Go Back  Bike Forums > Bike Forums > Classic & Vintage
Reload this Page >

Ever modified a crank to add a granny?

Notices
Classic & Vintage This forum is to discuss the many aspects of classic and vintage bicycles, including musclebikes, lightweights, middleweights, hi-wheelers, bone-shakers, safety bikes and much more.

Ever modified a crank to add a granny?

Old 08-24-19, 10:12 AM
  #1  
thook
(rhymes with spook)
Thread Starter
 
thook's Avatar
 
Join Date: Aug 2009
Location: Winslow, AR
Posts: 2,795

Bikes: '83 univega gran turismo x2, '85 schwinn super le tour,'89 miyata triple cross, '91 GT tequesta, '90 yokota grizzly peak, '94 GT backwoods, '95'ish scott tampico, '98 bonty privateer, '93 mongoose crossway 625, '98 parkpre ariel, 2k'ish giant fcr3

Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 919 Post(s)
Liked 745 Times in 546 Posts
Ever modified a crank to add a granny?

member merziac posted some pics of his merz mtb with a modified dura ace crank making it a triple. seems like a neat idea. certainly looks nice! but, it got me to thinkin'

i've got two early 80's SR super custom cranksets with a 118bcd and the smallest ring you can run is 36t. even with a larger cog of 34t, that's still not real low for big hills around here. so, since i have two, it occurred to me i could try modifying the spider of one to fit a 74bcd inner to make a triple

i have a drill press, tapping tools, good bits, a vice, metric measuring tools, ring spacers and bolts.....basically everything i would think i'd need to try it. thing is, i believe there's a probably a good efficient way to go about doing this since it's obviously been done. no need to reinvent, and i could hopefully avoid mistakes. for example, what's an effective way to secure the part and make sure the holes are drilled evenly/straight and properly centered? and, of course, if there's design considerations of the part that might lead to failure, i'll have to reconsider this attempt

as always, thanks!!!

ps. i know...it'd be much easier to use a same period triple crank to achieve desired gearing, and for now i'm doing that. but, it think it'd be swell to run the original SR. i've got several 118 rings for it, too
thook is offline  
Old 08-24-19, 11:26 AM
  #2  
The Golden Boy 
Extraordinary Magnitude
 
The Golden Boy's Avatar
 
Join Date: Aug 2009
Location: Waukesha WI
Posts: 13,640

Bikes: 1978 Trek TX700; 1978/79 Trek 736; 1984 Specialized Stumpjumper Sport; 1984 Schwinn Voyageur SP; 1985 Trek 620; 1985 Trek 720; 1986 Trek 400 Elance; 1987 Schwinn High Sierra; 1990 Miyata 1000LT

Mentioned: 84 Post(s)
Tagged: 0 Thread(s)
Quoted: 2597 Post(s)
Liked 1,678 Times in 926 Posts
I wouldn't "try" this out on a crank I wanted or valued. I'd do it (practice) on something else-

Then again- I wouldn't do this to a crank- first- I don't know what I'm doing. Second- I don't know how much tolerance the alloy has- even if all the drilling is perfect- I think the Super Custom lived at the lower end of the SR range and I don't know what that means as far as metallurgy and forging and quality. Third- I don't know if by drilling you're introducing cracks or stress risers that could fail catastrophically and suddenly.

SR made a Super Custom triple with an 86 BCD- I had one on my Trek 420. It's the same BCD as the Stronglight 99 crankset.
__________________
*Recipient of the 2006 Time Magazine "Person Of The Year" Award*

Commence to jigglin’ huh?!?!

"But hey, always love to hear from opinionated amateurs." -says some guy to Mr. Marshall.
The Golden Boy is offline  
Old 08-24-19, 12:43 PM
  #3  
droppedandlost 
small ring
 
droppedandlost's Avatar
 
Join Date: Jul 2012
Location: PNW
Posts: 1,030
Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 437 Post(s)
Liked 925 Times in 370 Posts
You also need high angle drill bits. Aluminum is soft and will tear rather than chipping as you drill.
__________________
72 Bob Jackson -- 74 Motobecane Grand Jubile -- 74 Sekine SHS 271 -- 80 Nishiki International
85 Shogun 800 -- 86 Tommasini Super Prestige -- 92 Specialized Rockhopper -- 17 Colnago Arabesque
droppedandlost is offline  
Old 08-24-19, 01:43 PM
  #4  
merziac
Senior Member
 
