Cycling UK Forum

What's the catch with these rims:

https://www.ebay.co.uk/itm/REDUCED-PAIR ... KfN2QHE0xw

The description says they lace up the same way as conventional rims, but what about spoke lengths or any other pitfalls..??

Edit: to replace the current Sputniks on an all weather utility bike which tend to wear out too quickly.

they build up using two spoke lengths if you are moderately fussy, one spoke length if you are not.

As rims they are nothing special and because the spokes are not distributed at the rim evenly, they may not true up as well if they have a slight kink; you can't move a piece of unsupported rim.

You can work out the exact correct spoke lengths using fractional crossings. It varies with the hub and crossing value but often they are at least 2mm different from one another. Building with the different lengths is a slight faff, and you have the expense of the spokes, but down the line re-rimming is no worse than any other wheel.

Sputniks are fairly cheap and if they wear out too fast then a different brake block/use strategy might fix it? It is almost guaranteed that the rims you are thinking of buying have thinner braking surfaces.

cheers

Thanks for that Brucey, all valid points. It probably is the cheap brake blocks as I have been making a conscious effort to prioritize front wheel braking on this latest set of Sputniks. However the rear is nearly shot after about 6000 miles (which I suppose is not too bad). Perhaps I'll try another Sputnik and some higher quality pads, at least I can re-use the existing spokes.

Some more info; I call them 'cluster spoke rims' although they may have another formal name, I've never heard or used it.

There are two common types which I call X-cluster and W-cluster (there may be others too). In X-cluster rims the valve hole is between clusters and in W rims it is in the middle of the cluster. In the photos below the cluster rims are compared with a standard rim and the fractional crossings (for a nominal x3 pattern) are indicated.





X cluster (valve hole between clusters) (x3 = x2.625 and x2.875) or W cluster (valve hole inside cluster) (x3 = 3.125 and x2.875)

You can calculate spoke lengths accurately using any calculator which supports fractional crossing values, e.g. EDD

Example; 60dia 28offset hub 600 rim 36x3 = 286.3mm, x3.125 = 287.5mm, x2.875 = 285.2mm, x2.625 = 282.9mm

different hub diameters give different discrepancies in spoke length. There are also solutions using +1 or -1 crossings etc.

[edit; NB if the holes are spaced differently in the rim then the fractional crossing values will also be vary]

cheers

If being really fussy, for a rear wheel build (cassette hub) then theoretically you would require 4 different lengths?

yep, although it might well resolve to just three once you had done the sums.

cheers

I am still interested in building up a couple of these rims as they are reasonably cheap and it's all good experience.

The only confusion is regarding the spoke lengths for X cluster rims.



Using the fractional crossings of 2.875 for the inner pair of spokes, and 2.625 for the outer pair results in the inner pair being longer. I don't have a built up wheel to hand for visual check but going by slightly blurry images on the eBay site it looks like the outer pair should be a little longer. There's not much in it, maximum 3mm for a rear wheel build but this would obviously be magnified if the wrong spokes were placed in the wrong holes!!

Any thoughts, cheers

What are the advantages of cluster spoke wheels?

SimonCelsa wrote:I am still interested in building up a couple of these rims as they are reasonably cheap and it's all good experience.

The only confusion is regarding the spoke lengths for X cluster rims.....

Any thoughts....

If the drilling pattern is as per the picture then those are the correct crossing values to give the correct spoke lengths for a x3 build. If the pattern is different (either in basic layout or exact spacing) then they won't be.

In the photos I have placed a standard rim adjacent to the cluster drilled rim so that it is easy to judge whether the pattern in an unknown rim is the same or not.

FWIW if you are going to build with these rims and you expect to wear the rims out, it makes sense to buy spare ones now, because there is no guarantee that these rims will continue to be available. If they are no longer available and you don't have any spares then when the wheel is rebuilt then you will have to buy new spokes as well as a new rim, and between the extra time and extra cost of rebuild there is no advantage to using these rims regardless of price.

If you are not sure about what you are doing then it will probably cost you a set of spokes at least, and if it goes really wrong then the rims will be a dead loss too.

cheers

Cyril Haearn wrote:What are the advantages of cluster spoke wheels?

in practical terms none.

cheers

Disadvantages are obvious
Minusminus?

Cyril Haearn wrote:Disadvantages are obvious

some are, some aren't.

cheers

Thanks for all the info.

Yes, I've gone ahead and bought a pair for £15 so not the end of the World if I totally pringle one for practice!!

The plan is to build up one into a rear wheel with the cheapish Tiagra hubs on the SJS site and then keep one rim for spare. I know it would be easier to try out a front wheel build first but my front rims seem to last forever. Spokes are still cheap at 'cyclebasket'.

See how it all pans out. Again, thanks for the helpful advice, much appreciated.

Hi,
Fashion init.
A bit like wired twisted and tied spokes

Unfortunately my fashion sense is usually 20 years behind the times!

What are the advantages of cluster spoke wheels?

The only advantage I have heard of is that the staggered gap makes it easier to get a D-lock or thick cable lock through......hardly a major benefit but for a hack bike I think the price is right and if I get a couple of years out of 2 rims I'll be happy.