In praise of the humble mudflap

When I sang the praises of my SKS P45 Longboard full-length fender set back in the day, one noticeable feature they had were extra-long mudflaps. Their length looked comical at first, especially up front, where they were inches away from brushing the ground, but it was this exact length that made them so effective at keeping riders’ feet dry from standing water.

While Bino, my Dahon Vitesse folding bike, had SKS fenders of his own, he had no mudflaps – only molded plastic end plugs. Hence, I distinctly remember getting my feet wet from the spray off my front wheel as I first pedaled through the puddles along Paseo de Roxas Avenue at night.

Currently I’m on my second set of Longboards, after my original pair developed one too many cracks from road vibration. The mudflaps on those are still good, though, so I figured – why not reuse them on Bino?

As it turns out, it’s a very simple job. It does require a bit of drilling because of the mechanism SKS uses to mount the mudflap in place.

If you’re familiar with the clips used to hold plastic dashboard pieces to your car’s interior, SKS uses a variant of that. It’s essentially a fat two-part plastic rivet with its pointed end able to expand. You then drive a thinner plastic pin through the center of this rivet from behind, which will expand the pointed end prongs. Finally, a washer goes over the prongs to lock everything in place.

I broke out the pin vise from my plastic modeling toolkit and put on its biggest 3 mm drill bit. I then drilled into the plastic of Bino’s fenders. Even then, I had to make the hole a bit larger, scraping away more material by “drilling” with my hobby knife, to make sure the rivet fits into the hole. I’d say I made a 4 mm hole in the end.

The stock end plugs just slide off the end of the fender, so on went the mudflap.

The finished product is a front fender with increased utility and effectiveness. Less of the rear of the front tire is exposed, so there’s less potential for water spray to get flicked up from the road and onto your feet, the front derailleur, or the bottom bracket shell.

A cheap, cheerful, effective modification. Lovely!

Test ride impressions: Titanium – Lynskey Pro Cross

If you’ve read about my dream bike build, you already know that I have an affinity for titanium as a bike frame material – at least theoretically. At the recently held 2016 Philippine Bike Demo Day, I got the chance to put it to the test.

Lynskey Performance Designs Philippines was one of the distributors on hand. Considering their status as a boutique manufacturer, one that specializes in titanium, I found it mildly amusing that they had at least a dozen demonstrator bikes there – split between road and mountain. They even had a titanium fat bike in there.

Ralph and the crew were gracious enough to lend me their Pro Cross model. This is Lynskey’s cyclocross bike, one with some very unique design elements. Like old-school cross bikes, the Pro Cross routes all its cables externally with cable stops along the top tube, to facilitate carrying the bike on the shoulder in races. Also quite striking is the way the downtube twists along its length as it links the bottom bracket shell and the head tube, similar to the Helix road bike frame. Even with all this, however, the Pro Cross has a nod to practicality with complete mount points for fenders – even at the seatstay bridge and chainstay bridge.

Fortunately for my frame evaluation purposes, the Pro Cross demo bike was almost exactly the same size as Hyro, my Giant TCX SLR 2, and built up very similarly. Shimano’s fourth-tier Tiagra 4700 drivetrain handles power transmission with a 50/34T crank and what seems to be an 11-28T 10-speed cassette, all turned by Shimano’s Deore XT trail SPD pedals. Braking comes courtesy of TRP’s Spyre-C mechanical disc brake calipers – basically OEM Spyre models. Lightweight Axis disc brake wheels were shod with Clement’s LAS 33 mm file-tread tires.

As Lynskey primarily sells framesets only, the demo bike had a few mismatched parts – particularly the through-axle fork. Zertz elastomers give away its origin from a Specialized Roubaix. The 90 cm stem and saddle (can’t tell if it was a Romin or a Toupe, probably the latter) are also from the big S, atop a 27.2 mm-diameter seatpost. A compact drop handlebar completes the build kit.

Riding the bike around for twenty minutes, I had forgotten to ask Ralph to raise the saddle about 3 mm or so. Other than that, I paid careful attention to how the frame behaved.

The Lynskey Pro Cross demo bike. Basic size and geometry are very similar to my TCX, as was much of its build kit – great for a back-to-back comparison.

Immediately noticeable is just how smoother the ride is on the Pro Cross. The bike muffles surface irregularities and road acne better than my TCX, which tends to go for a purist, direct approach to road feel. At first I thought the comfort was down to the 33 mm Clement file-treads, but when I was told they were inflated to 60 psi, I knew the cushy ride was down to the frame itself.

Even with the plusher ride, however, the titanium bike is just as responsive to out-of-the-saddle efforts and climbing. It’s usefully stiff, and it helps that the bare Pro Cross is a little lighter than my commuter-kitted TCX. The Spyre-C brakes are as reliable as I’ve ever known them, despite some light squealing on this particular bike. Shift quality on Tiagra 4700 easily trumps my 105 5700 drivetrain – such is the lightness of effort needed to click through cogs and even chainrings.

There are a few details on the bike I’m not too keen on though. The top tube cable routing had some zip ties on it that snagged on my shorts. I’m also not a fan of the PF30 bottom bracket shell, about which I’ve heard too many horror stories to recommend. Finally, the seatstay-mounted rear brake caliper means mounting a rear rack is going to be a little more complicated.

There’s also the price. Despite greater efficiencies these days, titanium still isn’t cheap, and Lynskey’s rightfully built itself a reputation as a premium frame builder. With proper care, such a bike frame has the ability to outlive you, though, without the susceptibility to rust and the slight weight penalty that steel has.

I guess titanium is the stuff my bike frame dreams are made of. I’m glad to know it’s as good as it’s ballyhooed to be. Now how much is the going rate for a kidney these days?

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.