Reprise: Schwalbe Marathon Racer tires, 20″ x 1.5″

After four years, Bino was due for a change of footwear. Part of the reason why I stuck him on the turbo trainer at home was simply in anticipation of this fact.

The smaller 406 mm wheel size means greater rolling resistance and a faster overall wear rate, since the tires’ tread circumference makes more revolutions to cover a given distance compared to, say, Hyro‘s 622 mm. This was demonstrated in dramatic fashion by the sheer amount of rubber dust generated by my rear wheel whenever I used Bino on the turbo trainer.

Soon enough, it was also made crystal clear to me by how badly worn the rear tire got. At first the tread’s profile got flatter, with more of a pronounced step between the center and the shoulders. Later, the biased threads of the tire carcass were beginning to peek through, some of its carbon black oozing out and slipping on the turbo trainer. At this point, Bino sorely needed new rubber on his wheels and was definitely unsafe to ride on the road.

The outgoing Impac Streetpac 20″ x 1.75″ rear tire. You can see how much it’s flattened on its center tread.

The threads on the casing are starting to show due to the impregnated rubber having worn away. These aren’t roadworthy any more.

I paid a visit to Tryon in Makati and bought a pair of Schwalbe Marathon Racer tires. Bino’s outgoing front tire was also a Marathon Racer, but of a previous generation. The appearance of the sidewall logos, tread pattern, and other features were quite different between them, but they do share the Marathon series’ signature puncture protection.

FEATURES

  • 20″ x 1.5″ (ISO 40-406 mm); also available in 16″, 18″, 26″, and 700C wheel fitments
  • “Level 4 Raceguard” double-layer nylon puncture protection belt
  • “SpeedGrip” rubber compound for good handling
  • “LiteSkin” full-length reflective sidewall
  • Wire bead
  • 67 TPI casing
  • Maximum load rating: 75 kg per tire
  • Claimed weight: 340 g per tire
  • Pressure range: 55-85 psi

IMPRESSIONS

According to the marketing spiel, Schwalbe’s Marathon tires were specifically built for toughness and long service life, for applications ranging from touring to commuting. The “Racer” is so-called because it is the lightest model of the Marathon range – not really for its competition chops. Reinforcing the commuting bent, this was the first tire I heard of that had reflective sidewalls, although my original outgoing pair didn’t as they were of an older vintage.

The new Marathon Racers I got had beads that were ridiculously tight. This particular set was perhaps the toughest pair of tires I’d ever fitted onto my custom LitePro x Newson Sportec wheelset with 14 mm internal width, especially the one I mounted on the front wheel. Every time I used my bead jack to wrestle the tire up and over the rim, the wire bead would just walk itself right out of the bead hooks somewhere else. It was a frustrating ordeal that resulted in at least one tire lever getting sacrificed to the tire mounting gods. Eventually I ditched the bead jack and used every other trick in the book to finally seat this tire on Bino’s front wheel, after much cursing, the process leaving me a sweaty mess.

The “arrowhead” tread pattern on the current generation of Marathon Racer tires. Some people have already tried these tires on a turbo trainer and were put off by the noise due to the broken center tread.

Despite the deeply cut directional blocks on the tread, the Marathon Racer is strictly an on-road tire. Not that you’d want to take a folding bike like Bino to the trails anyway; it’s just not made to withstand that sort of riding. At 60 psi front and 70 psi rear, grip is fairly good, even in the wet. They lend themselves well to the deep lean angles that small-wheeled folding bikes excel in when cornering at speed, even on shiny concrete parking floors where traction isn’t so great compared to paved asphalt or concrete roads. They will relinquish grip quite quickly when cornering or braking on wet steel surfaces or wet leaves, though.

Normally I’d go into more of the minutiae of tires, but any discussion about the rolling resistance these tires offer is moot, at best. Neither is any discussion on ride comfort much of one. The 20″ wheel and tire combo is never really going to roll or cushion road acne as well as a 700C combo, and I don’t think this will change much with the kind of tire you mount. That said, since starting my indoor training in January, it’s no hardship for me to maintain an average pace of 17-20 km/h around my usual commute loop, so the Marathon Racers do seem pretty efficient.

These tires sure look good in profile. Most of it is down to the reflective stripe aping a gum sidewall.

Given how much swearing it took to fit these tires onto Bino’s wheels, the Marathon Racers should make up for all that gruntwork with their puncture resistance. For the most part, they do. Even on my old set, I had only ever one puncture.  Best to carry a beefy set of tire levers with you if you run these on your folding bike, not the ones that come with your multi-tool…and make sure your rim strips or rim tape is up to snuff to avoid punctures from inside.

With the air volume of an inner tube under it, like most other tires, it should stretch out and loosen up a bit over time, allowing for easier dismounting and remounting…I hope. Fingers crossed.

With my camera’s flash fired, the reflective sidewalls really pop as a couple of rings.

Finally we come to the reflective sidewalls. I think they’re nice, and any feature that boosts visibility to other road users, especially at night, is worth considering. They’re not perfect, however. The reflective stripe on mine doesn’t follow the circumference of the tire so well – it has a few wiggles along its length. I’d also prefer that Schwalbe broke these down into four long segments instead of making the tire one reflective hoop, because when the tires are in motion, the reflective segments are more eye-catching and convey a sense of the bike moving much better.

The outgoing Schwalbe Marathon Racer bought back in 2013 that served as Bino’s front tire. It’s worn, but the difference in tread pattern is still notable compared to the newer pair.

VERDICT

Schwalbe’s Marathon Racer tires, in a sense, are ideal for small-wheeled folding bikes such as Bromptons or Dahons, where wheel removal, tire dismounting, puncture repair, and tire remounting can be such bothersome procedures that any measures taken to avoid all that faff are worth your money. Virtually unknown in mid-2013, my old pair went for PhP1,300 apiece; with their popularity rising in the past few years and manufacture moving to Indonesia, they can now be found for PhP1,000 each.

Despite the “Racer” name, I don’t really consider these ideal for competitive use. They’re jack-of-all-trades tires; durable, grippy enough, resistant to punctures, and mid-pack in width. For really fast folding bike riders, Schwalbe’s diamond-patterned Durano or full-slick Kojak might be better options, while comfort seekers might be better served by their balloon-like two-inch-wide Big Apples. For ultimate puncture protection, everything else be damned, Schwalbe can sell you a Marathon Plus.

This is why you should regularly inspect your chain

Not too long ago, my chain broke just as I was beginning my ride. The outer plates on one of the links had given up, bending outward in dramatic fashion.

This was a first for me.

Driving a joining pin into a Shimano CN-HG54 10-speed chain using a multi-tool’s chain breaker.

These days, there are many, many resources online that can help you with chain repair and get you going, assuming you have the right tools and supplies on hand. Specifically, you’ll need a multi-tool with a chain breaker, plus either a spare joining pin (for Shimano or Campagnolo chains) or a master link (for SRAM, KMC, Taya and Wippermann chains).

I carry these in my saddlebag, and I know how to use them, so the only inconvenience for me was leaving about ten minutes later than planned…plus dirty, greasy fingers from handling the chain. My KMC 10-speed master links had some rust on them, but were still very usable, and so I replaced the busted outer plates with one of the master links and made it to my destination safely.

That should have been the end of it. Or was it?

My trusty Park Tool CC-3.2 chain checker, here indicating that the chain has not yet worn down 0.75%. A cheap, must-have tool.

A few days later, I took out my Park Tool CC-3.2 chain checker and used it on the chain. The 0.5% end fell straight through the links, indicating 0.5% wear. The 0.75% end didn’t, though. Okay, I told myself, I should stay on the conservative side and look for a replacement chain, but no hurries.

I took a closer look at the chain though and found this.

Apparently there were more links on my chain with broken outer plates. These were ticking time bombs. There’s no way of telling when these outer plates would finally let go and lead to another chain failure event.

I replaced the chain straight away.

A pair of outer plates and chain rivets from my KMC X10EL chain. Note the broken outer plate. There were more of these.

Park Tool recently released a few videos on its YouTube channel on chains, sizing, repair, and replacement procedures. It stressed that in case of chain breakage, you could always repair it the same way I did. However, that broken chain must be replaced as soon as possible.

Well, the broken outer plates all over my repaired chain are one possible reason why. Even at 0.5% wear, which for 10-speed chains indicates a bit of life left, my chain clearly shouldn’t be ridden any longer. These broken links are what you should take particular notice of on your chain – we all know what they say about it only being as strong as its weakest link.

Always keep a spare chain at home to match your drivetrain, at least as long as your current chain’s length. As long as the packaging is unopened, you won’t need to worry about it rusting or corroding, as it comes coated from the factory in a grease-like lubricant for storage.

2013 Dahon Vitesse: Main frame hinge parts disassembly and replacement

WARNING: This post is purely for demonstration purposes only. If you decide to follow its instructions to service your own Dahon folding bicycle, proceed at your own risk. I will not be liable for any injury or warranty loss that may arise from you following these instructions.

Previously I wrote about how loose Bino had gotten at his Achilles’ heel, his main frame hinge latch. The last time this happened, I brought him to Junni Industries in Quezon City for repairs. This time, with more mechanical know-how and hoping to save time, I decided to do it by myself.

Noting the many similarities of the Dahon Vitesse to cheaper variants of Tern’s Link folding bikes, and their shared manufacturer, Mobility Holdings Inc., I got Tern’s FBL Hinge Parts set for the 2013 Link C7 from Thorusa.

