FD cable along the downtube to see if it can move out further, (assuming you have the correct limit screw loosened).

The other consideration is if your shifter is pulling enough cable to match the FD actuation ratio. Don't know what type of FD those shifters were designed for.

During set-up, most triples use a cable tension that is set with the chain on the middle chainring and largest sprocket. Minimum clearance of the chain and inner cage plate in this position. At this tension, the FD should be centered over the crankset and allow the proper shifting to all 3 rings & most useable F/R gear combos (assuming the shifter pull is correct for the FD).
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Old 12-02-23, 09:34 PM
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Originally Posted by KCT1986
It's surprising that the FD is having problems w/ 48 chainline, most of Shimano MTB FD has much more range, usually out to 55 or more.

Pull on the FD cable along the downtube to see if it can move out further, (assuming you have the correct limit screw loosened).

The other consideration is if your shifter is pulling enough cable to match the FD actuation ratio. Don't know what type of FD those shifters were designed for.

During set-up, most triples use a cable tension that is set with the chain on the middle chainring and largest sprocket. Minimum clearance of the chain and inner cage plate in this position. At this tension, the FD should be centered over the crankset and allow the proper shifting to all 3 rings & most useable F/R gear combos (assuming the shifter pull is correct for the FD).
Thank you. I’ll have to take another look.

I admit my derailleur knowledge is somewhat limited. I spent a lot of time riding singlespeeds and fixed for years.

I should run through a proper setting up of the front derailleur. The shifters are Gripshift 400 FFS.

Last edited by boneshaker78; 12-02-23 at 09:41 PM.
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Old 12-04-23, 12:04 PM
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Finished today.

The front derailleur is working well now, plenty of clearance for the largest chainring. I made the cable tighter by using the barrel adjuster and that seemed to help. Everything seems to be working well.

28.6 lbs is not light, but this bike is intended for use in situations where security might be an issue. I tried to build it as cheap as I could while being mechanically sound. I over did it a little IMO at $300, but I’m happy with the results.

Thank you everyone! I learn so much on BF and really appreciate having this resource.



Last edited by boneshaker78; 12-04-23 at 12:07 PM.
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Old 12-04-23, 02:27 PM
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Originally Posted by boneshaker78
Finished today.

The front derailleur is working well now, plenty of clearance for the largest chainring. I made the cable tighter by using the barrel adjuster and that seemed to help. Everything seems to be working well.

28.6 lbs is not light, but this bike is intended for use in situations where security might be an issue. I tried to build it as cheap as I could while being mechanically sound. I over did it a little IMO at $300, but Iím happy with the results.

Thank you everyone! I learn so much on BF and really appreciate having this resource.

Glad that you got it done. The FD should work with proper setup.

The cable tension should be set as previously mentioned. Tweak as necessary based on how the shifter/FD interacts to get the best combos of gearing that run quietly based on your usage.

Now how to keep your shiny bike from being stolen. Thieves are attracted to 'shiny' objects.
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Old 12-04-23, 02:46 PM
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Originally Posted by KCT1986
Glad that you got it done. The FD should work with proper setup.

The cable tension should be set as previously mentioned. Tweak as necessary based on how the shifter/FD interacts to get the best combos of gearing that run quietly based on your usage.

Now how to keep your shiny bike from being stolen. Thieves are attracted to 'shiny' objects.
You’re right… it’s my curse. I can’t help but make a bike as clean as possible. I’ll have to lower the saddle and find some mud puddles!
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