Rim/Spoke failure

For discussions about bikes and equipment.
Brucey
Posts: 35939
Joined: 4 Jan 2012, 6:25pm

Re: Rim/Spoke failure

Postby Brucey » 16 Feb 2015, 6:51am

SCC of brass is well known as a major problem whenever there is any ammonia present, but unless you roads are covered in poop (or possibly they are using urea for de-icing which is somehow decomposing to give ammonia) then there shouldn't be any ammonia present. Which leaves MgCl, NaCl etc that is used for road de-icing. This can also cause SCC in brass but it isn't so well known.

What is well known is that the stronger the solution of any corrosive agent, the worse the problem. Leaving your bike dirty and letting the crud dry out is a bad idea; the strength of the corrosive solution can increase dramatically. Washing it off is a good idea; even leaving the bike out in the rain might be better than leaving it to dry out.

I have often noted that commuters see the absolute worst of any corrosive conditions; the bike gets ridden every day in the foulest weather, and furthermore it gets ridden only a short time after the roads (especially main roads) have been freshly dosed with de-icing agents. You could hardly contrive anything worse in terms of making a bike corrode.

cheers
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mig
Posts: 2062
Joined: 19 Oct 2011, 9:39pm

Re: Rim/Spoke failure

Postby mig » 16 Feb 2015, 8:47am

is the valve hole in the rim (over) large? i.e does it allow water in easily?

Two_Trooper
Posts: 13
Joined: 25 Jan 2015, 12:15pm

Re: Rim/Spoke failure

Postby Two_Trooper » 16 Feb 2015, 4:41pm

Brucey wrote:SCC of brass is well known as a major problem whenever there is any ammonia present, but unless you roads are covered in poop (or possibly they are using urea for de-icing which is somehow decomposing to give ammonia) then there shouldn't be any ammonia present. Which leaves MgCl, NaCl etc that is used for road de-icing. This can also cause SCC in brass but it isn't so well known.

What is well known is that the stronger the solution of any corrosive agent, the worse the problem. Leaving your bike dirty and letting the crud dry out is a bad idea; the strength of the corrosive solution can increase dramatically. Washing it off is a good idea; even leaving the bike out in the rain might be better than leaving it to dry out.

I have often noted that commuters see the absolute worst of any corrosive conditions; the bike gets ridden every day in the foulest weather, and furthermore it gets ridden only a short time after the roads (especially main roads) have been freshly dosed with de-icing agents. You could hardly contrive anything worse in terms of making a bike corrode.

cheers


+1 on this, makes perfect sense, I had a 16ft hamilton jet, the engine block was steel and the jet & heat exchangers were aluminium. I had to replace the sacrifice tab between the block and jet a few times, as the water was slightly salty it created a voltage differential between the two metals- speeding up corrosion. As quoted, looks like the washers are steel, reacting with the salty water/road treatment. Swapping the washers out for brass may help, but rinsing off the road salt after a wet run may help.

JohnW
Posts: 6234
Joined: 6 Jan 2007, 9:12pm
Location: Yorkshire

Re: Rim/Spoke failure

Postby JohnW » 16 Feb 2015, 6:44pm

Two_Trooper wrote:.............I had a 16ft hamilton jet, the engine block was steel and the jet & heat exchangers were aluminium. I had to replace the sacrifice tab between the block and jet a few times, as the water was slightly salty it created a voltage differential between the two metals- speeding up corrosion. As quoted, looks like the washers are steel, reacting with the salty water/road treatment. Swapping the washers out for brass may help, but rinsing off the road salt after a wet run may help.


..................if you have a private jet, why do you need a bike? :lol: :lol: :lol: :lol: :lol: :lol: