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Tandem Cycling A bicycle built for two. Want to find out more about this wonderful world of tandems? Check out this forum to talk with other tandem enthusiasts. Captains and stokers welcome!

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Old 08-03-11, 06:48 PM   #1
Mainframeguy
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Drain holes

OK, having read this thread on storage I get some ideas about issues now and am starting to feel it is best I "loosen up", consider using storage space at my place of work for prolonged spells off road, and learn how to remove the bottom brackets and see how I get along with doing that (it is likely to be something I only do once I imagine).

I did take advice about where to put drain holes (at each bottom bracket) if I make them and I am still unsure if it is a good idea to do this and have no idea if, having done so, I should use tape squares to cover the holes left from manufacture on the rear dropouts. The advice to grease heavily the seatposts was sound. There is no corrosion of oxidising to speak of there - that is one of the few areas I have been busy with since we got a thud buster for stoker and prior to that considered swapping posts (but I found mine was too long and had to swap back).

I am really sad the bike is going to spend most of it's life out doors on the railings, but I am sure you'll understand if that's what it takes to keep stoker happy then it is for the best - an unhappy stoker means no (tandem) rides.

I think this is going to be a noob question now - but why should the drain holes be at the bottom brackets? I imagined I would just need one and that it could be more or less anywhere along the bottom tube....
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Old 08-05-11, 08:49 PM   #2
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OK - maybe that was too long and maybe I am being anal abotu moisture and the frame - but I think basically I am unsure if my best bet is to attempt to dry, lube, and seal against moisture entry, or if it is best to add drain holes such that there is venting of trapped moisture? Sorry if it is bad to bump thread, but thought that clarification might be useful for any advice.
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Old 08-06-11, 05:16 AM   #3
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The rear BB is the lowest point, also, it should have ports to allow airflow and also water flow from the other tubes into the BB shell.

The FWD BB shell I do not believe has these holes on account of the eccentric. You will want to check this as it if there are holes, it could be where the water entered.

The other reason to keep the rear BB shell dry is that the bottom bracket itself will become corroded and could damage the threads when removed.

With your storage requirements, and likely the climate also. I would seriously consider removing both seatposts, both bottom brackets, the eccentric, and dropping the fork out. Flush the frame with clear water and dry, use a hairdryer to warm the tubes. Make certain it is dry. Locate some Corrosion X.

http://www.corrosionx.com/corrosionx.html

and coat the tubes interiors. Slosh if needed.

Action Tec makes an item called the dry valve.

http://www.actiontec.us/attack.htm

This would give a professional means to add a one way valve to minimize your concerns.

So there is the high tech way.

The info below for drilling would be based on how much water came out of the frame.

As you mentioned drill holes and tape over them. For where you live and what the frame may see over its life, I would drill several 5 mm holes. Using a quality drill bit or better still a unibit, I would add a hole in the rear BB shell (lowest point and centered if possible. I would add one towards each end of the bottom tube (approximately 25mm away from the weld on the bottom centerline), I might even consider adding a hole to the lower end of the downtube.


Truth be told in all of this, you best bet is to stay on top of your maintenance, with frequent disassembly, inspection, clean and lubricate. While apart annually corrosion proofing the frame may be a good idea.

The holes will work and allow easy draining plus application of corrosion preventing materials.

Best of luck with it.

PK
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Old 08-08-11, 08:40 PM   #4
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Many many thanks PK - this is exactly the sort of information I was after and gives me far superior knowledge!

As to how far I can go in achieving a level that really works, or if I need to adjust my expectations and go with the stokers view that we shall simply have a tandeming life that features plenty of "upgrading" without any "retaining" - (IE we use 'em up and wear 'em out I guess)... Well we shall just have to see how it goes.

How it goes so far is that I have removed seat posts, removed a couple of pegs from the underside of the front downtube (were they intended as drainage?), removed a couple of bottle holder bolts, and managed to extract quite a few droplets of water, but probably not all.... A work in progress.

I have decided to change front seatpost on an experimental basis so that there are no shims - hopefully that removes much of the source of ingress.... I shall grease both posts when believe frame dried out.

I think I am going to leave the holes on rear dropouts from manufacture as "breathing holes" - any advice there is welcome.

And last but not least I asked a colleague who has half shares in a sailing boat for some marine grease - he told me the stuff to get is called "Duck Oil" and said that I should NOT spray internally with WD-40 or similar, apparently in the longer term this will react with moisture and do bad things... That advice being directly opposite to the bike shops I thought it worth sharing here....

Right now I am more excited about the changes I have made with removal of my pneumatic seat post and ensuing changes for stoker (bar stem can rise a bit) and trying out slightly sprung saddle for me (stoker reject)... I have never liked the pneumatic stem and hated the shims.... BUT it will mean a change to more traditional mounting and dismounting and that may not suit our urban rides - so I have retained the other stem and it is quite possible with a quick release we could take both, certainly will on the first few trial rides.

But now I am rambling! Just wanted to especially say a big thanks to you PK for excellent advice complete with links!
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Old 08-08-11, 08:56 PM   #5
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Corrosion X is by no means WD40. You might have a look at the link I posted.

PK
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Old 08-09-11, 01:19 PM   #6
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oh yes - I did look at the link and shall be aiming to source that here, thanks, I was just adding the informational that WD40 was recommended by my bike shop for the same application.... And as to the "duck oil" I have no clue if it is preferable or has it's own hazards, but suspect it is more relevant to the packing of the BB bearings than anything else?
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