i just picked up a big blue and silver moto grand touring of vitus 888 with an on-frame hanger and dt shifters! woo hoo!

but ... the lower bottle boss on the down tube hasn't any threads. it's just a hole. the upper boss is fine.

what do you suggest?

clamp it?

i'm in seattle if you think i should take it to a frame builder. but it's gonna be a cheaper rebuild: just adding fizik tape and new hoods after a full overhaul.

-bill

Probably would be really simple to just run a tap through it.
Pretty odd mistake, though, reminds me of my Trek's fork, which has one threaded eyelet and one smooth one!

Look up rivnuts

Apparently they are rather easy to replace, and your bike shop should be able to help you with it.

If the boss is there but it just isn't tapped, just get the right size tap and tap it. It is a metric M5x0.8 size. Keep in mind that any metal shavings will go down the tube and into your bottom bracket. You can keep some of these shavings on the tap flutes by heavily lubricating the tap with bearing grease. Even then, you might want to overhaul your BB when you get a chance and try to flush the tube you tapped once you have the BB bearings removed.

If there is no boss, a rivnut will work but again it will have to be drilled to the proper size so the same advice above applies.

sorry, poorly worded. no boss at all ... er, just one of the two bosses exists.

thanks. i'll research rivnuts.

'deliverance' comes to mind for some reason.

If the boss is missing and there's a hole, I'd do it right and braze a boss in the hole. You'll want to choose one that comes as close as possible to the appearance of the existing bosses on the frame. The downside is that the area around the boss will have to be repainted after brazing. Personally, I think riv-nuts are kludges.

Nova water bottle cage bosses

Nova water bottle cage boss reinforcement

thanks, scooper.

i called seattle's cyclefab. he said he could braze it for $20, which sounds like a deal. but it would hoze the paint around the fitting, and i'm unsure about that with this inexpensive rebuild and the great paint on the bike already.

"kludge" may define me, personally.

They are inserted in the hole and set with a pop rivet tool, stopping before the stem pops. Then you unscrew the stem leaving the threaded sleeve in the hole. The thread will probably be smaller than the 5mm in a regular boss. The ones I have are 8-32.

Edit: the ones above are 5mm.

pretty!

Not a kludge, a temporary repair and very easy to do, here is how to do it with a quick release skewer.
When the frame is ready for new paint have it brazed!
Park Tool Co. » ParkTool Blog » Water bottle fittings

I suspect the original boss wasn't brazed on that well, and there was a gap between it and the down tube. After a long time with moisture dripping down from the water bottle and cage, some corrosion developed in the gap and eventually caused the boss to pop off and it must have come off all together when the last water bottle on the bike was unborn from the frame.

Yep, if you don't want to repaint, just rinut one in. With a cage on top you'll never even see it. If and when you want to repaint it, braze in a new one for the $20, like m_sasso said.

trying to figure this out... i realize i need an aluminum (not steel) rivnut in size m5x0.80 as a couple of you have already noted. this page shows a good tutorial like the one m_sasso posted:

https://barndoorcycling.wordpress.co...sing-riv-nuts/

edit: bought this: https://m.ebay.com.au/itm/231290989512

The boss that is still there in the picture appears to have a gap all the way around it. Is it a rivnut?
A brazed boss shouldn't have a gap like that.

Eagle eye. Yep, it looks like they're riv-nuts and the lower one just pulled out.

Silver brazed boss:

Make sure to practice a couple of times on a test hole in a scrap piece of metal. The aluminum rivnuts in particular are easy to over tighten and tear themselves apart. By the same token you can under tighten it and it will just spin or fall out. It takes some practice and finesse. After you install it you can lightly tap the outside flange to get it to be better contoured to the tube.

Why use aluminum Rivnuts?

Get WATER BOTTLE BOSS OPEN ENDED

5mm THREAD WITH 8mm TOP

Use J-B Weld, works like steel.

Better than riv-nuts, for sure.

Cinelli Water Bottle Cage Boss - $0.63 ea.

A full water bottle wants to rock from side to side as you ride. I'm not convinced that a glued joint will hold up. J-B Weld is just glue with powdered metal added.

thanks. one of the sites mentioned tightening the skewer tool with the same force used to secure a wheel.

JB-Weld has a tensile strength of 3,960 PSI (27.3 MPa) when cured. A water bottle cage boss secured with it is not likely to fail under normal use.

Marine-Tex Epoxy Putty is similar and has a tensile strength of 4,000 PSI (27.6 MPa) when cured.

Silver brazing alloy filler has a bulk tensile strength of ~40,000 psi (276 MPa), or an order of magnitude higher than J-B Weld and Marine-Tex.

just going by what i read online in the tutorials for this particular application.

aluminum seems like it would be far easier to secure with a skewer against the thin tube wall.