VAC-BAG

Not used one of these kits but have shipped sheet steel in vacuumed bags around the world.

The more air in the bag the more moisture is left for the desiccant to absorb, too much and it cannot absorb any more. So you need to vacuum more air out.

The end of the bag with the tie wrap can never be totally sealed, moisture will continue to get in with fresh air.

Plastic bags are permeable unless aluminised and heat welded shut.

Hopefully the desiccant has enough capacity to get around these issues, vacuuming more air out should help as would heating the dessicant to drive out water before first use and before reusing. 

Last tip is to keep the bag out of sunlight or a room with large changes in temperature, this will drive air in and out of the bag and the desiccant will be soaked. 

As John said, drying the desiccant in an oven before use is important, it it will already be partially saturated. Anyone who has worked with aero-engines or modules will be familiar with packing them in moisture and vapour proof bags - much heavier construction than a vacuum bag, with a moisture proof zip (that can be a pain to close).  Normally, multiple bandoliers of dried desiccant bags are draped over the engine.  The air does not get removed, so the desiccant has to deal with all the moisture in the air and engine.  A paper humidity indicator placed in a window in the bag lets you know whether the desiccant has dried the air sufficiently, or the bag is properly sealed - blue safe and pink unsafe.  You could easily stick one of these indicator sheets in the vacuum bag and it would let you know if the protection is working.

I’m not sure if the design and materials have changed in the last ten years, but one autumn I put my Matchless G9 into a Vac-Bag and sealed it up by folding the open end over several times and securing the bundled end with three cable ties. After about 2 weeks, the desiccant strips were bright blue. I replaced them with new strips and after another week they had also turned blue. When I removed the bike in the Spring, there were patches of rust on many fasteners. I wouldn’t recommend this method of bike storage if you’re intention is to prevent rust. In my opinion it’s far better to put the bike under a cover and just wipe it down every so often to remove any moisture that has formed on it (and at the same time remove any traces of rust). At least that way you can easily access the bike and so are more likely to address any damp issues.

Regards

Tony

Hmm, I was going to try bagging my bikes, I thought about using king size bed mattress bags, - assuming they are long enough, they are only about £5 each, and use desiccant. I planned on sucking out as much air as possible with a vacuum. You should be able to get a pretty good seal with a few big cable ties. I’ll do a bit more research. My other plan was to put low wattage heating tubes under the bikes to prevent condensation. 

Dan

I have read that a couple of bags of kitty litter in the bag will do the job. You only need to get down to about 40% RH and corrosion will stop. Should get you through a winter with a mattress bag.

I have a dessicant dehum unit in my garage set at 40% and bare mild steel never rusts at all.

I too bought a dehumidifier, set it at 45% and over the last couple of years it has worked fine. As Steve says you can store mild steel plate and it doesn't rust. I have no idea how much it costs to run but it's less faff than bagging the bikes and it's convenient for the odd winter run out. 

I have used the Vac Bag system for  all of my bikes. One of the bags is patched with duct tape but I have been pleased with the results. The bikes are stored from November through to about March.

I used to suffer from condensation on them in the garage, especially when there was a sudden change in temperature or humidity. For me, this system has worked. Expensive but worthwhile.

Getting them in, with the stand on a piece of carpet and the padlock and chain fitted is fun but I am confident that that what goes in, comes out looking as good. See photo.