E.R.D. Tolerances - Swapping A Rim
 

The rims on my old bike are pretty darn near the end of their service life - 18 years and 10 000 kms later. I want to switch them over before something goes terrible wrong and I'm stuck with a buted wheel.

The hubs I have are currently fine (I service them well) so all that I need to do is get a new set of rims, and reuse the spokes (which are also in good condition). Problem is that my rims are 36H araya px-35s.... which they stopped making quite a number of years ago. The E.R.D for this set of rims is 614.0mm. I've located the Rhyno Lite rims at my LBS for $30 a pop, so they look good as replacements, BUT with an ERD of 612.0mm.:(

So, is this a doable (read *workable*, not *perfect*) replacement? Does a 2 mm difference make or break? If it helps, I've got visible threads on the spokes above each of the nipples with the current rims, so my thinking is that this could take up the slack.

First of all you're operating on a few false assumptions.

1- unless you're planning a long trip, or the rims are already showing stress cracks, or brake track wear, the only thing you're preventing is the need to rebuild a wheel, by doing it sooner. Wait until the wheel needs rebuilding as evidenced by an actual problem.

2- unless something like a crash or pothole prematurely finishes off a rim, spokes generally fatigue first. It might make sense to reuse spokes from a wheel that didn't see much life, but it definitely doesn't make sense to reuse spokes nearing the end of their life cycle.

3- as far as ERD's are concerned, 2mm shouldn't be make or break since it's only 1mm difference in spoke/nipple engagement. (difference between diameter and radius). But if for example the original spokes were coming to the tops of the nipples, another millimeter higher could be a deal breaker.

I also don't trust published ERD, and do all my spoke calculations based on my own measurements. Part of the issue is that some people, inclucing myself measure rims to the nipple seat (actual measurement). Others measure the ERD to the desired spoke height which is 2-3mm per side longer to account spoke reaching into the nipple's head. (expect mrrabbit to chime in here). IMO either way is OK as long as you use the data accordingly, but you need to know what you have, and that isn't always clear. There's 4-5mm difference in the two measurements, which is plenty enough to make any calculation useless (GIGO).

Spokes are certainly re-useable, but after 18 years and 10000km I would probably just throw them out and get whatever rim you want, rather than screwing around trying to match the ERD, and dealing with seized nipples.

On the other hand, as long as the brake track on your rims isn't dangerously thin I'd just keep riding them. It's not like old wheels "go bad" and suddenly stop working.

The 2mm is only 1 mm per side so a lace over should work well... I have relaced a good number of wheels on bikes I know have seen very few miles but after 10,000 miles I'd use new spokes with the new rims.

Ok, thanks everybody. I'm glad to hear that the ERD difference won't be a big problem... not so thrilled about the spoke issure brought up. I've never broken a spoke yet, and they are plain 14 gauge spokes, SS, with brass nipples, so they have been pretty sturdy. I'll take a look at new spokes, but my LBS charges a whoppin' $1 per spoke (for their cheapest) w/nipples - that instantly adds $64 to the $60 in new rims. I might just take my chances, here, and replace them as they break.

FBinNY, I've never put any really large stresses on the wheels, mostly gravel trails and roads, but the brake wear has taken its toll. The rims are dished in on the tracks and the rear one has a (kinda scary) bulge somewhat. I'm planning a 2 week tour, so I would really prefer if I didn't have to worry about the rims (which may defeat my spoke comment!).

I understand your desire to save dough by reusing the spokes, but it's false economy. By any measure these spokes have to be nearing the end of their service life, and the last thing you want to do is start a trip with spokes nearing the end of their life cycle. You're planning a trip and shouldn't sabotage yourself by pinching pennies here. Figure the added dough against the total trip budget, and the difference wheel problems can cause, and you'll see my point. Stay at cheaper motels a night or two to make up the added cost.

Also Spokes, especially plain gauge (which I very rarely use), shouldn't be $1.00 each, so consider buying them online. Get top end spokes DT, Wheelsmith or another proven SS spoke (butted is worth the difference) and do the job right. Or if the existing wheels don't seem in imminent danger, keep them for the trip and replace them afterward, when they go.

