Cracks in spoke bores, broken spokes

AlexRims - Cracks in spoke holes

The Taiwanese wheel manufacturer Alex Rimsthe Swiss company DT Swiss and the Spanish wheel manufacturer Rodi supply Stromer with rims.

Like Pirelli with blistering and cracking in the tires, AlexRims also has quality problems with the rims. After a certain period of use, my rear wheel rim had cracks in the spoke holes.

The cause could be the quality of the spoking or the basic quality of the rim itself. My rear wheel rim was replaced at a mileage of 8,800 km and re-spoked by my dealer. It has lasted for 21,300 km (as of Jan. 2025).

There are also isolated reports of corrosion around the valve. However, this problem is likely to occur mainly on electric vehicles in winter use, where salt leads to increased corrosion.

Guarantee? Stromer usually replaces affected rims under warranty.

Rodi - Cracks in spoke bores and broken spokes

Rims from the manufacturer Rodi have been appearing on Stromer bikes since around mid-2023. They can be recognized by the silver eyelet at the spoke holes and hubs from BLACKJACK.

The problem with cracks in the holes continues with Rodi. In addition, there is an increasing number of broken spokes - as reported in forums and FB groups can be read.

According to a post in the forum speedpedelcreview.com of July 4, 2024, the cause is still unclear.

Partial excerpts from the forum:

Stromer says that it is extremely difficult to find out the cause because, according to Stromer, an identical combination of parts used to cause no problems and is now suddenly causing problems...
In the event of structural problems, Stromer now has the wheels retuned by the dealer or an external wheel service. Several dealers are also said to have chosen different nipples and/or different spokes and therefore solved the problem. The ball is now in Stromer's court to ensure that the wheels are 100 % from the factory. (Source)

...Stromer has been discussing the solution for almost a year now, but has not even identified the actual cause, although it really can't be rocket science. And yes, wheels with broken spokes are exchanged for other wheels that are likely to break again. (Source)

Update August 18, 2024

Occasionally Reports that the ST7 also has broken spokes (1 | 2 | 3) should exist. DT Swiss rims are installed there. In the past, these were inconspicuous on the ST2S and ST5.

Solution?!

An analysis of the problems can be found in the speedpedelcreview.com forum. I quote here the translated version of the Wheel specialists Spaakshop in Belgium.

As a full-time wheel builder and specialist for heavy-duty wheels, I would like to comment here. I have re-spoked all Stromer wheels for a dozen bike stores in Belgium.

Not only Stromer, but also many other (speed pedelec) brands have problems with their bikes (e.g. R&M, Stromer, Klever, Opium, ...).

The reason is actually quite simple: saving on parts and quality.

Four causes:
1: Poor rims; the rims used are actually too light for the heavy use of speed pedelecs. In addition, the holes are not drilled at the right angle, especially for the large wheel motors.
2: Moderately straight 14G spokes. I only use the Sapim Strong with reinforcement on the spoke bend for this type of wheel construction, but still a flexible spoke that can take a beating. Stromer and others use normal straight 14G spokes.
3: The nipples are not secured, so that the nipples can come loose more easily than with secured nipples.
4: Quality of construction and control, the wheels are not stressed enough and there is a large fluctuation in spoke tension. This is known internally at Stromer and a solution is being worked on, or so the dealers promise.

For this, my partner RAD15 rims (a Dutch company specializing in short-run rims) has developed a special rim that is really very strong, the Storm33 with 33mm inner width, suitable for the wider tires of the High-Speeds. Their 'STROOP' model is specially drilled so that the angles of the rim holes match the spoke patterns of the STROmer and OPium engines (almost the same engines in terms of dimensions).

These rims have now been adopted by Opium as standard guarantee rims and are also used by Ellio and Santos, among others. We also build these wheels with Sapim Strong spokes and Sapim Secure Lock nipples, which are secured nipples that prevent loosening.

The combination of these components and the precise craftsmanship results in a super-strong combination, hundreds of which have already left the factory and none of which have ever come back with problems. These wheels are also mechanically loaded with up to 300 kg during the construction process to simulate the toughest driving conditions.

The problem for dealers is that Stromer still gives dealers the same rims and spokes under warranty, so the problem is really just postponed to several months/years later. Plus, of course, the refund is not enough for the dealers, so I have many customers (ie stores) who add this themselves because they know our wheels are 100 % fine and worry free. I even have one dealer who already includes re-spoking in his lease as part of the maintenance cost, simply because he knows the likelihood is high... (Source)

Price tag: New spokes with the STROOP rim and reinforced Sapim Strong spokes and nipples cost around € 233 incl. VAT. A new front wheel with DT Hybrid 350 hub, tubeless costs around € 330.

myStromer AG

If there is a problem with the Rodi rims, the dealer can submit a warranty claim to Stromer. Stromer will then replace the rim, have it re-spoked or reimburse the dealer a lump sum (as read) if he replaces the nipples/spokes himself. 

Customers report that this can happen again even after replacing the wheel or repairing the rim with individual or all spokes and nipples (Source 1 | 2 | 3).

Solution from retailers

Stromer dealers in Holland and Belgium, a large Stromer market, have apparently been looking for solutions themselves. They were able to locate the problem with the eyelets/spoke bore of the Rodi rim in combination with the nipples used, their length and the relatively large deflection angle of the spokes on the rear wheel. The problem could be further accentuated if the system weight is (too) high (max. 150 kg for 27.5″ models).

The solution of the aforementioned retailers is that longer Spoke nipple (14 mm instead of standard 12 mm) or Brass nipples can be used. Completely new spoking with replacement of all spokes does not seem to be necessary. If the defective spokes and all nipples are replaced with brass or aluminum nipples of 14mm, that seems to be enough, at least according to customer feedback.

Nipple recommendation

• SAPIM: Polyax brass Ø 2 mm | length=14 mm (e.g. for bike24.de)
• DT Swiss: DT Pro Head, Brass (12, 14 mm)

Spokes

If you also want to replace the spokes, you can use the DT Swiss Champion spokes 2.0 J-Bendblack, 188 mm. This fits the DT Swiss H612 rim, for example.

Alternative rims - 27.5″

Alternative rims are one way to solve the problem once and for all.

> See Chapter - 'Alternatives - 27.5″ rims' / (Spoke calculator / Spoking)