merziac's Avatar
 
Join Date: Oct 2015
Location: PDX
Posts: 14,099

Bikes: Merz x 5 + Specialized Merz Allez x 2, Strawberry/Newlands/DiNucci/Ti x3, Gordon, Fuso/Moulton x2, Bornstein, Paisley,1958-74 Paramounts x3, 3rensho, 74 Moto TC, 73-78 Raleigh Pro's x5, Marinoni x2, 1960 Cinelli SC, 1980 Bianchi SC, PX-10 X 2

Mentioned: 267 Post(s)
Tagged: 0 Thread(s)
Quoted: 4493 Post(s)
Liked 6,297 Times in 3,632 Posts
Originally Posted by thook
member merziac posted some pics of his merz mtb with a modified dura ace crank making it a triple. seems like a neat idea. certainly looks nice! but, it got me to thinkin'

i've got two early 80's SR super custom cranksets with a 118bcd and the smallest ring you can run is 36t. even with a larger cog of 34t, that's still not real low for big hills around here. so, since i have two, it occurred to me i could try modifying the spider of one to fit a 74bcd inner to make a triple

i have a drill press, tapping tools, good bits, a vice, metric measuring tools, ring spacers and bolts.....basically everything i would think i'd need to try it. thing is, i believe there's a probably a good efficient way to go about doing this since it's obviously been done. no need to reinvent, and i could hopefully avoid mistakes. for example, what's an effective way to secure the part and make sure the holes are drilled evenly/straight and properly centered? and, of course, if there's design considerations of the part that might lead to failure, i'll have to reconsider this attempt

as always, thanks!!!

ps. i know...it'd be much easier to use a same period triple crank to achieve desired gearing, and for now i'm doing that. but, it think it'd be swell to run the original SR. i've got several 118 rings for it, too
The guys who do this are master craftsmen, Merz being at the top of the list, he did all of his own and may still. I'm no expert but I think its done on a milling machine or drill press with a rotating table so they are done in a perfect circle. I have seen it done by one offs but they were expert machinists to begin with. I have always thought you could use a BB setup of some sort on a press for the rotational portion, if you could get it clamped down solid and square it would be a matter of drilling the holes right in the middle of the arms.
merziac is offline  
Old 08-24-19, 03:14 PM
  #5  
Depaso
Member
 
Join Date: Jul 2015
Posts: 33
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 14 Post(s)
Liked 4 Times in 3 Posts
Campagnolo drilled by hand using the plate as a template. DA same result with tripleizer plate

Depaso is offline  
Likes For Depaso:
Old 08-24-19, 03:58 PM
  #6  
thook
(rhymes with spook)
Thread Starter
 
thook's Avatar
 
Join Date: Aug 2009
Location: Winslow, AR
Posts: 2,795

Bikes: '83 univega gran turismo x2, '85 schwinn super le tour,'89 miyata triple cross, '91 GT tequesta, '90 yokota grizzly peak, '94 GT backwoods, '95'ish scott tampico, '98 bonty privateer, '93 mongoose crossway 625, '98 parkpre ariel, 2k'ish giant fcr3

Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 919 Post(s)
Liked 745 Times in 546 Posts
Originally Posted by Depaso
Campagnolo drilled by hand using the plate as a template. DA same result with tripleizer plate
using the plate? you mean the chainring? how'd you center around the spindle taper?

Last edited by thook; 08-24-19 at 05:35 PM.
thook is offline  
Old 08-24-19, 05:14 PM
  #7  
52telecaster
ambulatory senior
 
52telecaster's Avatar
 
Join Date: Dec 2016
Location: Peoria Il
Posts: 6,347

Bikes: Austro Daimler modified by Gugie! Raleigh Professional and lots of other bikes.

