Transport bike in the rain

[Caerus]

I'm going with the chaps that have actually had this happen while transporting their bikes. I'll be cling fliming & using black bags where necessary when I hit the road in two weeks.

 

Why even take a chance

[Nickzta]

I agree with Johan.

 

High speed, 100km/hr and above with wet/damp air will force water through every grease sealed crevice and opening. The rear of your car has a wind free zone. The bike will get wet, but it won't have direct windforce.

 

 

 

You may not see the damage for 6-9months, you may not feel it for 2 years, but once water get's onto unprotected metal. It's going to cause damage.

[Tjokkits]

I agree with Johan.

 

High speed, 100km/hr and above with wet/damp air will force water through every grease sealed crevice and opening. The rear of your car has a wind free zone. The bike will get wet, but it won't have direct windforce.

 

 

 

You may not see the damage for 6-9months, you may not feel it for 2 years, but once water get's onto unprotected metal. It's going to cause damage.

 

 

is it really wind free behind a car? reason i am asking is when i do gravel/dust roads with my bike on the back two things are guaranteed to hapen, my X9 shifters stop working and my mavic hub screams at me, need to open all up clean and lube before i can go any further

[flymango]

 

Who are you TNT? Please state your name and occupation.

Explosives expert. Blows up bridges when he gets to them.

[rob_mtb]

is it really wind free behind a car? reason i am asking is when i do gravel/dust roads with my bike on the back two things are guaranteed to hapen, my X9 shifters stop working and my mavic hub screams at me, need to open all up clean and lube before i can go any further

I think there is a lot less wind at the rear. Certainly not wind free. What happens is the air flows past the bike and creates a static charge, which the fine, light dust treats as a magnet. I have this same issue with my towbar mounted Thule. Only soluition I've found is black bags. I will try out that glad wrap idea though.

[Nickzta]

Lot of opinions again, but no fact. My pressure washer (and yes I use it to clean my bike) delivers water at a pressure of 110 Bar.

 

The equation to get water discharge velocity:

 

V = Sqrt (2 x g x h), where V is velocity, g is the gravitational constant and h is the water "head".

 

To convert "head" to pressure: P = rho x g x h; thus h = P / (rho x g), leaving V = Sqrt( 2 x (P / rho))

 

This equates, without losses to 148 m/s. With a small round orifice like the head of a pressure jet, the loss factor is roughly 0.6.

 

Thus the expected water velocity is 60% of 148 = 89 m/s

 

89 m/s = 320 km/h

 

So no, at 1/3 of the velocity of a pressure hose, I do not think the water ingress will be a big deal.

 

I believe that if it cant hurt you it cant hurt your bike. and very honestly, i did the experiment by sitting on a bakkie in the rain before, water at 100km/h does not hurt on your body (maybe a little on your face)

 

Hey, I used to think the same.

My motorbike (a classic streetfighter) was dirty and I wanted to wash it quickly. Everybody said not to use high pressure - but I decided to anyway, I was in a rush. Two months later I notice that the nut on the axle is showing rust damage. It was 'cos I forced water through the seal when I rinsed the bike.

Edited December 9, 2011 by Nickzta

[rob_mtb]

Explosives expert. Blows up bridges when he gets to them.

Not too sure about this, my cash is on him working at a bike shop. Bets anyone?

[TNT1]

Not too sure about this, my cash is on him working at a bike shop. Bets anyone?

 

No chance. I work in info-sec. Weedmod is the casual bike shop employee.

 

Oh, and I touched 160ish on the R21 in the rain on the way in this morning. Will let you know how the bike is tomorrow. Like I said, if water is forced into any sensitive areas by that, it will go straight back to BMW.

Edited December 9, 2011 by TNT1

[TNT1]

Explosives expert. Blows up bridges when he gets to them.

 

Only when I've run out of matches. I prefer a slow burn. With s'mores.

[gummibear]

is it really wind free behind a car? reason i am asking is when i do gravel/dust roads with my bike on the back

There is less wind but your tyres shoot up gravel

I drove from PE to Cape Town a few years back and at Storms River there was a accident with a truck and the road had been close.Traffics then sent us along a gravel road to avoid the accident scene.My bike was sand blasted from the sand and gravel.The gravel damaged my rims and my downtube was almost polished aluminium.The crank also wasn't so shiny anymore.

That's why i now wrap my bike when i travel in wet or dry conditions.

Edited December 9, 2011 by gummibear

[Pieterg]

dry it and lub it

[Nickzta]

is it really wind free behind a car? reason i am asking is when i do gravel/dust roads with my bike on the back two things are guaranteed to hapen, my X9 shifters stop working and my mavic hub screams at me, need to open all up clean and lube before i can go any further

 

Yes, you are right. There is much turbulent air back there. It will swirl and cover everything with dust.

 

The problem here is the direct (straight-line) force of wind. You have the speed of the car and the slipstream that combine and blast. Normally that's okay, but in wet weather it's going to force the water into places where it normally wouldn't go.

[Sharkie 2]

Funny how the one hubber always needs to be smarter than the other

As many have said so far it won't do any harm, I clingwrap the most important areas on my bike if I transport it in the rain, just for peace of mind sake nothing else

[Sammajoor]

Explosives expert. Enjoys a good Blows up bridges when he gets one to them.

 

There I fixed it.

[Johan Bornman]

The assumption seems to be that all bikes are created equal and that all thus have the same bearings. The other assumption seems to be that it is only bearings under threat. There is more to it.

 

Two important truths about rotational seal design are:

 

1) A single seal cannot separate two liquids and paradoxically;

2) A seal that doesn't leak, leaks.

 

Point one. If you have two liquids - water and grease/oil, you cannot protect the bearing with a single seal. Good hubs thus have a contact seal as the inner seal and a labyrinth (non-contact) seal as the outer seal. A labyrinth seal can be visualised by holding your hands in front of you whilst making two Cs with your fingers. The right one will be a mirror image of the left and reversed. Now lower your right hand until the two Cs intersect and bring it closer together. The cavity between them will be S-Shaped. Now rotate the two against each other and you have a visual representation of a labyrinth seal. It does't make contact and is only splash-proof, not submersible.

 

The second seal is a contact seal or wiper seal. It has to follow law number two.

 

Point two: If a rubber seal is not lubricated, it will burn away and no longer seal. Its lubrication comes from the inside and is the same grease that greases the bearings. It is designed to slowly leak out so that the seal is lubricated. The grease inside the bearing is thus a consumable and once there isnt enough left in there to leak out, the seal burns and stops making contact and stops working and hence stops burning. By burn I mean rub away like an pencil eraser rubber on a table. The fact that the seal leaks is evident from bearings. You'll see after use that the bearing pushes out a little bit of grease.

 

Now, since the seal actually leaks (so that grease can come out) it also allows water to come in. Water in contact with such a seal whilst it rotates, can get in.

 

All good hubs are protected by these two seals. Most people erroneously refer to the labyrinth seal as a dust cap, which it isn't.

 

 

Some components, like the right hand side of some Shimano rear hubs, are only protected by a labyrinth seal and water is easily forced into these hubs. Many headsets only have a labyrinth seal at the top and nothing at the bottom. That's because water usually drips onto the bike from the top. (They seem to have forgotted about the stream of water shot up by the wheel, but that's another story).

 

Some hubs, like DT Swiss and Mavic, are very poorly designed an either side and have no labyrinth seal protecting the bearing. Water is easily blown into these hubs. Hope hubs juse a combination of O -rings in addition to the cartridge bearing's own seal. However, between the freewheel body and hub itself, is a plastic ring that doesn't make contact and acts as a sort-of labyrinth seal. Not submersible and will certainly leak if sprayed.

 

Modern external cup BBs are also poorly sealed. The plastic press-fit spacer is a disfunctional labyrinth seal. BBs in BB shells without drainage holes are particularly vulnerable from water entering from the seatpost and eating at the bearings from the inside out.

 

Cable ends are not sealed against water at all. Even a light spray easily penetrates cable housing and ruins the cable a few weeks down the line when it starts to oxidise and become tardy in moving around. Most mountain bikes ship with exposed cable runs and it is easy to see what water does to this. We have discussed this here often and it is not difficult to see that an, even gentle spray of water, will do to these cables.

 

Pedals, especially slightly worn Shimano and Crank Bros pedals have very delicale contact seals at the inner end of the axles. Once these are worn, water is easily blown in there and trapped against the small little bearing that quickly rots.

 

Lots has been said about how tough seals are. Well, they're not. If you inspect them you'll see that the rubbing end is a thin, tapered lip that is easily flapped around by a bit of compressed air or water jet. However, this is not the big issue. Once they are slightly worn and no longer making contact, water will penetrate very easily. Although a bearing with a worn seal is not completely destroyed yet, water in there will just cut its life short.

 

Sprayed water also carries contaminents with it. Shifters - mountain or road, have open designs. All that protects it is an unsealed cap. Grit and muddy water from road spray easily penetrates these and impairs function over the long run.

 

I remain convinced that a long ride on the roof of a car is not good for the bike.

Edited December 9, 2011 by Johan Bornman

[RodTi]

For what it's worth - I only drive in reverse when I have my bike on the back and it's raining, since that way the water is hitting the bike from before-the-after - and it doesn't get any wetter than what it was before it was dry.

 

Works like a charm. So all you clever people with your mumbo-jumbo newfangled science can go take a long walk off a short pier - coz science only works in some places.

 

Like, doh.

 

 

 

That is all.