The Golden Wrench

A blog about bicycle repair and maintenance by the mechanics at Freewheel Bike.

Monday, November 22, 2010

Replacement Studs for Studded Tires

Studded tires make a world of difference when the streets are coated in a layer of glare ice.  The studs, typically made of tungsten carbide, are small thumbtack-shaped pieces of metal that are held into the tire by their wider base end.  It's very common to lose a stud or two from time to time, but they are easy to replace.  Unfortunately, only some manufacturers offer replacement studs for sale.  Let's see how close of a fit the available studs are to several other manufacturers' studs:



Nokian studs
Probably the most common replacement stud available is the Nokian pointed-tip stud.  These studs are found on the Nokian Extreme models, and are only slightly different from the domed-tip studs found on most of the rest of Nokian's tires (the A10, W106, Mount & Ground, etc.)  All of the readily-available Nokian studs are the pointed tip variety.  There is almost zero difference in the dimensions of these two studs.
  • Material: carbide
  • Tip shape: pointed or slightly domed versions
  • Overall height: 5.8mm (pointed), and 5.5mm (domed)
  • Base height: 1.0mm
  • Base diameter: 6.5mm
  • Shaft diameter: 3.4mm
  • Tip diameter: 2.0mm
Schwalbe studs
Schwalbe's Marathon Winter tires are available in a number of different sizes, and all use the same type of stud.  Unfortunately, Schwalbe replacement studs are not normally available.  Fortunately, Nokian replacement studs are a perfect fit.
  • Material: carbide
  • Tip shape: flat
  • Overall height: 5.5mm
  • Base height: 1.0mm
  • Base diameter: 6.3mm
  • Shaft diameter: 3.4mm
  • Tip diameter: 2.0mm
Continental studs
The stud measured here was borrowed from a Continental Spike Claw 240 tire.  Continental replacement studs are not normally available, but Nokian replacement studs are a perfect fit.

  • Material: carbide
  • Tip shape: slightly domed
  • Overall height: 5.5mm
  • Base height: 1.0mm
  • Base diameter: 6.4mm
  • Shaft diameter: 3.4mm
  • Tip diameter: 1.9mm
Innova studs
Innova tires are usually quite a bit less expensive than other studded tires, but beware that Innova uses an inferior material for their studs.  Instead of tungsten carbide, Innova's studs are made from plain old mild steel.  While they are less expensive to produce, steel is significantly softer than your average pavement surface, and the studs literally wear down over time if ridden on bare pavement.   The expected lifespan for these studs can be less than one season in many cases.  Innova studs are readily available, but are not a good choice for replacing missing carbide studs from other manufacturers for durability reasons.  Despite the slightly different dimensions, these studs should be close enough in size to be interchangeable with all of the other studs measured here.

  • Material: mild steel
  • Tip shape: irregular, rounded-off tip
  • Overall height: 5.4mm
  • Base height: 1.1mm
  • Base diameter: 6.9mm
  • Shaft diameter: 3.8mm
  • Tip diameter: 2.5mm

The bottom line is that all five of these studs should be interchangeable with one another.  If you're missing a few studs from your Schwalbe or Continental tires, the readily-available Nokian studs should be a perfect replacement.

The only major stud not available for measurement were those used in Kenda Klondike studded tires.  If a Kenda stud comes my way, I'll add it to the list.

15 comments:

  1. Thanks....just the info I needed. I am going to add a few studs to my Continental Ice Spike 120's.

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  2. Question! Are the carbide studs corrosion resistant/proof? If not, what are the physical properties of tungsten corrosion. I have a set of Nokian Hakkapeliittas with what appears to have rust forming on the studs. Which draws another question... has Nokian always used tungsten carbide studs (opposed to steel)?

    P.s. We fellow mechanics really appreciate this blog. I try to check it daily.

    Thanks in advance.

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  3. Hi Vincent! Thanks for writing in.

    The actual carbide portion of the stud (the tip which contacts the ground) should not be capable of rusting because they contain no iron. Rust is oxidized iron, or iron oxide. Without iron, you're missing a key ingredient.

    That's not to say tungsten carbide is immune from corrosion of any sort. It can apparently be attacked by sulfur, chlorine, chlorides, and acids. These are all things very unlikely to come into contact with your studded tires, so you should have nothing to worry about. These materials affect the binder agent, which is often cobalt, and can theoretically cause the carbide to crumble with enough or bad enough exposure.

    Most studs use plain old steel for the carrier/holder portion (which looks like a nail head; the carbide pin protrudes from the narrower end). This steel contains plenty of iron, and is more than happy to oxidize when repeatedly bathed in the salty ice water found on our streets and trails in the winter.

    You'll almost always see surface rust on the stud carriers of used tires, but nothing on the carbide pins. The amount and speed of the rusting is so minor that it can be ignored. Some people put a drop of light lube or oil on each stud in the spring to give them an oily coating, but this might make it easier for studs to be torn out of their sockets in the tire. Rinsing your tires off with water and letting them dry thoroughly before spring storage should be all you need.

    For more reading on carbide corrosion, here's where I got my information:
    http://www.practicalmachinist.com/vb/general-archive/does-carbide-rust-81308/

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  4. I have one Nokian w106 and one Innova that looks just like the Nokian. In one season the Innova tire's studs have totally ground down and I really don't trust the tire on ice now. Could I rip the studs out of the Innova tire and replace them with Nokian studs? Will they fit and stay in the Innova tire? Any ideas?
    Thanks,
    Josh

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  5. Hi Josh,

    The short answer:
    I'll bet it would work just fine.

    The long answer:
    The base of an Innova stud is slightly larger than the base of a Nokian stud, but only by 0.1mm in thickness and 0.4mm in diameter. This means that a Nokian stud will be a slightly looser fit in the sockets molded into the Innova tire, but I don't think it's a big enough different to worry about.

    If you end up trying it, we'd love to hear how it goes.

    -Karl

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  6. Question -

    Are the 'holes' the studs fit into specially molded to take the foot or base of the stud? Or are they just simple holes and pressure keeps them in?

    The reason I ask - can one use the Nokian replacement studs to add some teeth to another set of non studded tires? Will a simple drill to proper depth work?

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  7. Mike, unfortunately for your scenario, the sockets in the tire are not just a cylindrical hole. They have a wider pocket at the bottom corresponding to the shape of the stud with the flared portion at the base.

    Unless you could devise a way to cut a hole with that shape, I really doubt studs would stay put in your tire. Also, rubber generally needs to be cut; a drill bit like used with wood or metal would just mangle it and not cut a clean hole.

    I've often wished that boot manufacturers would mold these pockets into the soles of winter footwear so studs could be added by the user if desired. Maybe I'll get rich on that idea... Well, probably not.

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  8. How do you squeeze the new studs in to the very tight hole? I know there is a special tool, but how do you do it without one??
    cheers.....

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  9. ah! Found a way now: take a tight grip with narrow-nose pliers, dip in washing up liquid and push directly into the hole with considerable force :)

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  10. Awesome Post! Thanks for the info!

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  11. I discovered that using the Nokian tool is nice. I keep the tire fully inflated and push the stud directly into the hole, wiggling around a bit. I didn't need any lube.

    Schwalbe studs are now available:
    http://www.schwalbetires.com/accessories/studs
    The prices seem off. Bike shop people can order them by the dozen from Schwalbe NA for about $12 retail.

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  12. Schwalbe replacement studs are now available for the ice spiker and the ice spiker pro. Contact Schalbe at Schwalbe North America
    Head Office
    105 - 536 Herald Street
    Victoria, BC V8W 1S6
    Canada

    Toll Free: 1-888-700-5860
    Tel: (250) 598-0397
    Fax: (250) 598-2018

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  13. Continental and Nokian studded tires actually come from the same factory in Lieksa, Finland, so there's a good chance that the studs are not just similar, but the exact same ones. :)

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  14. Hi From UK.

    I sent an email to Schwalbe UK and let them know that I had lost about 8 studs from my Marathon Winter Tyres.

    So they sent me 90 studs in the post for free.

    Fantastic Service from Schwalbe in the UK

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  15. Hmm, I wish I'd seen Anonymous from UK's Dec. 7th post and given that a try -- I lost 9 studs last winter in a pair of Schwalbe MWs and would have lost 3 more if I hadn't noticed & saved them.

    FYI, QBP's "45 North" brand sells carbide-in-aluminum replacement studs that look just like the Nokian pointy studs and are basically the same size. Most online merchants seem to be out of Nokians right now, so the 45Nrth set may be a good alternative.

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