Mentioned: 76 Post(s)
Tagged: 0 Thread(s)
Quoted: 1953 Post(s)
Liked 3,633 Times in 1,670 Posts
Triplizers are great, in lew of that id want an indexing head and a drill press minimum.
52telecaster is offline  
Old 08-24-19, 05:28 PM
  #8  
thook
(rhymes with spook)
Thread Starter
 
thook's Avatar
 
Join Date: Aug 2009
Location: Winslow, AR
Posts: 2,795

Bikes: '83 univega gran turismo x2, '85 schwinn super le tour,'89 miyata triple cross, '91 GT tequesta, '90 yokota grizzly peak, '94 GT backwoods, '95'ish scott tampico, '98 bonty privateer, '93 mongoose crossway 625, '98 parkpre ariel, 2k'ish giant fcr3

Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 919 Post(s)
Liked 745 Times in 546 Posts
Originally Posted by The Golden Boy
I wouldn't "try" this out on a crank I wanted or valued. I'd do it (practice) on something else-

Then again- I wouldn't do this to a crank- first- I don't know what I'm doing. Second- I don't know how much tolerance the alloy has- even if all the drilling is perfect- I think the Super Custom lived at the lower end of the SR range and I don't know what that means as far as metallurgy and forging and quality. Third- I don't know if by drilling you're introducing cracks or stress risers that could fail catastrophically and suddenly.

SR made a Super Custom triple with an 86 BCD- I had one on my Trek 420. It's the same BCD as the Stronglight 99 crankset.
i'm confident with my skill level. i've done enough drilling and tapping on engines and many other things. i'm just looking for procedural input. but, thank you for your concerns

lower end? i wouldn't say that at all! a lot of really high quality bikes came out with them. as well, it's a high quality alloy when you do some reading on them. super nice cranks, i think. polished up they resemble any of the "echelon" components of the day. it's just too bad they had this funky bcd...lol
i have considered finding an 86 bcd and it'd be convenient, but 28t is the smallest ring you can use. plus, i have this thing about trying to use what i have
thook is offline  
Old 08-24-19, 05:35 PM
  #9  
thook
(rhymes with spook)
Thread Starter
 
thook's Avatar
 
Join Date: Aug 2009
Location: Winslow, AR
Posts: 2,795

Bikes: '83 univega gran turismo x2, '85 schwinn super le tour,'89 miyata triple cross, '91 GT tequesta, '90 yokota grizzly peak, '94 GT backwoods, '95'ish scott tampico, '98 bonty privateer, '93 mongoose crossway 625, '98 parkpre ariel, 2k'ish giant fcr3

Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 919 Post(s)
Liked 745 Times in 546 Posts
Originally Posted by 52telecaster
Triplizers are great, in lew of that id want an indexing head and a drill press minimum.
indexing head?

i'm pondering making a (hand)drill guide using a sacrificial crank with existing 74bcd pattern. secure the two together at the spindle and pedal locations and drill through one into the other using the 74bcd holes to guide my bit. when drilling/tapping/installing inserts, the existing holes with buggered threads already act as guides in many cases. you just have to be patient and drill slow so you don't move off center. then you can rethread and/or install inserts, etc.
thook is offline  
Old 08-24-19, 05:59 PM
  #10  
old's'cool
curmudgineer
 
old's'cool's Avatar
 
Join Date: Dec 2009
Location: Chicago SW burbs
Posts: 4,429

Bikes: 2 many 2 fit here

Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 263 Post(s)
Liked 111 Times in 70 Posts
Originally Posted by 52telecaster
Triplizers are great, in lew of that id want an indexing head and a drill press minimum.
Indeed. Only a knowledgeable machinist understands what is entailed to get a good result with high probability. Then there is the question of whether there is sufficient meat in the spider to allow the required material removal while preserving adequate strength.
old's'cool is offline  
Old 08-24-19, 06:01 PM
  #11  
Manny66 
Senior Member
 
Manny66's Avatar
 
Join Date: Oct 2018
Location: Whittier
Posts: 862

Bikes: 1973 Colnago Super, Litespeed Classic , Automoto , Pinarello Gavia TSX,Eddy Merckx Corsa Extra,Eddy Merckx EMX-5 , 1982 Moser SL, Concorde TSX, Vitus 979 KAS. Diamant SLX,60's Meteor

Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 233 Post(s)
Liked 922 Times in 318 Posts
DO IT!!

Drilling and tapping an old aluminum crank is a piece of cake. If you screw it up or dont like it toss it in the junk drawer and try again.

