Stainless rims.

[john998]

Hello,
While cleaning the solo noticed breaks in the paint on the rear rim. As the tyre was coming off for a replacement I could get a better look see.
Have found tree dimples with cracks running from the spoke hole down the dimple and almost to the bead area. These rims have done 25K and this one has already had new
non stainless spokes as I got sick of replacing stainless broken ones. Have had a good look at the matching front rim and it looks OK.
Next thought is do I replace it with another stainless rim? The first picture shows the manufacturer.

Regards John.

 

[davidd]

John,

I would say that you are running your spokes too loose. Loose spokes can cause rim failure. If you were breaking SS spokes, you were definitely running them too loose. I run Buchanan SS spokes and in several decades I have never broken a spoke, even after crashes. I run them between 80-100 inch/lbs. This is high enough to pull a nipple through the rim if you are not careful about equalizing as you run up the nipples.

If you are not using a spoke torque wrench, then you are just guessing, which is fine if you are having good luck, but most guessing yeilds somewhere between 20-25 inch/lbs. I would use all steel components if you choose to run your spokes loose as steel is so much more forgiving.

I have only run steel and aluminum rims and I have no experience with SS rims.

Good catch! It is one of the reasons I wipe down the bike.

David

 

[john998]

Hello David, and thanks for that. The man that built the stainless wheel was I think a better painter than wheel builder. When rebuilt with galvanized spokes the man that did the work was the top man in the area, he did many wheels for the trials boys. Perhaps the damage was already done. Have replaced it with a spare wheel with Boriani alloy rim left over from my racing days. These wheels have done much service without any problems.
The only wheels I have built where for the outfit, 15" Akront rims these have been fine so far. Being small diameter they looked easier to build that a 18 or 19", i would think that a push bike wheel would be the most difficult to build.
It might be worth other people with stainless rims to inspect them.
Regards John.

 

[vincenttwin]

Make certain when you put the brake hubs onto the center spoke hub , that the brake hubs are not pressing the spoke ends ,mine was and I was breaking spokes, The new brakes were hitting the heads of the spokes and not allowing them to seat correctly , I put a couple of Peter Barkers shims in between the brakes and spoke hubs and all is fine now.
I would say the reason your wheel rim cracked is that you were only running on half your spokes and the due to the strain on the spokes they broke or pulled on the rim spoke hole.
I would guess just before you started to break spokes you changed the brakes or the spoke hubs.
cheers
Peter
I know only because I have done this myself.

 

[john998]

Hello Peter, Had a good look at the clearances at the back of the drum and found no problem. I suspect that it is replacement/ modern drums that are a different shape. All my wheels have no problem in that respect.
Have stripped the damaged wheel, the tension on the the spokes felt OK, the cracks are two on one side one on the other. Just concerned that this could occur to someone else with these rims.
Regards John.

 

[davidd]

John,

I have a feeling that you would be better off not mixing materials. I would consider changing to steel or alloy rims. This is the wrench I have used for the past twenty years. I had them set it at 80, but the Vincent wheels will take 100. This is for new rims only. Replated rims are thinned around the spoke holes so they will not hold a tight spoke.

http://www.fasstco.com/shop/spoke-torque-wrench

David

 

[john998]

Stainless rims

Hello All, Just a thought how do the spoke heads hit the bake drum when the out board spokes stick out so much?
On my wheels it would appear impossible. Regards John.

 

[A_HRD]

Hello All, Just a thought how do the spoke heads hit the bake drum when the out board spokes stick out so much?
On my wheels it would appear impossible. Regards John.

John,
There are 3 potential problems with Vincent spokes laced in the standard(?) 'Cross Four' pattern. Especially where new components are used.

1. To answer your question above, it is (or can be) the outboard ELBOWS of the spokes that can touch or press on the drums. This is because stainless spokes (especially 8G) need a slightly bigger radius than original steel ones meaning the length from elbow to spoke-head is longer. Also, some repro drums had insufficient clearance at this position.

2. Secondly, spoke heads are now of much larger diameter than ever they used to be. This means that when the next spoke along passes near the outboard spoke-head of the first spoke, it can touch the head and pivot around same - causing a permanent bend and hence high stress. I lightly grind a small flat on the perimeter of each relevant spoke head - 10 per side. For a photo, see my MPH article which I believe was in the Oct 07 edition.

3. Repro spoke-flanges sometimes have insufficient angle of "dishing". This means that as each outboard spoke passes over the outer periphery of the spoke-flange, it can bend around the periphery; more stress - especially with the back wheel where the hub is much wider. I have been known to lightly machine the outboard edge of spoke flanges to provide clearance here. Its usually only a few thou - but it's a very important few thou.

Wheel-building is not really the black art that many people believe it is. The first one you do might take you a couple of days, the next one day, the next half a day and so on. But it is essential not to rush the job and to ensure that each spoke has an unimpeded run from spoke-flange to rim.

If you still choose to use the services of a wheel-builder that's fine; but do use a thin feeler gauge and spend 5 minutes checking for the above problems. The builder takes about 25 minutes to build and true a wheel - and it won't occur to him to do the above checks on Vincent wheels. Don't ask me how I know.

Cheers,

Peter B
Bristol, UK.

 

[john998]

Hello,
Just rebuilding this wheel with a new stainless rim. An oddity appeared in that the old spokes are in two different lengths.
After much pondering this is because the flanges have different bolt hole/spoke hole alignment. This makes building the wheel more of an thinking exercise.
Also with the new rim the short spokes are OK but the long spokes are rather short, this must have something to do with the
new rim drilling.
Have now checked the stainless spokes that I replaced as they kept breaking, these were in the wheel originally, they are all the same length 8 1/8"
Now I am confused suggestions please.
Regards John.

 

[vibrac]

I This is the wrench I have used for the past twenty years. .

http://www.fasstco.com/shop/spoke-torque-wrench

David

WoW! with postage from USA its a lot of money, I shall search for a UK supplier