Over the weekend I bought a bike for a co-worker that wants to start cycling, an older Univega Gran Tourismo. It has an older (obsolete) SR APEX triple crank with a BCD of 118. It seemed to drive ok when I tested it, but apparently I didn'y ride it long enough or hard enough when checking it out. After overhauling, cleaning, and gettign it ready to roll, the shakedown cruise revealed a serious issue.

The problem is that it seems the teeth on the outer chain ring are rounded over enough that when you get going pretty good the chain slips and jumps over the teeth in a random (and sometimes painfull!!) fashion. It works ok on the stand, but under real world load it skips. I've checked the BB, the FD, and the alignment of the chain rings - nothing's bent or broken, and the FD has been R/R'ed with no success. I'm pretty positive the worn teeth on the outer chain ring is the culprit.

So, I'm begging here. I tried to be altruistic and do a newbie a favor, and it bit me in the ass - big time. Does anyone have one of these rings, a decent triple crankset that they can part with, or even a link to where I can buy one?

118 is a tough size, as is 116. I have had very good luck using a Dremel tool and an electric drill to adapt 130mm chainrings for use on a 128mm BCD Nervar Star spider, so you might be able to play this game, as well.

Thanks, I'll look into that, but I don't think I have any spiders/rings that can be made to match. I'll dig around in my box o' junk and see what I might be able to come up with.

Another idea - would a mtb crank work ok in place of the road crank, or is it too wide? I'm thinking I might just swap out the old, obsolete crank with an inexpensive mtb one. I have a box full of mtb FD, so that shouldn't be an issue. That would give the new rider better gearing - a smaller granny and a smaller top ring - that SR has 52 teeth on the outside, and 36 on the inside. Heck, the middle/small is practically a "modern" compact!!

Originality and/or "period correct" is not an issue - it needs to be functional and reliable.

Anyone got one they can part with?

Some mtb cranks might work well for you. I currently have a Sugino mtb triple on my PKN-10.

I have the Sugino double pictured which I bought cheap on ebay and haven't used. It is NOS in it's box and never mounted. The outer ring (52 tooth) is not replaceable, but the inner rings (42 & 38 tooth) is 110 bcd and easy to find in many sizes. PM me if this is of interest. I can also take a look at the dump. Currently low end Fuji and Nishiki lean against the side of the shed. They have cheapo double cranksets. I'm not certain what brand.

I have no definitive information, but I haven't heard of significant differences in bottom brackets on older bikes between road and mountain.

My guess (and that is all that it is) would be that if you have a square taper bb, you can replace it with any crank for square taper as long as the rings clears the frame. (Ignoring any special cases, like I seem to recall Campy had a slightly different square taper)

Tell me, is this the ring? It's not available for sale/trade, but I might be able to dig one up for you at the LBS.

And for the record, they were used on the '83 Schwinn LeTour Luxe - might be worth it to dig up that recent thread on them and bug the members who converted theirs to singles or fixies. Gotta love the fixie folks - they're doing a great job supplying us with rare outer rings!

Take care,

-Kurt

bigbossman,
Please clarify what this means. What am I trying to measure here?
Happy to help if I can.

Take a look here: https://www.sheldonbrown.com/gloss_bo-z.html

A BCD (bolt circle diameter) of 118 translates to an adjacent bolt hole center-to-center measurment of 69.4mm. Example pic (from Sheldon's site) attached.....

Thanks for trying to help!!

That looks like it, 'cept the one I have had a bash-guard ( I removed it). The center-to-center on the adjacent bolt holes should be 69.4mm. Any help would be appreciated.

Went searching at the LBS for one, and pulled out one, but as it was marked Ritchey, I can imagine what the LBS would have charged me for that one. Will check with some other shops down here - wish me luck.

-Kurt

There are a few SR rings on ebay right now with 118 BCD. BIN for $14 shipped. 52 & 53 teeth. One 52T for $26 BIN shipped
I don't know whether or not you can just any chainring with 118, I'm no damn mechanic
Just search for 118 BCD

Don't know
good luck

D'oh!!

Why didn't I think of that? Thanks!

This guy has 6 for sale; $9.99 BIN. I have bought from him in the past.... no hassles.

52t 118 BCD

Dogbait

Hi, I have a 42 and a 52 118 bcd If anybody is really stuck. i could use something under 39 118 bcd for climbing liamo