You seem proficient on engine blocks and already have the tools so get out a 6inch scale, measure twice drill once and go for it. The issue would be frame clearance so a longer BB spindle would be definitely be needed.
Manny66 is offline  
Likes For Manny66:
Old 08-24-19, 06:15 PM
  #12  
noglider 
aka Tom Reingold
 
noglider's Avatar
 
Join Date: Jan 2009
Location: New York, NY, and High Falls, NY, USA
Posts: 40,691

Bikes: 1962 Rudge Sports, 1971 Raleigh Super Course, 1971 Raleigh Pro Track, 1974 Raleigh International, 1975 Viscount Fixie, 1982 McLean, 1996 Lemond (Ti), 2002 Burley Zydeco tandem

Mentioned: 510 Post(s)
Tagged: 0 Thread(s)
Quoted: 7287 Post(s)
Liked 2,362 Times in 1,381 Posts
@jonwvara does this. Jon, want to talk about it here?
__________________
Tom Reingold, tom@noglider.com
New York City and High Falls, NY
Blogs: The Experienced Cyclist; noglider's ride blog

“When man invented the bicycle he reached the peak of his attainments.” — Elizabeth West, US author

Please email me rather than PM'ing me. Thanks.
noglider is offline  
Old 08-24-19, 09:52 PM
  #13  
scarlson 
Senior Member
 
scarlson's Avatar
 
Join Date: Jun 2010
Location: Medford MA
Posts: 2,089

Bikes: Ron Cooper touring, 1959 Jack Taylor 650b ladyback touring tandem, Vitus 979, Joe Bell painted Claud Butler Dalesman, Colin Laing curved tube tandem, heavily-Dilberted 1982 Trek 6xx, René Herse tandem

Mentioned: 80 Post(s)
Tagged: 0 Thread(s)
Quoted: 963 Post(s)
Liked 1,447 Times in 721 Posts
You also need high angle drill bits. Aluminum is soft and will tear rather than chipping as you drill.
I've always machined aluminum with normal drill bits and tooling, whether it's castings, tubing, weird alloys, you name it. Nothing special in my machining experience, and I get beautiful chips. Use some cutting oil and change your feeds/speeds if you're shredding it. I like the way Tap Magic Aluminum works, but I hate the way it smells, especially when I smoke it up, parting things on the lathe on a taper. WD40 or 10W40 or even Pro Link wet chain lube or Fluid Film is also fine. Basically anything is better than nothing for most things. Then stainless and inconel often do better without cutting fluid as long as you don't let your tooling dwell and your workpiece harden, but I digress.

The derailleur will take up any out-of-round you introduce, and it's a granny gear, it's not like you're going to spend a ton of time in it. I would just go for it. I would rest the chainring bolt flats of the crank on some blocks to make sure it's parallel with the face of the crank. Depending on your drill press table, you may be able to stick an appropriate sized bolt up through the table and put that through the square tapered hole so that you can put all the holes the same distance from the center. Using the chainring as a template is also a good idea. I'd bolt it down to the first hole you drill/tap and then each consecutive hole. Do them in a cross pattern, probably. If the surface you're entering is at an angle, it may benefit you to buy a 1/4" or 5/16" flat endmill to throw in your drill press chuck and touch to the face you're drilling to make it flat so that the drill doesn't try to move as it's entering an angled face. Plunging an endmill should not be a problem for your drill press chuck, despite what others may tell you.

Oh, and you know about the trick to use a tap guide in the chuck of your drill press to align the tap and provide a little pressure, right? It requires your work to be held down to your drill press table, but it makes tapping a lot easier. Just don't move anything after you have drilled the hole, chuck the tap guide in your drill press, and pilot the tap with it.