TOOLS AND SUPPLIES NEEDED

  • Tern Link C7 FBL Hinge Parts set (2013-up)
  • Hex keys: 2 mm, 5 mm
  • Torque wrench
  • Pliers or Philips screwdriver
  • Adjustable wrench or 6 mm open wrench
  • Medium-strength thread locker, e.g. Loctite 242

Open the frame hinge as normal. Fold the main frame tube 90 degrees to expose all the inner parts, as folding it all the way hides them.

Ideally, you would strip the frame first of all its components, especially the cranks and cabling. If that’s not possible, you will need to find a way of supporting the bike even with its main frame tube folded up. I used my Minoura DS-30AL display stand to support the heavier rear half of the bike.

THE SURGERY

Tension adjustment bar attached to the tension pin.

The first thing that has to go is the hexagonal bar that serves as the main latch lever’s tension adjustment. I call this the tension adjustment bar. Like a typical barrel adjuster, you increase tension by backing it out and turning it counter-clockwise. Back it all the way out with your adjustable wrench or 6 mm open wrench until its threaded end separates from the main latch lever’s security pin.

Main latch lever security pin.

You can pull the main latch lever security pin up and out once free.

Tension pin.

Once disengaged from the main latch lever, remove its other end, by either undoing a screw or removing a circlip with pliers, and pull it out. This also releases the tension pin that sits on the front half of the frame tube. Pull and slide it downwards; it should still have some grease on it.

Removing the top hinge pin bolt.

Removing the bottom hinge pin bolt.

The two hinge pin bolts.

At this point, the only thing remaining of the hinge assembly that connects to the front frame tube is the hinge pin bolts – there are two of them. Take your 5 mm hex key and undo them both. Note that the lower of the two hinge pin bolts has a plastic bushing which the front frame tube rotates on; remove this as well. Removing the hinge pin bolts results in the frame separating into its front and rear halves.

The separated front and rear halves of the Vitesse’s main frame tube.

Once the two halves of the frame are separated, you can access the plastic bushing, shown here held by my pliers. It fits into a recess in the lower pivot.

The final component that may need replacement is the main latch lever itself. It’s held in place by a grub screw (i.e. a screw with no obvious head) on the drive side. You should be able to undo both of these with your 2 mm hex key.

Removing the grub screw that secures the main latch lever and its pin axle.

Grub screw removed.

The main latch lever spins on a really long axle, so slide this downward to free it. You can use a 3.5 mm bolt to screw into the axle to make it easier to extract. I didn’t have one, and my main latch lever was in good condition, so I left it alone.

Clockwise from left: latch tension pin, grub screw, main lever security pin, tension adjustment rod, tension adjustment rod securing screw, hinge pin bolts, 3 mm hex wrench, plastic bushing

At this point the Vitesse’s main frame hinge assembly is fully disassembled. Take the Tern FBL Joint Repair Kit and replace any parts as necessary. In my experience, I’ve had the tension pin bend and the main latch lever crack before.

When reassembling, take note that the following parts should have medium-strength blue thread locker applied to them from the factory:

  • Hinge pin bolt x 2
  • Grub screw
  • Tension adjustment bar

If this is missing from their threads, reapply. This will prevent them from walking out of thread engagement due to vibration while riding.

Once fully reassembled, make sure to readjust the tension adjustment bar with your open wrench. As per Tern’s Owner Briefing video, when properly adjusted, the main frame latch should open with two or three fingers, and close with the palm of your hand.

POST-OPERATION NOTES

My main concern prior to the repair was that the hexagonal tension adjustment bar had run out of usable screw thread, and it may have been due to the hinge pins becoming bad. Tightening any more resulted in the bar separating.

As it turns out, the adjustment bar used when it was last repaired as a smidge too short, by about 5 cm. Not only that, it was secured to the tension pin by a screw, instead of a circlip on both the original hinge parts and the Tern FBL hinge parts set. This allows a bit more slack, and ultimately more scope for adjustment, without the tension adjustment bar releasing from the main latch lever due to running out of screw thread.

A photo of Bino upon acquisition. Note the tension adjustment bar. It’s anchored to the tension pin via a circlip. The replacement part that Junni Industries used was 5 cm shorter overall and anchored by a screw.

With more scope for tension adjustment, the whole bike becomes much stiffer. Now it actually takes a bit of effort to shut the main latch lever flush with the main frame tube, which is very reassuring. Of course, it will never be quite as solid as Hyro, my cyclocross bike with its traditional diamond frame, but it’s sufficiently stiff and no longer worrisome when riding.

Adjust the tension of the main frame hinge lever with an adjustable wrench or 6 mm open wrench. As per Tern’s instructions, it should require the force of the palm of your hand to close, and three fingers to open.

As with many DIY repairs, I have a newfound appreciation of the engineering that went here – the original reason why folding bicycles appealed to me. However, I am also more cognizant of the limitations of the design, and so Bino will most likely lead a more genteel riding life with me going forward.