Byepsycho

Hi, all you cycling veterans.
This millenial is in need of your experience.

I would like to create a sub-compact double, while keeping my road bike's original, 130bcd crank arms by using a Willow Triplizer.
I'm attempting to personalize the gear ratio and preserve my bike's original 80's sexiness by using the Triplizer.

I have a 1986 Centurion Ironman, with a 52x42 crankset and a 113mm bottom bracket.
I would like to get rid of the 52T chainring (outer ring) ((maybe replace it with a chain guard)); replace the 42T chainring (middle ring) with a 46T Triplizer; and attach a 30T chainring to the Triplizer.
I would like to recenter the chainline between the 46T Triplizer ('the new middle chainring') and the 30T chainring that attaches to the Triplizer.

I've read on here that by switching an 80's Ironman 113mm bb to a bb with a 5mm longer spindle typically allows one to switch from a double crank to a triple.
If this is the case, would a 118mm bottom bracket possibly suit my desired purpose? Or would a 120mm bottom bracket work instead?

I'm a known cheapskate amongst my friends on my street, which is why I'm here. I'm finally getting tired of paying people to do work on my bike that I can possibly do my self.
So, before going out and investing on a digital caliper and other tools, I wanted to post this first.
Being that I'm a cheap'azz, I'm turning into a green 'retro grouch' by default; turning others metal trash into my own golden nuggets of joy.

Any feedback would be appreciated. Even negative feedback.

Thanks

1986 Centurion Ironman

Kuromori

You're basically trying to move the inner ring into the old outer ring position, which means ~7-8mm ont he drive side, because that's approximately the gap between chainring teeth, and ~15mm on both sides. The 5mm between double triple is for the drive side, and accounts for the change in chainline and change in point of measurement. The chainline of the outer ring on a triple is ~53(45+8) because the outer is one full ring away from the chainline measurement. The chainline of an outer ring on a double is ~47.5(43.5+4). This is a difference of ~5mm only on the drive side, or ~10mm on both sides, so it depends if you push only the drive side out or try to keep them symmetrical. This is why using the inner two of a triple as a double isn't a great idea. If you do go through with it, a modern chain will tolerate more cross chaining, and it can be run as a triple with triple chainline, but without the big ring. Triplizers are also relatively expensive and also a wear component, so they don't always make economical sense.

TenGrainBread 

The idea you have is way more expensive than getting a new crankset that can handle a 46-30 ring combo.

rccardr 

Might be easier and less expensive in the long run to pick up an 80's Shimano Deore or 6206 triple crankset, which is 110 for the big and middle rings, and 74 bcd for the inner ring. Use a chain guard or cut down 110bcd inner ring as a spacer where the outer ring used to go, then put your large 110bcd ring where the middle ring used to go, and your small 74bcd ring in the granny position. Set it up on the BB just like a triple -a 118mm asymmetrical spindle in a cup & cone bottom bracket will do nicely and not make the NDS arm stick out way far, although a modern 120 symmetric might also do the trick- so that the inner ring & associated mounting bolts miss the chain stay by a couple of mm. With the downtube shifters on your Centurion, should shift beautifully.

You'll also have a marvelous ring selection to choose from: 52 to 34 for the big ring, and as small as 24 for the granny. Plus, because the mentioned crank arms are from the same design period as what's on the bike, it won't look out of place.

pastorbobnlnh 

...another two cents FWIIW on how to save some $$ from the father of a millennial....

I believe you can run the 46T Willow tripliizer as the "outer" chainring, and attach your 74BCD, 30T chainring to the special tabs on the Willow.