Now that I have access to the tools, yeah, I'd program a mill to CNC drill it. Because I can. But if you have a good eye, you'll be surprised how close you can get with normal tools.
scarlson is offline  
Likes For scarlson:
Old 08-24-19, 11:01 PM
  #14  
thook
(rhymes with spook)
Thread Starter
 
thook's Avatar
 
Join Date: Aug 2009
Location: Winslow, AR
Posts: 2,795

Bikes: '83 univega gran turismo x2, '85 schwinn super le tour,'89 miyata triple cross, '91 GT tequesta, '90 yokota grizzly peak, '94 GT backwoods, '95'ish scott tampico, '98 bonty privateer, '93 mongoose crossway 625, '98 parkpre ariel, 2k'ish giant fcr3

Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 919 Post(s)
Liked 745 Times in 546 Posts
and @52telecaster i've never used an indexing head in anything i've done, but i think needing one here might be unnecessary

Originally Posted by old's'cool
Indeed. Only a knowledgeable machinist understands what is entailed to get a good result with high probability. Then there is the question of whether there is sufficient meat in the spider to allow the required material removal while preserving adequate strength.
i understand.... the crank and targeted spots for drilling would need to be flush to a horizontal surface (drill table) to be made plum to the vertical plane of the drill travel. i've come up with a couple of ways in my head to maybe be able to do that. it's a little involved and i'd have to experiment certainly with like a scrap disk of some sort to make sure i get distance and planar relationships accurate enough. tomorrow, when i have a little more time, i'll try to explain. not too complicated, but i haven't worked out all details, either. essentially, though, the crank would become it's own indexing head utilizing a bottom bracket installed into a shell cut from a scrap from and secured to some plate metal acting as a the table.
thook is offline  
Old 08-24-19, 11:03 PM
  #15  
thook
(rhymes with spook)
Thread Starter
 
thook's Avatar
 
Join Date: Aug 2009
Location: Winslow, AR
Posts: 2,795

Bikes: '83 univega gran turismo x2, '85 schwinn super le tour,'89 miyata triple cross, '91 GT tequesta, '90 yokota grizzly peak, '94 GT backwoods, '95'ish scott tampico, '98 bonty privateer, '93 mongoose crossway 625, '98 parkpre ariel, 2k'ish giant fcr3

Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 919 Post(s)
Liked 745 Times in 546 Posts
Originally Posted by Manny66
DO IT!!

Drilling and tapping an old aluminum crank is a piece of cake. If you screw it up or dont like it toss it in the junk drawer and try again.

You seem proficient on engine blocks and already have the tools so get out a 6inch scale, measure twice drill once and go for it. The issue would be frame clearance so a longer BB spindle would be definitely be needed.
i like your style...lol!! thanks for the encouragement

oh, the longer spindle is already there on the bike. and, the crankset on it is already a triple at 52/47/36. take the other (identical) spider i have, modify, and swap. easy. not sure on how i'll gear....either half step with granny or just basic crossover. likely/ultimately a half step, though, if i can find a 46t ring with the 118bcd. there's one on ebay right now, but it's out of the uk and shipping is reflective. so, it may start it's new modified life with 47/36/24 rings

Last edited by thook; 08-24-19 at 11:26 PM.
thook is offline  
Old 08-24-19, 11:13 PM
  #16  
thook
(rhymes with spook)
Thread Starter
 
thook's Avatar
 
Join Date: Aug 2009
Location: Winslow, AR
Posts: 2,795

Bikes: '83 univega gran turismo x2, '85 schwinn super le tour,'89 miyata triple cross, '91 GT tequesta, '90 yokota grizzly peak, '94 GT backwoods, '95'ish scott tampico, '98 bonty privateer, '93 mongoose crossway 625, '98 parkpre ariel, 2k'ish giant fcr3

Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 919 Post(s)
Liked 745 Times in 546 Posts
Originally Posted by scarlson
I've always machined aluminum with normal drill bits and tooling, whether it's castings, tubing, weird alloys, you name it. Nothing special in my machining experience, and I get beautiful chips. Use some cutting oil and change your feeds/speeds if you're shredding it. I like the way Tap Magic Aluminum works, but I hate the way it smells, especially when I smoke it up, parting things on the lathe on a taper. WD40 or 10W40 or even Pro Link wet chain lube or Fluid Film is also fine. Basically anything is better than nothing for most things. Then stainless and inconel often do better without cutting fluid as long as you don't let your tooling dwell and your workpiece harden, but I digress.

