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Cottered Crank Tripilizer, DIY
I'm in the process of overhauling my exceedingly awesome Raleigh Super Course, but, to be honest, there is nothing all that unique about mine as they are all exceedingly awesome, at any rate, I'm going to be riding this bike in Eroica in april, and I hear the hills are STEEP!!!! and I hate walking, and I like tinkering, and the stock 40/28 gearing on this bike is the completely uncorrect gearing for such a ride, so I'm working on a tripilizer. I may well end up doing some walking even with the tripilizer, but at least this gives me a better chance of not walking.
The spacers between the stock chain rings are 1/8" thick, and I have some 1/8" sheet steel kicking around, so here is where I am currently, I cut the mounting tabs off a worn out biopace ring I had kicking round and used some 10 mm washers from the hardware store along with some MTB granny ring spacers to get it all spaced as it is in these pics, but I am spaced a bit far, I can drop the chainring tabs and add another 10mm washer and that will move the granny ring 1mm closer to the middle ring, which will reduce the chance of the chain fitting between the granny ring and the middle ring and should be just about right, or as good as I can hope for. https://i.postimg.cc/zGMGZPVb/841523...E1E54800A4.jpg It doesn't look all that good as 3 holes and 5 holes have inherent asymmetry, but I will be able to line things up better for the final piece. I will paint it black to attempt to hide it behind the chrome rings, and I will definitely apply some drillium to it, https://i.postimg.cc/9f7FWt7x/A21955...8C8CC07582.jpg The reason I have the granny ring space out a bit farther than ideal is due to the mounting bolt for the middle and big rings, here is a pic of the current clearance, I do have an extra mm there, if the chain rubs on the bolt heads slightly I'm not too worried about it as they are domed so the chain won't catch. https://i.postimg.cc/8cDCXJsZ/EF9F20...E2095E8312.jpg As for shifting to the granny ring, my current BB Spindle is pretty beat up, so I'm going to look for one that is a bit longer to put the granny ring a bit further outboard. I also imagine I'll have to modify the front derailleur cage to make it longer to deal with the size difference, 52 big ring 28 granny ring. Lastly, I think this Nervar crank has a 116 BCD, is that correct? Was that standard for all/most of the 3 bolt cranks from this era? Thoughts? |
I can't tell you about the base circle diameters for three pin cranks, but I can tell you that look great. Nice pictures. Thanks for posting. Keep the pictures coming.
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Most inventive! :thumb: "Lastly, I think this Nervar crank has a 116 BCD, is that correct? Was that standard for all/most of the 3 bolt cranks from this era?" yessiree ;) ----- |
One of the inherent joys of this hobby is problem solving, and that looks like a fun endeavor. Kudos!
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It looks like quite an egineering project, very inventive! I may have posted this on your other thread, but I'm very happy with this setup on my '73 SC. Previous owner had installed a Sugino AT crank (no chain rings when found) and cotterless BB. I found 32/40/50t rings for it for $5 each in my LBS back room. The front is shifted very nicely by a Suntour Cyclone II FD, a swap meet find. In back I have a 34t six speed Megarange shifted by a Suntour VGT Luxe, another swap meet find. I don't think I have $100 in the whole drivetrain as shown. I realize that the engineering challenge is part of the fun, but as my first ever build, I went with proven components, that while on the cheap, bolt right on, and play well together. I walked three hills on 2018 Eroica, and may change the inner ring to a 26t, which I also have. The Sugino BCD is 110/74mm, which has a lot of ring choices. Good luck with yours, hope to see you on the ride, riding by, as I walk along. 😉
https://cimg8.ibsrv.net/gimg/bikefor...e6fe75acd8.jpg 50t shown, I now have a 52t big ring. |
Originally Posted by jackbombay
(Post 21277061)
I think this Nervar crank has a 116 BCD, is that correct? Was that standard for all/most of the 3 bolt cranks from this era?
Re: Nervar crank BCD. 116mm was not the only BCD for 3-arm cranks of that period, but it was probably the most common, and included Nervar: http://www.os2.dhs.org/~john/3-arm.jpg Source: Sutherland's 4th Edition |
Very creative, nicely done. The only thing I would do differently would be to try to find a smaller outer ring, such as a 48, to facilitate shifting.