Damp, it sounds like your evaluation is correct. I let a rim get a little too worn once: http://home.comcast.net/~jeff_wills/...s/rites042.htm . Bad news if you're on a tour.

Let's see you want to R&R the rims but you're not worried about the spokes breaking. Really? If I was going on a two week tour, I would not want any mechanical issues hovering over my head even before the ride. Further once you start breaking spokes, the odds are you will probably loose quite a number of them. You either need to break down and buy the spokes/nipples or probably a better solution is to pick up $150-200 wheelset..

What hubs are you planning on re-using?

2 mm wont be an issue but i would put new spokes.

I'll vote contrarian and say to reuse the spokes - especially since they haven't given any problems in the past. I cycle under conditions that are kinder to the rims (very little rain and almost all on-road), so I get well over 50 kmiles before the brake track gets worn out. I've still reused spokes for two or three rims without any issues - so the spokes went for about 200 kmiles. At only 6 kmiles on the OP's spokes and none broken I wouldn't have any qualms about reusing them. (But I would carry a few spares if going on an extended tour.)

To keep all the spokes in the same position in the hub and minimize stresses it's easiest to tape the new rim alongside the old one with the valve holes aligned. Then move the spokes over to the new rim one at a time.

The 614.00mm number you are using for the Araya PX-35 is from Sutherland's which amounts to aiming for the top of a 10mm standard profile nipple. When aiming for the flat of a 12mm standard profile nipple, it comes out to 611.00mm.

The Rhyno Lite is listed at 612.00mm...my experience has been that oftentimes Sun is aiming in between...so it's 611.00-612.00mm

If the spokes that are currently in the wheel fall between the flat and slightly below the top of the nipples currently in use - I'd say you are good to go.

Re-use the spokes...especially if they have "DT", "W", "A" or cursive "P" on the heads, or "S A P" or "S A P I M" on the shank by the elbow.

Good Luck!

=8-)

This part isn't entirely clear, are the threads showing on the exposed spoke between rim/hub, or do you have visible threads penetrating beyond the nipple, into the rim?
If you have visible threads between rim and hub then you're really looking at a kinda marginal build, with less than available thread engagement. To rectify, you should be looking for a rim with, say 6-10 mm smaller ERD.

If you've got 2 mm protrusion beyond the nipple, into the rim, it's also verging on "exciting" depending on what nipples you have. The DT 12 mm that I'm most familiar with would be pretty darn close to bottoming out right about there. I wouldn't dare trying to rebuild such a wheel with a quoted identical ERD w/o verifying the measurement myself.
(Well, I might if it was a wide, single-wall rim.Then I'd be able to chuck in a washer underneath the nipple to gain a mm or so...) Preferably I'd look for a rim with 4-6 mm bigger ERD.

This is all assuming you're using the same point of ERD measurement on both current and future rim of course.

Whoppin?

No one has any concept of value anymore......when I look at what goes into making top quality spokes, I can't believe they only cost a buck! And what else can you buy for a dollar that lasts as long given its job?

BTW, your shop isn't making any money at $1 per spoke, if that makes you feel any better. I know. I own a shop.

Might want to pull the hub apart and check those cones for wear....wouldn't want to rebuild on a bad hub. Maybe an overhaul and fresh bearings, though you may be upset that bearings can cost up to, oh, a dime each. ;)

Shops in my area lately have been getting Sapim 14g's in bags of 500 for .19 apiece...and then turning around and selling them for 1.00 to 2.00 apiece depending upon the shop...

=8-)

Where, pray tell, are these shop getting these spokes?

Are they buying long and cutting down, or are they stocking thousands and thousands of spokes? If they are able to provide small quantities of any size on demand, then I'd say that's worth a premium price.

I know that to buy boxes of specific-length DT 2.0 spokes from a distributor, then selling at $1 is pretty much a loss leader.

J&B?
Wilson's?
QBP?
Raleigh?

...dunno...but of the several shops I've visited the last month or so...I'll see the same darn bags...and when I ask, "Oh, 95 bucks..."

If it's not a major distributor, then a small distributor is sitting on lots of 'em and is blowing them out...