The derailleur will take up any out-of-round you introduce, and it's a granny gear, it's not like you're going to spend a ton of time in it. I would just go for it. I would rest the chainring bolt flats of the crank on some blocks to make sure it's parallel with the face of the crank. Depending on your drill press table, you may be able to stick an appropriate sized bolt up through the table and put that through the square tapered hole so that you can put all the holes the same distance from the center. Using the chainring as a template is also a good idea. I'd bolt it down to the first hole you drill/tap and then each consecutive hole. Do them in a cross pattern, probably. If the surface you're entering is at an angle, it may benefit you to buy a 1/4" or 5/16" flat endmill to throw in your drill press chuck and touch to the face you're drilling to make it flat so that the drill doesn't try to move as it's entering an angled face. Plunging an endmill should not be a problem for your drill press chuck, despite what others may tell you.

Oh, and you know about the trick to use a tap guide in the chuck of your drill press to align the tap and provide a little pressure, right? It requires your work to be held down to your drill press table, but it makes tapping a lot easier. Just don't move anything after you have drilled the hole, chuck the tap guide in your drill press, and pilot the tap with it.

Now that I have access to the tools, yeah, I'd program a mill to CNC drill it. Because I can. But if you have a good eye, you'll be surprised how close you can get with normal tools.
i'll have to read this a couple times over tomorrow for it totally sink in, but i will and then reply. thank you much for quite the input!
thook is offline  
Likes For thook:
Old 08-24-19, 11:36 PM
  #17  
dabac
Senior Member
 
Join Date: Mar 2008
Posts: 8,688
Mentioned: 46 Post(s)
Tagged: 0 Thread(s)
Quoted: 1074 Post(s)
Liked 295 Times in 222 Posts
Originally Posted by scarlson

The derailleur will take up any out-of-round you introduce....
+1
Remember Bio-Pace, anyone?
I’d be more concerned with getting the holes to line up with the holes in the chainring.
I’d definitely want to use a chainring as a guide/template, one way or another. If parts are difficult to clamp, I might do one first, get that screwed in. then make myself a center punch. Or a centering sleeve to a drill. Then do an opposite hole and get that screwed in. Then do the rest.
dabac is offline  
Old 08-25-19, 02:09 AM
  #18  
non-fixie 
Shifting is fun!
 
non-fixie's Avatar
 
Join Date: Aug 2009
Location: South Holland, NL
Posts: 11,001

Bikes: Yes, please.

Mentioned: 277 Post(s)
Tagged: 0 Thread(s)
Quoted: 2182 Post(s)
Liked 4,525 Times in 1,743 Posts
Ever modified a crank to add a granny?

I haven't, but the previous owner of these two has:



__________________
Are we having fun, or what ...



non-fixie is offline  
Likes For non-fixie:
Old 08-25-19, 02:32 AM
  #19  
Depaso
Member
 
Join Date: Jul 2015
Posts: 33
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 14 Post(s)
Liked 4 Times in 3 Posts
Originally Posted by thook
using the plate? you mean the chainring? how'd you center around the spindle taper?
Yes. Chainring. Blame mine and the translator. Sorry, i do not speak English. If you try, the appropriate screws and spacers for the third chainring, are these:


https://www.xxcycle.fr/visserie-pour...-mygal,,fr.php
Depaso is offline  
Old 08-25-19, 02:43 AM
  #20  
Andy_K 
Senior Member
 
Andy_K's Avatar
 
Join Date: Jan 2008
Location: Beaverton, OR
Posts: 14,787

Bikes: Yes

Mentioned: 522 Post(s)
Tagged: 0 Thread(s)
Quoted: 3228 Post(s)
Liked 3,853 Times in 1,436 Posts
Originally Posted by noglider
@jonwvara does this. Jon, want to talk about it here?
What he does isn't what's described here, but it is a much better alternative IMO. Jon makes middle chainrings in 144 and 122 BCD that are customized to allow an inner ring to be bolted to them. No drilling, no permanent modification to the original crank.

I didn't have a good photo of my triplized crank, but here's one I cropped out of a full bike shot.

__________________
My Bikes
Andy_K is online now  
Old 08-25-19, 06:30 AM
  #21  
JohnDThompson 
Old fart
 
JohnDThompson's Avatar
 
Join Date: Nov 2004
Location: Appleton WI
Posts: 24,935

Bikes: Several, mostly not name brands.

