New tires for Gios Mini Velo

Well, let the upgrades begin. My Gios Feluca came stock with some crappy components. I’m still trying to get some SRAM Rival components, but these the Kenda Kwest tires need to go now. But “mini velo” means small wheels, so there’s not a lot of choices when you have 20x1-1/8” (451) rims.

Priomo tires.jpg

There seems to be a lack of consensus among mini velo manufacturers as to which 20” standard to use (ISO 406mm or 451mm). Flatbar mini bikes more often have the 406 and the higher performance tend to use 451. Personally, I would have preferred 406 since there is slightly more variety in that size, but that wasn’t an option on the Gios.

After digging through distributor catalogs, I settled on some Primo Comet 20x1-3/8” tires, more commonly associated with performance recumbents. Compared to the Kenda tires (1-1/8” nominal width), the Primo are a little fatter, have a more supple casing and a smooth round transition over the tread. They are a little bit lighter than the Kenda too, but both are wire-bead.

The ride quality seems improved, but I have yet to try pushing these in fast turns. Since the bike is built around short reach brakes, this Primo tire eats up ever bit of clearance under the rear brake bridge and fork crown. I wish that the rims were wider. Lately my experience with my Bianchi dropbar mtb and my Hed-rimmed road wheels leads me to believe in using wider rims to improve tire performance, but for my Gios there is another advantage. The tires extend out so far beyond the rim’s brake surface that the brake caliper quick-release won’t open enough without slackening the barrel adjuster too. If the rim was wider, the quick-release alone would probably be sufficient.

On an unsuspended mini velo, the tiny wheels definitely do ride harsher than 700C for the same width tire, hence my desire for the fattest tire that the frameset could accept. However, some people do loaded touring in Japan with mini velo touring bikes.

Gios vs Bianchi.jpg


13 Comments

yeah the 451s are hard to come by. The primo comets are great and fast but I do think schwalbe makes the marathon in 451 as well. My fav all around tire by far.

Update: the ride is much improved with the Primo Comets.

Stupid question, but as neat as mini-velos look, in N.America where space is not so much at a premium as Japan, what’s the point of an inferior wheel size?  Not meant to troll, but someone please explain the mini-velo phenomena to me.

And as for space at a premium, I had little trouble with my 58cm bike in Japan for three years…

I think in the US, the mini-velo phenomena is mostly Mark (mostly) and the sales volume is matched only by disc-brake road bikes.

Non-troll, the smaller wheel has advantages in strength, aerodynamics, and mass.  (There are also disadvantages.)  Dahon and Bike Friday have various info on their sites.  I like my Dahon Helios best for steep paved hills - I think it’s the lower rotating mass that I appreciate most.

Honestly, I’m not the only one interested in mini velos, but it’s not likely to sweep the nation.  If you’re riding a 58cm, going with smaller wheels isn’t going to decrease the overall size of the bike as dramatically as it would if you ride a 49cm like me.  Next time I’ll take pix of my regular Bianchi and the Gios mini and you’ll see what I mean.

One thing is that the bike does nicely when I’m trying to go thru crowds of pedestrians.  It makes a FANTASTIC lunch bike when going to the Pike Place Market.  If I could mount a front rack on it, it would be the bomb.

Handling is another thing.  I’m still evaluating it, but either handling is inherently different with the smaller wheels or the geometry of mini velos is still being refined.  More on that later.

I race 20” wheels on my gravity bike.
ZooBomb

...but there are like 4 of us in north america. As for ‘regular’ bikes, read up on Alex Moulton (not dave), he did lots of studies and fun stuff with smaller wheel sizes. I couldn’t find the exact article I remember but here are a few links:

Stridaforum

Hadland

GS

There is also a lot of science behind why HPVs use smaller wheels. Remember Sam Whittingham just set a world record!

oh, and I’m wrong about the marathon, it was the stelvio I was thinking of.

I’m personally rolling on Schwalbe Big Apples, buttery smooth rolling resistance.

However, I’ve heard great things about Schwalb Marathons and primo comets.  Come by the bikeforum sometime!

The small wheels for HPVs largely hinges on reducing the overall aerodynamic cross-section of the vehicle and rider; lower the vehicle with small wheels and then drop the rider down in between.  On a standard bike, the rider is always bolt upright in the wind, comparatively speaking, so no gains really.  But for an HPV, the aerodynamic advantage totally overcomes the relatively small increase in rolling resistance.

Moulton basically argued that small wheels with high pressure tires and suspension on modern roads made more sense than big wheels.  Remember, he was a automotive engineer at first, so his vision of bikes mirrored the evolution of cars.  My bike has no suspension, so fatter tire is better. I kinda like Moultons, but so expensive. 

I’ll look for the Big Apples, but I got the feeling that they won’t fit my bike.  The rear is so tight that the irregularities in the casing have the rubber flash from the mold process grazing the underside of the brake caliper for about 5deg of rotation.  TIGHT!

 

The first time I rode the Bettie (cargo bike) in a windstorm I had a very good understanding of how rider position affects aerodynamics. Or riding a Brompton with a bag on the front into the wind, has I think the aerodynamics of a [stair car](http://evansparks.wordpress.com/2008/01/07/do-you-want-a-bluth-style-stair-car/).

@booka

unfortunately those are a different nominal 20” standard (ISO 406mm) as opposed to the 20x1-1/8” (ISO 451mm) that my bike has.

Have you tried using v-brake pads to get more clearance for your tires, and better brake performance for cheap? Works for me. BMX types are shorter, for small rims.

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