Chain Ring Bolt replacement?
 

TLDR, need chain ring bolt for old 80s? roadbike. Puch Pathfinder 10 speed. Sugino crank? Seems to not be a common size. Pics (apparently Im not allow to upload pix for you to see the bolt...) Youtube search "Vintage Bike Chain Ring Bolt ampecsu"

Hi I'm new here...
I just bought an old Puch Pathfinder 10 speed that I've noticed was missing a single bolt after the chain kept popping off after initially riding fine for 15 min... Guess I wasn't thorough enough in inspecting it at purchase. It may have been jb welded prior.

Anyway, I've been to 3 local shops and none have anything this small in diameter and 2 recommended that I try a recyclery that is possibly due to reopen this month.

Any leads or tips on finding this bolt or another solution? I've checked ebay. The crankset says Sugino if it matters.

Thanks

I grabbed a couple screenshots of what you've described. I worked at a shop amid that era of bikes but don't recall coming across bolts like these. Than again, it's not really the type of crankset a person would be disassembling so maybe they came through the shop but we never touched the ring bolts. Are they close enough to standard bolts that the spider & rings could be drilled out without removing too much material?

https://cimg6.ibsrv.net/gimg/bikefor...dea9fb0d0c.png
https://cimg7.ibsrv.net/gimg/bikefor...90e474aeda.png

Thank for doing that!
How "close" should the size between standard bolts and mine be. I think I've read that there are actually different sizes of "standard." Whats the smallest?

The nut or sleeve part of bolts I have measures .38 inches, so a 25/64 drill bit would open up the holes for use.

I looked at the picture - I likely have (more than) one.

Can you measure accurately these things:
Total length
Diameter of threaded section
Length of threaded section
Diameter of unthreaded section
Length of unthreaded section
Diameter of head

If I have a match I will get a postal address and it's yours.

Those look like the bolts used to attach chain guards to the outer ring. I don't have any to offer, but perhaps if you can rummage through the parts bin of an LBS or bike co-op you might find a crank with a chain guard attached with that style bolt.

Small chance a rivnut and a button head cap screw might secure things- time to pull the crankset anyway and clean it up.
i see fitting, hacksaw and files needed to accomplish if the correct part cannot be found.
possibly a T nut too but spot facing the back to get the base flush will probably be required.

small obsolete parts that were never easy to find are a problem. A TA chainring fastener for the 6 point intermediate ring might work too... another easier to find part but expensive as a set.

*cant fix font...

Thanks guys! I came across (cant post links; search for)

SUGINO BOLTS CHAINWEEL CHAIN GUARD NOS CRANK SET ROAD TOURNEY BICYCLE VINTAGE

...on ebay and just ordered them to see. Can always return them. What do you guys think?

I'll try to measure what I have.

And yes, definitely will be cleaning things up!

Update / Measurements

I uploaded another video on youtube under "Sugino Chainwheel replacement bolts ampecsu"

The ordered bolts are shorter and do not fully thread though...the amount in which they do is pictured at the end in the video. Does it look like a big issue??

Does this vid help my cause any?

anyone?

Yes. I will have a look in the boxes in the cellar, will get back to you, will send a pm.

In the meantime,

a) almost all of the stress in a bolt-nut connection is taken by the first three threads; and
b) you have four other bolts holding the ring on.

I'd take the bolt out and thread it in to the same depth, count the threads, and if it's two or more tighten it and ride.

That sounds promising. Also the Re-Cyclery that some shops recommend I try may have re-opened so I can check with them Tuesday a.m.

Just sent you a good news pm.

I need to make more post to see it..

I'm thinking of putting a rear view mirror on. Seems like a good idea

WOW! I got really lucky today while selling a washing machine and dryer for my aunt. The buyer had an old bike on the back of his truck that he was throwing out. He said I could have it and it has a Sugino crank? on it. I took off a bolt and it fits mine and maybe just treads out an extra 2 mm but nowhere near enough to get in the way of the chain.

(10th post for privileges)

It also has some safety brake leavers on it and wider drop handle bars that I think I'll switch out!

I just ordered thumb shifters from bikerecyclery.com, and they are shipping tomorrow, so they are definitely (back) in operation.

Open Mon Wed and fri. By appointment but I could not get through...