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Originally Posted by Slightspeed
(Post 21277390)
It looks like quite an egineering project, very inventive! I may have posted this on your other thread, but I'm very happy with this setup on my '73 SC. Previous owner had installed a Sugino AT crank (no chain rings when found) and cotterless BB. I found 32/40/50t rings for it for $5 each in my LBS back room. The front is shifted very nicely by a Suntour Cyclone II FD, a swap meet find. In back I have a 34t six speed Megarange shifted by a Suntour VGT Luxe, another swap meet find. I don't think I have $100 in the whole drivetrain as shown. I realize that the engineering challenge is part of the fun, but as my first ever build, I went with proven components, that while on the cheap, bolt right on, and play well together.
I currently have a Suntour VX front derr, I doubt it will play well with the triple, a bit of googling did point to the Cyclone as a viable candidate for three rigs up front, good to hear that it works for you! Will the cage be "tall" enough to have a big ring of 50 and small of 26? Or will you have to keep the rear on the larger cogs for the chain to not drag on the bottom of the front derr cage when you are in the small ring? I'm pretty much expecting that, and it doesn't bother me really, but if it can all come together without chain drag when using the granny ring with cogs other than the big one I'd be quite happy!
Originally Posted by Slightspeed
(Post 21277390)
I walked three hills on 2018 Eroica, and may change the inner ring to a 26t, which I also have. The Sugino BCD is 110/74mm, which has a lot of ring choices. Good luck with yours, hope to see you on the ride, riding by, as I walk along. 😉
Originally Posted by JohnDThompson
(Post 21277421)
Nicely done. Have you ridden with it yet?
I realize I can pick up some 1/8" aluminum sheet from the metal shop when I'm out that way, would be a lot nicer than steel plate and I can polish it so it will sort of match the chrome cranks and rings.
Originally Posted by JohnDThompson
(Post 21277421)
My only concern is if the chain catches on the triplizer mount when shifting between the middle and inner rings.
Originally Posted by JohnDThompson
(Post 21277421)
Re: Nervar crank BCD. 116mm was not the only BCD for 3-arm cranks of that period, but it was probably the most common, and included Nervar:
Originally Posted by John E
(Post 21277485)
Very creative, nicely done. The only thing I would do differently would be to try to find a smaller outer ring, such as a 48, to facilitate shifting.
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I've not actually tried the 26t inner ring with this set up. I have my doubts that it will work without dropping the FD, which would require a smaller big ring. Like you, I like my 52, even if there isn't a lot of road to use it on for Eroica. As an aside, i did run a 52/34 compact double on my Peugeot with a 28t rear. It worked decently with a Shimano Exage FD, but switched it out for a more "French" Stronglight 99 52/40, still keeping the 28t rear. There was some chain sag and it did drag on the FD cage a little small/small with the 52/34. Ive thought of trying this set-up on the SC but with the 34t rear (1:1) lowest gear. The triple does get hung between gears every now and then, mostly operator error, and the compact double eliminates that, hopefully.
https://cimg8.ibsrv.net/gimg/bikefor...242a988cc4.jpg |
I set it all up and spun the cranks, and, it works ok. I did have to leave the fixed cup 2.5mm out of the frame to get the 5 bolts for the granny ring to clear the frame, and the adjustable cup doesn't stick out enough for the lockring to fit on so I can't use a BB spacer with this spindle, but I do need a new spindle anyway as this one is notably pitted.
Next issue, my Suntour VX FD drops the chain effortlessly into the granny ring, but the chain has little desire to climb back onto the middle ring, %50 of the time I had to go to the big ring then back to the middle ring to get the chain to the middle ring. BUT, my tripilizer plate is actually a bit thinner than 1/8" by about .5mm (sorry for mixed units!), so with a tripilizer made from actual 1/8" plate the middle ring will be a bit less guarded by the big ring so the chain will be more willing to get from the granny to the middle ring. I can also move the granny ring closer to the middle ring by at least .5mm, probably a whole mm. One time the chain did get caught up between the granny ring and the middle ring, but I couldn't get that to happen a second time, moving the granny ring closer to the middle ring will deal with that though. Lastly, I can't use the smallest 2 cogs in the granny ring or the chain goes slack AND hits the bottom of the FD cage, but I'm fine with that, with the chain on the middle cog in back it was more willing to climb onto the middle ring from the granny ring than when the chain was on the largest cog in back. And here is what it looks like with 28:28 gearing, https://i.postimg.cc/rFSfHg98/E017D0...6A400A7B84.jpg
Originally Posted by Slightspeed
(Post 21277551)
As an aside, i did run a 52/34 compact double on my Peugeot with a 28t rear.
