Use for old drive chains . . .
 

When we replace a drive chain we put it aside and save it.
Two used drive chains can be utilized as one cross-over chain. Chain wear is nowhere as cirtical on crossover chains.
Anyone else do that?

To quote Rudyard Kipling, "Never the twain shall meet"...

No I don't...I figure if it is 'done' as drive chain then it is just plain done!

Bill J.

Never considered that but maybe its a worthy idea. To me it seems like a chain will lose its lateral stiffness long before it has "stretched" enough to effect its engagement with the sprocket teeth. The loss of lateral stiffness makes it harder to shift - especially with the front derailer. It could very well be that even after a chain has served its life as a drive chain, it may still have a lower pitch than an older sync chain. I've never checked the pitch of our sync chain. I may try this out & see if it is much worse than an older drive chain.

This brings up another controversial subject - rotating tires front to rear. A tire that may be a bit sketchy on the front may be OK on the rear. Tires rotate front to back. Chains rotate right to left.

Seems to me that putting a stretched chain on nice timing rings wouldn't be a good idea.
If you have wornout rings I guess it would be OK.
I replace chains frequently before they reach the point to wear out the more costly cogs and chainrings.

I think the biggest risk would be if the sync rings have worn to the sync chain and have an effective pitch that is considerably greater than the drive chain swapped into this location. For the sync side, so long as the ring pitch & the chain pitch match, it shouldn't cause much of a problem even if the pitch is considerably more than 1/2".

you would need to better define "a bit sketchy" and under what conditions such a swap might be made before I'd accept that recommendation.

In general, rotating tires on a bicycle and in particular on a tandem is done to ensure the front tire is the most new tire on the bike... being the most supple and showing the least amount of wear and tear.

In other words, and assuming neither tire is damaged by road debris or blunt impact, given that a rear tandem tire's center tread compounds wear out about 8x - 10x faster than a front tandem tire's tread compound, the prudent preventative maintenance step -- albeit a bit more time consuming and labor intensive -- is to:

1. Remove and discard rear tires (saving the tube if it's in good repair) once the rear tread compound has been squared off and the casing / puncture strip begins to show through OR has become so thin that nicks in the tire tread compound begin to gape.
2. Remove the front tire / tube from the front rim and reinstall it as a unit on the rear rim.
3. Install a fresh new tire on the front rim using the tube from the discarded rear tire.
4. When the rear tire wears out, repeat the process.

Now, if I damaged the tread or casing of a front tire and didn't have a spare tire AND my rear tire was relatively new and had not yet started to square off I would consider swapping the front for the rear tire as a quick fix to get us to a shop / or back to where we started riding in a guarded manner.

However, as a general rule, if there is a defect in any tire -- a bulge, tread cut, etc. -- then it has no place on a tandem except in the aforementioned quick fix.

I guess by "a bit sketchy" I meant that it is still in sound condition but having more tread left than the rear. No bulges, cuts or casing showing. When the rear tire starts to show significant wear, I sometimes rotate the front to the rear & replace the front with new. However we tend to use steel bead tires that can be VERY difficult to mount. Sometimes it isn't worth the effort to swap them. Our rear tire is starting to show some significant wear and I'm going to order 2 new ones.

We do not rotate tires on our tandem.

A better idea is to use the sync chain until it dies and rotate 3-5 part-worn drive chains every 1000 miles or so. This allows you always to have a clean chain in stock, plus as the chains wear at a similar rate they will continue to work on the sprockets when a brand-new chain would skip. Since the sprockets are expensive and chains cheaper this saves $s.

Doesn't it matter how large the cut is? We managed to get two flats simultaneously by riding over a bunch of screws left on a road. The screws left about a 1/16 inch cut on both the front and back tires. They have lasted awhile, but after getting a large cut in the back tire and reading about the accidents on blown tires, I decided to change both. Think it's ok to use the front tire in the back in the future?

By the way, the new $10 bills don't seem as strong as the old bills (didn't have any $1s). I booted the tire with one, but after 9 miles the pressure blew through 4 layers of the bill. I refolded it however and it lasted the short distance to finish the ride.

It all depends on the cut and how it plays against the tire's construction.

Tires like a Panaracer Pasela use relatively thick and hard tire compounds with a very tough casing and a small cut left by a nail or screw might not deform (i.e., bulge) around the cut when the tire is pumped up to riding pressure... at least for a while.

However, more performance oriented tires with relatively thin layers of very soft compounds and very high thread-count casings will almost always give-way around a cut that penetrates the casing. While you might not feel a 'thumpa-thumpa-thumpa" from the slight bulge, if it's in contact with the road its high profile will be a magnet for accelerated wear and tear and it won't take long before it becomes the source of another puncture. In fact, I've seen more than my fair share of these racing tires deform in a variety of ways -- compound bulging, mysterious s-curve or wave in tread -- after a near pinch-flat where the casing was damaged along the tire's bead.

Bottom Line: When in doubt, chuck it out.

Not surprising that the new $10 bill is not as strong as the old ones . . . better switch to Euros!