I have a question. I have the same crank shown in this link:

https://oldtenspeedgallery.com/owner-.../#.UZOyubXqkZ4



This sparked my intererst "It even came with threads for a third chainring (they weren’t kidding when they marketed it as a touring bike). "

Here's mine:


Is it as easy as bolting on a chain ring with the right bcd and adjusting the friction derailleur (I'm doubting it's that easy)? Would I need to buy a longer spindle and possibly more parts?

Thanks everyone -

It's very likely that you would need a rear derailleur with more tooth capacity and a longer cage to take up the extra chain when in the small chain ring.

Not so easy, you have to select a ring size that will allow a clean shift and bolting to your existing crank does't easy. May I suggest a larger capacity freewheel/cassette if you trying for lower gearing.

I have a similar Sugino crankset to which I added a third smaller chainring. The chainrings I used are 52T, 40T and 28T. You will likely have to use a longer spindle to get the proper chainline and use a front derailleur designed for a triple; you may or may not need to change the rear derailleur depending on its cage length. Also, make sure that the small chainring you use has no more than 12T difference with the middle chainring for good shifting. I found that I could use a 28T with a 40T, but when I tried a 42T in the middle, the 28T was too small (so I'm now looking for a 30T to use that 42T).

Some cranks with third ring provisions might also need the proper bolts and bushings to properly space the thrid ring away from the middle one. Crankset makers usually provided these if it is needed for their cranks, but sometimes the bike manufacturers do not bother to include them when they sell a bike. No problem back when the bike was a current model, but as the years go by, the bushings and bolts might be harder to find. Your crankset might not need any special adaptor bushings and bolts, but it is still something to watch out for when trying to add on a third ring to a crank.
I have a nice NOS Stronglight Delta crank with threaded holes for a third ring at the back of the spider........Haven't been able to add a third ring as the bolts and bushings for the crank seem to be quite unobtanium these days.....

Too go with leecycle's post above, you'll find you'll need a triple FD if you use more "equally" spaced chainrings. Double FD will work better [as a and] on triples if they are in a half-step+granny setup (like a 52/44/28). Or at least that seems to be the case with Suntours I've done this to.

That is consistent w/ what I have always read. It has to do with the profile of the inner cage wall.

I continued to use the original road double front derailleur on my PKN-10 when I switched from the stock 52-42 to 48-45-34. I changed that to 52-48-34 for my son, but he made me replace the 48 with my 45, which still seemed to work fine.

The secret to accommodating small inner chainrings is to make your outer chainrings as small as practicable.

I have found the following non-triple specific FDs to work with triple cranksets:

• Suntour Cyclone 1st gen
• Shimano Altus early 1980s
• Shimano 600 mid-80s
• Shimano Thunderbird, vintage unknown, probably early 80s

I've converted 3 double chainring bikes to triples without needing to change the spindle. YMMV.

How's the current clearance between the chainring and the chainstay? Is there room for another ring? That's really the only problem with spindle length. My LBS had the right bolts for my Sugino. It's the same as for the outer rings but you don't use the nuts and the bolts, just the bolts.

How small are you going on the third chainring? I'm sure this counts, here.

Also the Mountech FD

Lots of great info, thanks everyone. I'll see how the frame clearance is tonight and check on the model of derailleur (all I know is it's a suntour) tonight. Assuming the room is there I might as well try it out. Right now I'm running 52-40 on this bike and it's a little much for some long steep hills. I also have a touring bike that came stock as 50-46-28, I was wondering why the first two rings were so close together and what 'John E' eluded to regarding the smallest possible outside ring maybe well be the reason. Maybe I'll just pull the drive side crank off both bikes and see how the 28t plays with my 52-40 setup if I can find time this weekend. I'm getting married in 6 weeks and the planning is really cutting into both riding and wrenching/tinkering time

If the triple isn't easy or cheap to do I'll just buy a 34 or 36 chainring and hope it works with 52.

I believe that type of gearing is known as "half step with granny"

https://forums.roadbikereview.com/ret...ny-207677.html

All my triples have 36T inner chainring. If I could get a larger 74BCD inner chainring, I would.

Campagnolo didn't bother to make a triple FD for their Record Triple crank. The old NR/SR FD works just fine.