Yes, you've lost running a chain guard on the outer position--- but think of the $$ you've saved not purchasing the chain guard and a new bottom bracket--- and you've saved on the sometimes induced headache of trying to determine the correct BB to purchase!

seypat

As others have said the cheapest way to go might be another crank and BB spindle. 110/74, 130/86, or 86BCD are all available. The majority of 110/74s use a 121-123 spindle. The 130/86 I have uses a 3T length. Plenty of rings available on the Bay. Sheldon Brown's BB spindle database will provide some good info. You can pick up cheap, new spindles for around $10. It's hard to beat the price on this ecrank. The seller probably has the BB spindle as well. If not he can tell you the correct length. I would get it myself, but I won't be in that area for a couple of weeks.

https://richmond.craigslist.org/bop/...032618159.html

CliffordK

@Byepsycho's Album

https://www.bikeforums.net/g/user/503094
https://www.bikeforums.net/g/album/16058746



Now that doesn't look like a Centurion Ironman.

Bianchigirll 

The easiest and cheapest part if this evolution will be sawing the teeth off the 52t ring to make it a chain guard

CliffordK

Harbor Freight has digital calipers for dirt cheap, and they're reasonably good. Both English & Metric modes.

However, I'm not sure it is needed for this project. With a couple of exceptions, older Japanese parts are mighty standard (English/ISO).

Keep in mind that your front derailleur may, or may not be able to handle shifting a triple. However, it should be fine if you change to a compact double.

CliffordK

Use the crankset as a lathe/circle guide (and adjust the ring when one gets to the crank)?

seypat

+1. I don't think so.

seypat

Here is Sheldon's spindle database: https://www.sheldonbrown.com/bbsize.html

You can get cheap, new BB spindles for around $10. There are some Sugino AT triples listed on the Bay at the moment. In triple configuration, they take a 3U spindle. I tried a 3T and couldn't get it to work. I didn't try Sheldon's method of 122.5 + a 2mm spacer.

seypat

If he indeed has an 86 Ironman, then the 600 FD will shift a triple. At least the 3 I have will. If it's the 105 FD that came on the 87 and later, it will not. The cage will not travel in far enough to go on the 3rd ring.

Kuromori

You might be able to mount it, but I'm pretty sure the teeth of the small ring are going to be pretty much up against the spider tabs, leaving no room for the chain to actually sit on the chainring, and that's assuming the tab shoulders don't just prevent it from being mounted in the first place.

Salamandrine 

Honestly, I'd farm this one out to the LBS. BB spindle swaps and chainline stuff can be tricky and involve considerable trial and error. You might end up buying several BB.

If you really want to tackle this yourself, I'd suggest starting by measuring your current chainline. Should be 43.5 from the center of the BB to the centerpoint between chainrings. Good chance it isn't. Figure out your math so that the new centerpoint between your new tripleizer small and 46t is going to be 43.5mm.

Consider that getting a new BB or spindle that is say 4.0mm longer will not necessarily shift out your chainrings by the desired amount. Besides the change from asymmetrical to symmetrical spindles, ISO and JIS standards weren't adopted when your bike was new, and also there was plenty of production variance.

If you want this to be easy, buy a new compact crank (or triple) and a new BB that it is known to work with.

CliffordK

There are a few different triplizers. I believe the Willow Triplizers mount like a normal ring, and rotate the bolts for the inner ring to between the arms.



Shimano used a triplizer on some of their cranksets. The 6703 rings are still available, and a triplizer of sorts, but with the inner bolts inline with the outer bolts. In this case, the shelf for mounting the ring has to be ground down flat.


In both cases, a spacer is used to set the spacing between the inner and outer rings so teeth aren't mashing in the wrong spot.

Your 39 to mid 40's ring is mounted as an inner ring, and the triplizer is mounted inside of that.

The outer ring is either mounted as-is, or replaced with a bashguard (or with teeth ground off as per @Bianchigirll.

People have also successfully converted some of the vintage flat spider cranks such as the Campagnolo Strada/Nuovo Record cranks by simply drilling the spiders and adding spacers.



I have thought this modification might also work with first generation Dura Ace cranksets.

pastorbobnlnh 

I happen to have a Willow triplizer and I'll check to see if such a set up could work. More later.

Kuromori

I believe the post I quoted was taking about putting the triplizer in the outer chainring position, not the inner chainring position as designed, hence the comment.

