For most of Bino’s first year with me, I was busying myself with simply building my own cycling fitness. I had been off the saddle for a very long time, and I was essentially playing catch-up.
After a while, though, I started to see some limitations. The 52x28T stock gearing, paired with the small wheels, wasn’t particularly friendly on climbs, and Bino’s folding frame simply lacks the stiffness to lend itself to out-of-saddle efforts. Conversely, while not as important as the low end, the 52x14T top end set a limit of 42 km/h on a flat sprint. While it’s very taxing on both my cardiovascular fitness and Bino’s frame to push to that speed, I was getting to the point where I was maintaining higher cruising and average speeds.
I decided to upgrade the little Dahon into a 10-speed bike – hence turning its “D7” moniker into a “T10.” The heart of the upgrade revolved around a Shimano Tiagra cassette, expanding the total gear range from 14-28T to 12-30T. This added two teeth in both directions, theoretically improving both maximum speed and climbing.
However, Bino was a 7-speed bike based on a screw-on freewheel, and there was simply no way of mounting the new 10-speed cassette without at least replacing the rear hub for one with a proper splined freehub unit. So, apart from all the drivetrain-specific parts, I invested in a new custom wheelset too, as required by the planned upgrade.
Tryon in Makati is more than just a regular haunt of fixed-gear cyclists. The long-lived bike shop is also known for its wheel builders, some of which have achieved urban legend status due to the quality of their work.
It was here that I had the wheels built. I specified a set of LitePro hubs and quick release skewers, silver Newson Sportec 406 mm rims with a deeper rim section, and black Newson Sportec spokes and nipples. Rene, one of the younger mechanics, took all of these components and laced them into a wheelset.
The only change I requested was to drill out the Presta valve hole for a larger Schrader valve, since Schrader-valve inner tubes for folding bikes are easier to procure here.
With the wheelset built, I can now install the Tiagra CS-4600 10-speed cassette. For this 12-30T unit, most of the cogs are pinned to a central spider or carrier. The only loose parts are the lock ring, the last three cogs (12, 13 and 14T), and a spacer that goes between the 14T and 15T cogs. The two smallest cogs have built-in spacers.
It’s not the lightest cassette around, but it’s got generous range. At the time, this was the widest-range option for Shimano’s 10-speed road bike groupsets. Presently, though, it’s been eclipsed by Tiagra 4700, which offers the option of a whopping 34T max cog.
Next time I will discuss the rest of the rear drivetrain parts – the rear derailleur, shifter and chain.
the accidental randonneur 
As a fellow budget-Dahon upgrader, may I suggest that a custom cassette would have met your needs better, and more cheaply? 2 weeks ago, I too bought a 7-speed with a 14-28 freehweel (10-year-old craigslist Eco 3, in my case), and realized that in hilly Vancouver I needed more range. I now have a 7-speed 11-13-15-18-21-26-34t (31-95″); 309% range, rather than your 250% – without needing a new shifter. I got a new 7-speed freehub wheel at a firesale price, presumably because it’s seen as obsolete – and built my wide-range cassette using spacers & the 5 lower cogs from a 7-spd 11-28, plus the 2 upper cogs from an 8-spd 11-34.
Regarding your ambivalence (in another post) between 406 & 451 wheels: I gather you have not joined the Big Apple cult. I got mine today, and on a 406 rim the 2″ tire just barely fits in the fork; but now I do not have to brace myself for a jolt from every little crack.
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