=8-)

I agree that the 2 mm won't make much difference. And that 10,000 miles is getting a bit longer in tooth...although not excessive...for spokes but Dampcookie says the wheels have 10,000 kilometers which is a whole different distance. At 10k km, he's hardly broken them in yet.

A rim swap, without delacing the hub, is all that is called for.

Well, it ain't J&B or QBP......they don't do Sapim....

I'll have to check around.

10,000 miles is often a couple years and not a big deal. People have 100,000 - 300,000 miles on spokes.

If you find a buck a spoke excessive then they can be found for 50 cents (plus 10 cents for standard, brass nipples) here: http://www.excelsports.com/main.asp?...jor=1&minor=30

DT Competition DB spokes run 75 cents (plus 10 cents for standard, brass nipples): http://www.excelsports.com/main.asp?...jor=1&minor=30

Yes, check around. LBS in town sells DT/Wheelsmith straight gauge spokes for $0.50 with nipple. Any gauge, any length. They're not cut down but right out of the box. Butted spokes are about a buck each.

You might get them for less, if you buy the whole Box, 50 or 100 ct.
then you have the less than will build another wheel, leftovers ..

OK - so I'll try to clear some confusion. It's not an expensive wheelset, with standard "parallax" (Alivio level, I think) hubs. I've been pretty gentle to the wheelset, repacked the cones about 3 times so far, made sure everything was properly tightened and that the spokes were generally even in tension. I have done 1 full tour before on this wheelset, but I'm only 130lbs on a heavy day, and carry maybe 60 to 70 lbs for fully supported touring, so total weight bike+me+luggage would be ~ 230lbs. I've also done a few daytrips with ~30 lbs of gear.

The spokes have *never* given me a lick of trouble, even during/after these trips. I don't see why changing these as-yet problem-free spokes over to new rims should cause them to become more prone to breakage. So, I'll be siding with the contrarians mrrabbit and prathman. I've check my spokes, and they have "N" on the head - Chun Nuan Co. of Tiawan apparently. No surprise here though, as they came from a GT bike of the 90s....

@BikeWise1: I'll be camping for my trip, and generally low budgeting the whole thing. $1 per spoke IS whopping for me, no matter what. If spokes can't be had for less that $1-2m ea, it just galvanizes my resolve to re-use spokes. I may pick up 3 or so as spares, however.

Whether the spokes still have life left in them or not, this whole project hinges on being able to unscrew the nipples. Living in WI I have not had good luck disassembling old wheelsets. In most cases the nipples are so frozen they round off or the spokes break trying to remove them. At that point the remaining spokes get cut and I start with fresh ones.

Before doing too much planning I'd give each nipple one full turn loose to see if they will move or not.

I'm an importer of CN spokes...

If that "N" is dead center...then in all likelihood those are CN's. However if the "N" is off-center:


http://www.mrrabbit.net/docs/spokeheads/main.html


...then it's a "Z" and that is someone else.

It would appear that your wheel has had well-tensioned and high-tensioned spokes to begin with - and has been kept that way - and that helps ensure that they can be reused.


http://www.youtube.com/watch?v=hjdKJ...En_PcY4VLuZMgh


That's my video that includes a list of characteristics to consider when deciding whether or not to re-use spokes.


I've re-used entry and mid-range spokes in hundreds of wheels in the past - but it helps to be picky.

=8-)

The "N" on the spokes are dead centre, so its CN. I actually found your database in order to tell :P

The nipples on the spokes mostly seem to unscrew easily - but we'll see. Thanks for all the help guys.

not that this is definitive or anything, buy Cambria Bike Outfitters (uncle Cambria i call him) has DT straight gauge SS spokes for 40 cents each in many different lengths. but i have always reused my spokes if length is not an issue. maybe it's because i've only busted one spoke in about 30,000 miles and that was seventeen years ago.

just watch, now that i've said it, they'll be popping like William Shatner's shirt buttons!

I've had rims crack and one hub break but I've never had a spoke or a nipple break. If the spokes look good I'd reuse them. You could consider taking a couple of extra spokes with you on the trip.