Mentioned: 153 Post(s)
Tagged: 0 Thread(s)
Quoted: 3571 Post(s)
Liked 3,367 Times in 1,916 Posts
As others have noted above, a triplizer chainring is a quick, easy, and fully reversible means of adding a "granny" gear to a vintage crank. Red Clover makes a couple versions, the 144mm BCD ring @andy k shows above, and a 122mm BCD version for the Stronglight 93 crank:



JohnDThompson is offline  
Old 08-25-19, 01:31 PM
  #22  
thook
(rhymes with spook)
Thread Starter
 
thook's Avatar
 
Join Date: Aug 2009
Location: Winslow, AR
Posts: 2,795

Bikes: '83 univega gran turismo x2, '85 schwinn super le tour,'89 miyata triple cross, '91 GT tequesta, '90 yokota grizzly peak, '94 GT backwoods, '95'ish scott tampico, '98 bonty privateer, '93 mongoose crossway 625, '98 parkpre ariel, 2k'ish giant fcr3

Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 919 Post(s)
Liked 745 Times in 546 Posts
Originally Posted by Depaso
Yes. Chainring. Blame mine and the translator. Sorry, i do not speak English. If you try, the appropriate screws and spacers for the third chainring, are these:


https://www.xxcycle.fr/visserie-pour...-mygal,,fr.php
no need to apologize, man. i appreciate your input. and, that hardware is a nice option. i'm thinking i want to use studs with some epoxy thread lock, though. even if i have to make some. i can change out rings at whim if i wanted without disturbing threads and hardware in the spider. if i ever cross threaded the spider, i'd be pretty sore about it

so, how'd you center the "plate" on the spider?
thook is offline  
Old 08-25-19, 01:39 PM
  #23  
thook
(rhymes with spook)
Thread Starter
 
thook's Avatar
 
Join Date: Aug 2009
Location: Winslow, AR
Posts: 2,795

Bikes: '83 univega gran turismo x2, '85 schwinn super le tour,'89 miyata triple cross, '91 GT tequesta, '90 yokota grizzly peak, '94 GT backwoods, '95'ish scott tampico, '98 bonty privateer, '93 mongoose crossway 625, '98 parkpre ariel, 2k'ish giant fcr3

Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 919 Post(s)
Liked 745 Times in 546 Posts
Originally Posted by non-fixie



holy shorts!! i have a suntour road vx crank that's just like that. for years i've pondered making it a triple in that exact same manner! i am thrilled to see someone else has actually done it. now you know i'm gonna have to...lol! (at some point, anyway )

thanks so much for sharing!
thook is offline  
Likes For thook:
Old 08-25-19, 01:54 PM
  #24  
jonwvara 
Senior Member
 
jonwvara's Avatar
 
Join Date: Apr 2006
Location: Washington County, Vermont, USA
Posts: 3,787

Bikes: 1966 Dawes Double Blue, 1976 Raleigh Gran Sport, 1975 Raleigh Sprite 27, 1980 Univega Viva Sport, 1971 Gitane Tour de France, 1984 Lotus Classique, 1976 Motobecane Grand Record

Mentioned: 77 Post(s)
Tagged: 0 Thread(s)
Quoted: 758 Post(s)
Liked 647 Times in 343 Posts
Originally Posted by JohnDThompson
As others have noted above, a triplizer chainring is a quick, easy, and fully reversible means of adding a "granny" gear to a vintage crank. Red Clover makes a couple versions, the 144mm BCD ring @andy k shows above, and a 122mm BCD version for the Stronglight 93 crank:



True, I do make the triplizers mentioned above. I also make a 37-tooth 122 BCD ring, which is the smallest tooth count that really works with 122 BCD. They're nice--I use them myself. Go ahead and buy one, somebody--brighten an old man's day.
__________________
www.redclovercomponents.com

"Progress might have been all right once, but it has gone on too long."
--Ogden Nash
jonwvara is offline  
Likes For jonwvara:
Old 08-25-19, 02:30 PM
  #25  
Depaso
Member
 
Join Date: Jul 2015
Posts: 33
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 14 Post(s)
Liked 4 Times in 3 Posts
Originally Posted by thook

so, how'd you center the "plate" on the spider?
Centered by eye. If lines are marked along the center of the arms of the crank, it is easy. I clamped an old chainring around the inside of the crank and marked the holes with the tip of a thick drill bit.
Depaso is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.