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Super Sport 3 piece
Taking some time to mock up this bike before spring repaint. Had this bmx crank and was hopeing to use on this build. Concern is the distance from bottom bracket to 1st ring. Small-big makes for quite the chain angle. On the trainer derailers hit all gears. Looking for thoughts on this chain line.
https://cimg0.ibsrv.net/gimg/bikefor...651e53fdf.jpeg https://cimg3.ibsrv.net/gimg/bikefor...687b493e3.jpeg https://cimg4.ibsrv.net/gimg/bikefor...668913702.jpeg https://cimg0.ibsrv.net/gimg/bikefor...7f0089df8.jpeg https://cimg6.ibsrv.net/gimg/bikefor...d0de53ed9.jpeg |
Thanks for the detailed pictures. It looks like it could be good. I like the bike and the components shown.
I usually put the chain on the middle cog of the freewheel and sight from the rear along the chain to see if there is an "s" bend in the chain. For a triple chain ring the chain would be on the middle chainring. For a double, I check both chainrings. The chain line may not be perfect, but it should be close. Perhaps you you can get us that picture? I wouldn't mind seeing more details of the frame too (unless it is already on another thread). Eye candy, a naked fillet blazed frame. |
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drive side of spindle definitely too long think of the Q factor as well... ----- |
Measure from between the two chainrings and the middle of the seat tube. Should be be in the 42-45mm range.
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Didn’t give q a thought. Hurt the knee,right? More I look at it compared to other bikes,it doesn’t look right. I’m good with Ashtabula one piece,just thought this set up might have worked. Couple pics of the brazing for Velo mule.
https://cimg1.ibsrv.net/gimg/bikefor...7d4454d73.jpeg https://cimg3.ibsrv.net/gimg/bikefor...33f81b967.jpeg |
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I have never had one of those Ashtabula-to-square conversion bottom brackets pass through my hands that didn't have a REALLY long (like around 135mm) spindle, so never used one.
The Takagi XT triple cranks came fitted to some unusually-long spindles, so might be the best crank choice with one of these bb's. I usually set up vintage doubles with a 6s freewheel and try to achieve a 45mm "chainline" measured from the center of theseat tube to the center of the LARGE chainring. This just works best for the way that I ride, mostly in the big ring, but also using the small chainring with the largest four or possibly five cogs only. I recently went to quite a bit of trouble (tested three bottom brackets) to reduce the distance to the large chainring from 48mm to 44mm, using a symmetrical 107mm JIS bottom bracket with a Sugino Mighty Tour crankset. There is now a big improvement in my ability to use the full range of six cogs while on the big ring, with an absolute minimum in of "cross-chaining" noise. There are no drawbacks, though the chainring bolts are now close to the chainstay and the chain clinks along the big ring's inner side as a useful reminder when I ride in the (36/)15t cog (second one in). |
2-1/8" x 24.4 = 54mm.
Thanks for the pictures of the fillets. They look nice. If I ever get a Super Sport or Sports Tourer, it would have to be in such shape that it requires a paint job, because 1. I would like to see all the fillets, filing and sanding and 2. I'm pretty good at painting. I wouldn't be wasting a good original frame just to satisfy my curiosity. |
Originally Posted by Kdogbikes
(Post 21380220)
Taking some time to mock up this bike before spring repaint. Had this bmx crank and was hopeing to use on this build. Concern is the distance from bottom bracket to 1st ring. Small-big makes for quite the chain angle. On the trainer derailers hit all gears. Looking for thoughts on this chain line.
That looks like a press-fit adaptor in an ashtabula shell. Can you flip the axle end-for-end, might be a better fit. Otherwise you need a shorter axle on the crank side somehow. |
It looked a little too far out. Numbers back it up for chainline friction.
Beautiful frame you have there! |
Thanks for the comments. Bummed won’t work as the Altus front derailer fits the ss seat tube! Well, with a wee bit of fileing....Bought this donor bike with nice chrome bits that’ll work just fine. Cheers, Kevin
https://cimg7.ibsrv.net/gimg/bikefor...4f4beefc7.jpeg |
O.M.A.S. and others made bolt-in adaptors that take a conventional threaded bottom bracket, cartridge or standard. This one is missing one of the four bolts. Apologies for the focus.
https://cimg4.ibsrv.net/gimg/bikefor...731bd44370.jpg |
I have a Super Sport that I'll be using a 3-piece crank on. I'll be using a BMX crank adapter like this:
https://www.amazon.com/Truvativ-00-6.../dp/B000VT550K so I can use any cartridge bottom bracket I like and set up the chainline correctly. |
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