I like to ride on tubeless wheels. Every car and road motorcycle on sale comes with tubeless wheels, rather than old-school inner tubes.
There’s a reason for that – it’s safer when the tyre is punctured. You are much more likely to suffer a slower deflation rather than a catastrophic, sudden blowout.
As such, it makes sense to apply this technology to older Vespa models rather than use split wheel rims and inner tubes, right?
Won’t that be a universally popular switch?
Problem #1: Tyre fitters hate you
The five widely positioned stud pattern of the Vespa 10-inch hub forces compromises in the design of a tubeless wheel for a classic Vespa.
An important part of the tubeless design is the “well’, which is a deep channel in the wheel rim that the tyre’s inner edge sits into while it is being fitted to the rim. Ideally, the well would be deep enough that the tyre bead – which is reinforced with wrapped steel wires – can be pushed over this lip without stretching or damaging it.
The wire represents the position of the tyre bead during the fitting process. You can see why the depth of the ‘well’ is important.
Compromise
Sadly, the position of the five wheel studs means that this well cannot be as deep as ideal, or the well would break through into the stud holes. This compromise means that fitting tyres to classic Vespa (and Lambretta) single-piece tubeless wheels is far more difficult than to dedicated tubeless wheels; such as those of the Vespa ET4 or GTS.
Many tyre fitting companies won’t touch 10” classic wheels. Often, their machines will not adjust down to 10” rims. Others have had bad experiences with single-piece 10-inch rims – such as ripping the rubber skirt on the edge of the tyre bead that provides the seal on the wheel rim. This can happen with ‘tight’ 10-inch tyres, even when a pro tyre fitter is using the correct machine. The result is a tyre that is either wrecked or will not seal against the rim without the use of bead sealer (black rubber paint used to seal leaks).
This is why customers with leprosy are more welcome at a car tyre fitter than those clutching single-piece 10” scooter wheels.
Problem #2: Getting old tyres off is even worse than getting new ones on
As much as getting a new tyre onto a new rim is a tricky but achievable task, getting old tyres off without scratching the rim is even trickier, because you must lever inside both the near and far side of the tyre to lift it up over the rim.
If you struggle to understand what I mean, look at our video at the end of the article showing tyres being removed at Rimini Lambretta Centre using their machine. It takes a lot of physical force to lever the tyre onto the machine’s ‘mounting head’; which can result in scratches on the rim if you aren’t careful. For this reason, RLC sometimes prefers to cut the wire beads of the tyre so it can be easily lifted off, especially on Vespa rims, which are more problematic than Lambretta ones.
Funnily enough, that’s the same method I suggested on SLUK’s old manual tyre fitting/removal video.
Problem 3: Some tyre models are tighter than others
As anyone experienced in this task will tell you, not all tyres are built the same. Some, like Nankangs, seem to be slightly larger on the internal diameter and can be fitted with tyre levers. Others, like Heidenau’s notoriously stiff K80SR, and some models from Mitas, seem tighter on the inside diameter. These are harder to fit without damaging the sealing lip on the edge of the tyre bead.
Aluminium wheels must be thicker where they fit over the stud for reasons of strength, but the depth of the nut on the BGM is revised.
Problem 4: Loose wheel issues
Vespa wheels can come loose if they aren’t fitted correctly, whether steel split rims or tubeless alloy wheels. I’ve seen plenty of steel wheels where the nuts have come loose and the rim has moved so much that it’s cut halfway through the studs and ovalised the holes in the wheel. 80% of the time, this is because the wheel nuts were not fastened correctly or tight enough. Occasionally, it’s because the rims were too thickly powder-coated and the coating has ‘sagged’ under the wheel nuts, allowing them to come loose.
There’s a simple solution: Check and, if necessary, re-tighten your wheel nuts often, and only use the correct nuts and washers.
When it comes to tubeless alloy wheels, the problem is slightly different. The thickness of aluminium under the wheel nut is greater than the thickness of two pressed steel split rims, so there is less stud thread poking through for the wheel nut to grip. Add a thick locking washer and there are even fewer threads for the nut to grip. Add in poorly made pattern hubs with shorter than original wheel studs made from cheese and now we are getting to a situation where the wheel nut is only holding on by a few rotations.
I personally have no issue with the supplied fitting method for SIP-type wheel rims of solid nuts, Nord-lock washers. If you torque the nuts as intended and re-torque them after 50 miles, then you should have no problem; however, this hasn’t stopped tubeless one-piece wheels from getting a reputation for coming loose in certain quarters of the internet.
One solution is to fit longer studs to the hub, but that’s quite a lot of work. It would be good if the standard fitting method could be tweaked to improve it slightly.
The BGM Superstrong wheel: is it any better?
The engineers at BGM studied the options for single-piece alloy wheel design and made a few very slight adjustments to try to solve the aforementioned problems. Their hands are somewhat tied by the fact that they still wanted their wheels to be fully homologated for legal road use, so the adjustments that they could make within the constraints of the Vespa hub design are quite small, but also quite useful…
Solution 1: Including a deeper well to ease fitting
Tyre fitting ‘should’ be easier if you can manage to include a deeper ‘well’ for the tyre bead to sit into during fitting. The BGM solution, similar to that on some other Lambretta wheels, is not to make the well perfectly concentric. Instead, the well is lowered and widened, but only in the five available positions between the wheel stud holes.
Both wheels are 2.10 width, but the BGM one is narrower overall, which should aid clearance to the clutch cover bolts on small frames in particular.
Solution 2: Other wheel dimensions are slightly tweaked to ease fitting
While both the SIP and BGM wheels are standard 2.10-inch width fitting, they are not identical. I measured a SIP rim at 73.3mm wide overall, but the BGM wheel was only 69.7mm wide. Reducing the distance the tyre must stretch from the well to the outer edge of the rim also makes fitting slightly easier.
The BGM rim also seems to be slightly narrower between the faces for the tyre beads, which means the tyre will sit with a slightly taller and more pointed profile.
Solution 3: BGM have tweaked the design of their BGM Sport tyres to ease fitting
The BGM Sport tyres fitted and removed for this video are also made by Heidenau, but to a specification determined by BGM, which is supposed to make them slightly easier to fit than other Heidenau models. They certainly seemed easier to fit than the K80SR, but are still tighter to fit than the Nankang we took off.
Solution 4: Maximising the thread contact to improve wheel security
BGM have made two subtle modifications to gain more thread contact between the wheel nuts and the hub studs.
Despite the BGM wheel having a thicker flange that the hub sits against (11mm versus 9mm), the flat-bottomed hole that the nut sits in is a little deeper. I measured 0.5mm extra thread coming through compared to a SIP rim.
On the right is the BGM washer system (Schnorr is a type of serrated domed Belleville washer). This is much thinner than the Nord-lock solution used by SIP (left).
The second modification is simple and anyone can do it, in order to access more thread for the nut. BGM chose to use 0.8 mm-thick Schnorr washers instead of 2.3 mm-thick Nord-lock.
I really like the security of Nord-lock stacked washers, but moving to a slimmer (and also good) Schnorr washer gains you approximately 1.5mm of thread.
In total, this means the nut is going on to the stud an extra 2mm, or in terms of this thread, more than one 1.5 extra rotations of the nut.
BGM specify that their nuts (also 12mm socket heads) are tightened to 20-22Nm and retightened if necessary after 50-100km.
Like any of these designs, it is vitally important to check and rebuild these wheels every time they are removed, following the instructions and using the same type of technical washers. For belt-and-braces security, you can also fit longer studs to the hub.
VIDEO: Fitting and removing tyres from the Superstrong rim
Verdict
The acid test of wheel design effectiveness was to mount and dismount the same tyre model onto both SIP and BGM wheels using the same tools and methods.
Fitting the BGM tyres was successful with the tyre machine in both cases without any great drama.
When it came to removing them, though, it took quite a lot of extra force on the tyre lever with the SIP wheel, which resulted in damage to the tyre, which would render it unfit to re-use. Bear in mind that you only normally want to remove a tyre when it is worn out or punctured anyway, so this is not really a problem. As Micky pointed out, he would normally have cut the bead to get a used tyre off anyway.
Removing the tyre from the BGM Superstrong rim was still not easy, and it was possible to still see marks in the rubber where the tyre lever had been used, but importantly, the tyre was still in good enough condition to be refitted and re-inflated.
As such, the difference in ease of fitting between the two wheels is small, but it is valuable. If it means that a tyre fitter can get a tyre onto and off your wheel without damaging it, then maybe they’ll hate you a little less.
Less tyre lever force was required to remove the BGM tyre from the BGM Superstrong wheel (bottom) which meant it was removed without any terminal damage.
As for the changes to the fitting method and construction to get more stud thread inside the nuts: I also think that every little bit helps; particularly given the cheesy studs of some pattern hub brands.
BGM Pro Superstrong wheels have gained German road-legal approval for use on the front, rear and even for use with a sidecar.
From my point of view, these changes do add up to a better tubeless wheel.
Words, pics and video: Sticky
Thanks to Micky at Rimini Lambretta Centre for help with the article.
Price and availability
BGM Pro Superstrong Vespa wheels retail for around €89. You can find them here in various colours, or at resellers of BGM parts.
3D-printed nut cover pointers allow you to visually check if any of your wheel nuts have come loose and moved out of line.
TOP TIPS FOR TUBELESS FITTING
It is commonly accepted that fitting tyres onto single-piece alloy tubeless wheels can be a bit of a game. Here are our tips for getting it done successfully:
- Choose tyres that are known to fit more easily. Ask around for suggestions.
- Do not try to fit cold tyres. The warmer you can get the tyres before fitting, the greater the inside diameter and the more pliable they are. Some scooter specialists warm tyres in front of a gas space heater to make them easier to fit.
- Use lots of good-quality tyre soap. The better everything is lubricated, the better.
- Ideally, get the tyres fitted by a specialist who is used to doing Vespa and Lambretta wheels. They should know all the tips and tricks and are less likely to scratch your rims using a machine than doing it all manually with tyre levers.
- Check any used wheel, (once the old tyre is off), for cracks and corrosion. Trapped moisture from water-based tyre soap, or wet compressors, will eventually eat into alloy rims. If the corrosion isn’t severe, then sanding and repainting the inside or using bead sealer should be enough to prevent slow leaks. Any cracked wheel, which has been overstrained with tyre levers, should be binned.
- Another option is using tubeless split rims. The Pinasco design, with a large O-ring to seal between the rim halves, does work, but note that home assembly is still quite involved, and it’s harder to change a tyre at the roadside than repairing a tubed wheel.
- If you would like a simple visual check that your wheel nuts are still tight then Darran and Danny from Boston scooter riders (amongst others) has produced a simple plastic pointer arrangement to push on over wheel nuts (both 12mm for tubeless and 13mm for normal M8 nuts. When they are all pointing in the same direction as you fitted them, then you know the nuts haven’t moved!
SLUK for tyres
Did you know that we can supply all leading brands of tyres? Many of the popular brands are listed in our shop, and you can ask us if you require something else or different sizes. Have a look here.