I going to back burner this project for a few days and see if anything else comes to mind, well, I think that getting the ring spacing dialed in will help it out notably, and I can't deal with that till early/mid next week... |
Originally Posted by jackbombay
(Post 21277061)
It doesn't look all that good as 3 holes and 5 holes have inherent asymmetry,
Not that you want to start over, but if symmetry is the goal, you could make the triplizer to fit 3 of the 6 bolts on a TA Cyclotouriste ring, and cut the extra 3 mounting points off the ring. I did that here: https://cimg5.ibsrv.net/gimg/bikefor...dacbfd4cf7.jpg -Mark |
Originally Posted by bulgie
(Post 21277911)
I disagree on it not looking good. It doesn't look 'factory', but it looks awesome because it calls attention to the fact that it's DIY -- and it's awesome for a DIY effort!
I do like it, but my preferance is for a bit less DIY look, making it out of aluminum and polishing that will be a good blend of home made and "factory" I think, plus it will weigh less!
Originally Posted by bulgie
(Post 21277911)
Not that you want to start over, but if symmetry is the goal, you could make the triplizer to fit 3 of the 6 bolts on a TA Cyclotouriste ring, and cut the extra 3 mounting points off the ring. I did that here:
https://cimg5.ibsrv.net/gimg/bikefor...dacbfd4cf7.jpg -Mark As I already have this 28t ring I'm going to keep tinkering with this, but that is really clean tripilizer set-up! |
Originally Posted by jackbombay
(Post 21278597)
nice set up there! how is the granny ring spaced off the spider?
So the way it is set up now is sort of a mock-up. It uses standard TA Triple chainring bolts, where the "nut" (female threaded part) is extra-long. There's a stack of TA chainring spacers between the spider and the granny. https://cimg4.ibsrv.net/gimg/bikefor...99eac04eef.jpg A stack of spacers is not as good as one single spacer in the right width, so I would make those if this crank were actually going to be ridden. Making custom-length aluminum spacers is one of the easiest jobs there is, for someone with a lathe. I don't have a lathe anymore myself, but I know people who do, whom I could ask for a favor. I would probably want to use something other than TA brand bolts because they kinda suck. I mean yeah there are cranks out there with 1940s vintage TA bolts that are still going strong. So I'm not saying they aren't up to the job, but still they're kinda weak. And there's only 3 bolts here, where TA intended you to use 6. Making custom bolts from scratch is definitely way beyond my current capabilities -- broaching the allen-wrench sockets for example. But it may be possible to find some existing bolt that could be pressed into service. The only problem is that unusual hole size in TA chainrings, which limits choices. Mark B |
Looks like you could increase the OD of the spacers as well if you were to make your own which would result in less tension on the bolts when power was applied to the crank.
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I did get some aluminum to make this out of, I told the metal shop, 1/8" thick, when I picked it up it seems thinner than that, the guy told me he didn't know if it was 1/8" but it was .125" thick, this thing is, he wasn't joking, but he was also wrong as it turns out it was 3/64, but I was able to make it work with various washers, this does place the middle ring .5mm further away from the big ring that it is in stock form, which helps ever so slightly to get the chain from the granny ring to the middle ring.
