rickpaulos
Well-Known Member
We recently tuned up a Cannondale tandem that had 6 loose mounts on the frame. 4 water bottle and 2 rack.
The tool of choice was Harbor Freight's Doyle brand rivnut setter kit. $49.99
www.harborfreight.com
There are some vids at hf site showing the tool in action.
This tool is owned by friend and I was impressed. Mainly because the curved handles work well for bike frames. I've seen other rivnut (blind nut) tools that had straight handles that were way too long to fit within the main triangle of a bike frame.
Years ago I made my own tool using a quick release skewer and some hardware. The skewer threading is the same as water bottle cage mount bolts. Although a full skewer is too long for the lower nuts. I cut one way down and rethreaded it. I used it to put new aluminum blind nuts in my titanium frame bike. Due to the odd tubing shape on this particular frame, the original blind nuts didn't hold well.
RivNuts, rivet nuts, blind nuts, etc. Different names for the same thing. They are used on most bikes. Previous steel frames got brass brazed in nuts. Blind nuts are far faster to install and work on steel, carbon fiber, aluminum and titanium frames.
Rivnuts are made in aluminum, zinc plated steel, stainless steel, etc. Sold in many SAE and Metric sizes.
This particular Cannondale had stainless steel nuts in an aluminum frame. That's a problem because of galvanic reaction. An electrical reaction when 2 different metals touch. My guess is the nuts loosened up due to the differing metals slightly dissolving where they touch. The existing water bottle cage nuts were tightened up, not replaced.
The seat stay rack mounts were a huge challenge. The bolts were cross threaded and the nuts were turning freely in the frame. Lots of rattling there. Trying to keep the nuts from turning with the bolt took 2 people and some mini crowbars to apply pressure on the nuts. We were focused on not messing up the paint.
I always use grease on water bottle cage bolts. It looked like the bike owner used anti-seize which is typically recommended to keep stainless steel threads from galling. The bike had been rather wet on occasions. I suspect mostly on a rear car carrier at highway speeds. That drives water deep in to any bicycle and water is the fuel for galvanic reactions. IMO, buy a mini van to transport your good bikes inside, not an external bike rack for your other car.
Trying to drill out loose blind nuts is a problem too. Most drills are too big to fit withing the frame, the nut will want to spin, you may gouge out the frame making it impossible to install a new nut, etc. Tightening existing loose nuts should be the first attempt. I've seen bikes with cages clamped on with auto hose clamps, ugly and the sharp ends stick out. I've seen cages taped on. I've seen bikes with self taping screws, arg! Rubber strap on cages never stay put. I got an aluminum Trek that had a hole the size of a dime where someone tried to drill it out at an angle, then covered the mess with a decal.
The tool of choice was Harbor Freight's Doyle brand rivnut setter kit. $49.99
10 in. Professional Rivet Nut Setter Kit
Amazing deals on this 10In Pro Rivet Nut Setter at Harbor Freight. Quality tools & low prices.
This tool is owned by friend and I was impressed. Mainly because the curved handles work well for bike frames. I've seen other rivnut (blind nut) tools that had straight handles that were way too long to fit within the main triangle of a bike frame.
Years ago I made my own tool using a quick release skewer and some hardware. The skewer threading is the same as water bottle cage mount bolts. Although a full skewer is too long for the lower nuts. I cut one way down and rethreaded it. I used it to put new aluminum blind nuts in my titanium frame bike. Due to the odd tubing shape on this particular frame, the original blind nuts didn't hold well.
RivNuts, rivet nuts, blind nuts, etc. Different names for the same thing. They are used on most bikes. Previous steel frames got brass brazed in nuts. Blind nuts are far faster to install and work on steel, carbon fiber, aluminum and titanium frames.
Rivnuts are made in aluminum, zinc plated steel, stainless steel, etc. Sold in many SAE and Metric sizes.
This particular Cannondale had stainless steel nuts in an aluminum frame. That's a problem because of galvanic reaction. An electrical reaction when 2 different metals touch. My guess is the nuts loosened up due to the differing metals slightly dissolving where they touch. The existing water bottle cage nuts were tightened up, not replaced.
The seat stay rack mounts were a huge challenge. The bolts were cross threaded and the nuts were turning freely in the frame. Lots of rattling there. Trying to keep the nuts from turning with the bolt took 2 people and some mini crowbars to apply pressure on the nuts. We were focused on not messing up the paint.
I always use grease on water bottle cage bolts. It looked like the bike owner used anti-seize which is typically recommended to keep stainless steel threads from galling. The bike had been rather wet on occasions. I suspect mostly on a rear car carrier at highway speeds. That drives water deep in to any bicycle and water is the fuel for galvanic reactions. IMO, buy a mini van to transport your good bikes inside, not an external bike rack for your other car.
Trying to drill out loose blind nuts is a problem too. Most drills are too big to fit withing the frame, the nut will want to spin, you may gouge out the frame making it impossible to install a new nut, etc. Tightening existing loose nuts should be the first attempt. I've seen bikes with cages clamped on with auto hose clamps, ugly and the sharp ends stick out. I've seen cages taped on. I've seen bikes with self taping screws, arg! Rubber strap on cages never stay put. I got an aluminum Trek that had a hole the size of a dime where someone tried to drill it out at an angle, then covered the mess with a decal.