63rickert

OP should do it his way and make mistakes. And fix them. Project requires bolts and spacers and I've no idea what Willow includes. Or what OP has on hand.

Good chance this can be done on original BB spindle. Chainline won't be perfect. If the 30 clears the chainstay and 30 is only used with larger sprockets on rear then it is all rideable. With 46 in same position as 42 once was the chainline in top gear will be bad and only OP knows how much that will be used. And everybody crosschains all the time anyway.

If the 30 hits chainstay or the FD can't move in that far then you get a longer spindle. After trial assembly it will be clear how much more spindle is needed.

Everybody should own a set of vernier calipers. I got mine when 15 years old and they have been the single most used tool for 52 years. But honestly most people can't measure and measure the wrong thing most of the time. Set chainline by eyeball. Calculating everything in advance is fun for some, some find the planning and the calculating the most fun part of project. Then it gets assembled and reality presents.

merziac

Agreed, + many.

Trial and error is priceless if you embrace it, confusing and frustrating in the beginning, absolutely.

But in the long run it will serve you better than just about anything else, save for the proper, good quality tool for a given task.

Understanding, critical thinking and the ability to finesse a process will take you far, instant gratification is not your friend when things go south.

Dig in.

ThermionicScott 

Some of the current thinking around "sub-compact" cranks is actually to keep the ~46T big ring centered with the cassette. That way, one can just stay in the big ring and use the full range of the cassette, only shifting to the small ring for steep and/or long climbs. With modern chains, wear and efficiency aren't drastically worse in the big-big and top gear combinations than they are in the neighboring combinations.

But I agree the OP ought to just go ahead and try things. Experience is the best teacher.

merziac

Especially when tempered with skill, proper tools and most of all common sense, IMO.

pastorbobnlnh 

The Willow Triplizer used as the outer ring and the 74BCD as the inner should work as I mentioned earlier. I cobbled this together from what I had on hand without dismantling anything, so pardon the lack of enough chainring nuts and bolts. The biggest challenge is securing the 74BCD at the mounting hole which lies under the crank arm. The other challenge on this particular crank was that it was already drilled for a 74BCD granny ring. So my spacing is not correct. However, I do believe the spacing would be correct on a standard double crank arm, thus avoiding the need for a longer BB spindle.

Kuromori

There's enough of a gap between the teeth of the granny and the outer tabs/bolts for the chain to sit? Or is the spacing basically equivalent to running a triple outer and granny with no middle, resulting in a large tooth-to-tooth spacing between rings?

Here's the way I see it. Approximating 4mm tabs and 8mm chainring spacing, and using the outer teeth as a reference of 0mm chainline:

0mm - Outer teeth
-2 to -6mm - Spider tab
-8mm - Normal double inner, this is only 2mm away from the tab, so the chain will hit the tab
-12mm to -16mm - Granny position on a triple, 12mm is for standoffs that need additional spacers. There are 8-12mm between chainrings, so there's a large risk of skating or the chain actually going between the rings.

masi61

The person who made Willow triplizer rings I believe went out of business a few years ago. The remaining inventory has been slowly sold off on eBay. I think they had a good amount of the 46 tooth rings remaining whereas the most of the other sizes were sold out.

I bought one one of the 46’s and made a triple from a Dura Ace 7410 crank:




i got busy with other bike builds and I have yet to road test this custom crank. The outer chainrings bolts are flush mounted Shimano Sante’. The outer chainring is a 53 tooth Salsa Professional. I’ll have to double check the inner ring - I believe it is a 28 tooth. Getting this combo to reliably shift required a moderate amount of trial and error on my Cannondale CAAD3 R1000. I believe I finally settled on a SunTour XCD front derailleur and a “dog fang” chain catcher. I shift the front with SunTour Command retro-friction type paddle shifter which is very cool. The whole purpose of this conversion was to make my SunTour Superbe Pro 8 speed cassette 12-26 custom wheelset more capable of climbing the steepest hills. I used an NOS SunTour 115 mm “microlite” bottom bracket (IIRC) and the chainstay clearance for the inner ring stems to be just enough...