I did get a slightly longer BB spindle from ebay, $20, free shipping from the UK, it doesn't seem to be particularly high quality, but there isn't much choice for cottered BB spindles out there. I did have to grind away a tiny bit of the BB lug that holds the drive side chain stay to get clearance for the mounting bolts for the granny ring. As of now this works decently in the bike stand, it drops into the granny ring well, but I did have to mount the front derailleur ever so slightly twisted for that to happen, and it usually comes back up from the granny ring to the middle ring decently, but sometimes it isn't all that willing to do so. I really just need to ride it at this point to test it out further. https://i.postimg.cc/wjXH939s/C95A50...2899577E76.jpg |
22T freewheel cog bolted to a Maxy II spider, plus a 34T and a 45T. This combo shifts pretty easily. It's fun doing this stuff, but cottered steel would be tougher to do right.
https://cimg4.ibsrv.net/gimg/bikefor...8ab9c629e4.jpg |
Originally Posted by thumpism
(Post 21315968)
22T freewheel cog bolted to a Maxy II spider, plus a 34T and a 45T. This combo shifts pretty easily. It's fun doing this stuff, but cottered steel would be tougher to do right.
I think I have this set up well enough, I may end up drilling and tapping the middle ring and running some short screws through from the outside of the ring to give the chain some pegs to grab onto to climb out of the granny ring better like so many modern rings have, but I need to ride it first before messing with that. This cottered crank was actually about as good as a guy could hope for for this modification as the middle/big ring spacers could just get replaced with the tripilizer. |
This might seem like a really dumb question, but i've never been to Eroica. My apologies in advance. From my understanding, they're big about only allowing "period-correct" bicycles ride. Would such a modification violate the rules/spirit of the event?
Some possible solutions for your predicaments: Have you checked the chainline of the crankset with your modification? Maybe your setup is correct, and it's the chainline that's wrong. An "alpine" front derailleur would probably solve your slack chain issue. When your chain goes slack and hits the cage on the highest two cogs in the granny, you're probably exceeding the chain wrap capacity of the rear derailleur. Do you have a suntour mountech, or a campagnolo RD with soma's new cage plates? |
Originally Posted by smoothness
(Post 21316006)
This might seem like a really dumb question, but i've never been to Eroica. My apologies in advance. From my understanding, they're big about only allowing "period-correct" bicycles ride. Would such a modification violate the rules/spirit of the event?
But they allow brand new bikes with 10 speed cassette rear ends in the vintage bike ride too, so I'm not going to lose any sleep over showing up with a granny ring set-up that I could have easily built before 1987. https://www.bicycling.com/bikes-gear...nchi-l-eroica/ |
Originally Posted by smoothness
(Post 21316006)
This might seem like a really dumb question, but i've never been to Eroica. My apologies in advance. From my understanding, they're big about only allowing "period-correct" bicycles ride. Would such a modification violate the rules/spirit of the event?
Some possible solutions for your predicaments: Have you checked the chainline of the crankset with your modification? Maybe your setup is correct, and it's the chainline that's wrong. An "alpine" front derailleur would probably solve your slack chain issue. When your chain goes slack and hits the cage on the highest two cogs in the granny, you're probably exceeding the chain wrap capacity of the rear derailleur. Do you have a suntour mountech, or a campagnolo RD with soma's new cage plates? This is the embodiment of Eroica, plain, simple and effective, no slight of hand, no fancy cnc plasma, lazer nonsense, just good old fashion ingenuity. Way back at the start of the whole thing, necessity was always the mother of invention, everything from cocaine to bailing wire was employed liberally and often with great results just like this that we still benefit from to this day. This is fantastic work. :thumb: |
Originally Posted by jackbombay
(Post 21277615)
I set it all up and spun the cranks, and, it works ok. I did have to leave the fixed cup 2.5mm out of the frame to get the 5 bolts for the granny ring to clear the frame, and the adjustable cup doesn't stick out enough for the lockring to fit on so I can't use a BB spacer with this spindle, but I do need a new spindle anyway as this one is notably pitted.
Next issue, my Suntour VX FD drops the chain effortlessly into the granny ring, but the chain has little desire to climb back onto the middle ring, %50 of the time I had to go to the big ring then back to the middle ring to get the chain to the middle ring. BUT, my tripilizer plate is actually a bit thinner than 1/8" by about .5mm (sorry for mixed units!), so with a tripilizer made from actual 1/8" plate the middle ring will be a bit less guarded by the big ring so the chain will be more willing to get from the granny to the middle ring. I can also move the granny ring closer to the middle ring by at least .5mm, probably a whole mm. One time the chain did get caught up between the granny ring and the middle ring, but I couldn't get that to happen a second time, moving the granny ring closer to the middle ring will deal with that though. Lastly, I can't use the smallest 2 cogs in the granny ring or the chain goes slack AND hits the bottom of the FD cage, but I'm fine with that, with the chain on the middle cog in back it was more willing to climb onto the middle ring from the granny ring than when the chain was on the largest cog in back. And here is what it looks like with 28:28 gearing, https://i.postimg.cc/rFSfHg98/E017D0...6A400A7B84.jpg Going compact double has certainly crossed my mind as well, if I went to a 6 speed freewheel with a 34 I could still get close to 1:1 that way, well, I'm not sure what the smallest 116 BCD ring is, maybe a 36? so I'd have 36:34. There really are not any rings around in the 3 bolt 116 BCD pattern, I'm not opposed to making one out of steel plate, but I'd probably be back in the same boat of mediocre shifting up front with 52/36 where the front shifting is currently quite crisp and enjoyable between the 40 and 52. I going to back burner this project for a few days and see if anything else comes to mind, well, I think that getting the ring spacing dialed in will help it out notably, and I can't deal with that till early/mid next week... Your solution is interesting. Up to you how to get it done. The chainrings do exist. If you did use an all vintage double would recommend insisting on NOS only and make it a 48/36 or even a 46/36. |
Originally Posted by jackbombay
(Post 21315770)
I did get some aluminum to make this out of, I told the metal shop, 1/8" thick, when I picked it up it seems thinner than that, the guy told me he didn't know if it was 1/8" but it was .125" thick, this thing is, he wasn't joking, but he was also wrong as it turns out it was 3/64, but I was able to make it work with various washers, this does place the middle ring .5mm further away from the big ring that it is in stock form, which helps ever so slightly to get the chain from the granny ring to the middle ring.
I did get a slightly longer BB spindle from ebay, $20, free shipping from the UK, it doesn't seem to be particularly high quality, but there isn't much choice for cottered BB spindles out there. I did have to grind away a tiny bit of the BB lug that holds the drive side chain stay to get clearance for the mounting bolts for the granny ring. As of now this works decently in the bike stand, it drops into the granny ring well, but I did have to mount the front derailleur ever so slightly twisted for that to happen, and it usually comes back up from the granny ring to the middle ring decently, but sometimes it isn't all that willing to do so. I really just need to ride it at this point to test it out further. https://i.postimg.cc/wjXH939s/C95A50...2899577E76.jpg Neat project. |
Originally Posted by merziac
(Post 21316060)
They wouldn't have a leg to stand on, any and all modifications using original or period correct like components would have to be met with no less than the utmost enthusiasm, to do otherwise would be absolute foolishness.
This is the embodiment of Eroica, plain, simple and effective, no slight of hand, no fancy cnc plasma, lazer nonsense, just good old fashion ingenuity. Way back at the start of the whole thing, necessity was always the mother of invention, everything from cocaine to bailing wire was employed liberally and often with great results just like this that we still benefit from to this day. This is fantastic work. :thumb:
Originally Posted by 63rickert
(Post 21316297)
If you did use an all vintage double would recommend insisting on NOS only and make it a 48/36 or even a 46/36.
Originally Posted by BFisher
(Post 21316365)
Don't know if this would help, and you may have tried this already, but it looks like that derailleur could come down a few millimeters.
Neat project. Winter storm warning here for the next 3 days, so zero chance of actually riding the bike soon. |
This is all finished up, waiting for road trials, I softened the edges and put some polish on it so it will match the chrome rings, man this looks good! ;-)
https://i.postimg.cc/mrdzFrWX/F564CC...22AECB6CFB.jpg https://i.postimg.cc/Jh7HnkvH/8-AB81...164-FFF4-E.jpg https://i.postimg.cc/RFyWXbFw/039114...C370CDB5AB.jpg And I know I'm preaching to the choir here, but is there any chance at all that a modern drive train will look this good when its 48 years old? I only gave the chrome socks the slightest buff with steel wool and they look so nice! Some neverdul chrome polish will make them look even better! https://i.postimg.cc/63y7VN99/3F5F69...E05D0B195A.jpg |
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