All City Zig Zag on 650b x 42 mm tires

[Nico]

Alright, my turn to contribute somewhat to the knowledge base. Here's my Zig Zag on 650b rubber. 

The bike is marketed as being an "all-weather endurance road bike" first and foremost, with a listed tire clearance of only 700x37c (32c with fenders). I think in practice, the actual tire clearance (I'd say 700x40c) edges it into the territory the marketers prefer to call "all-road." It's a road bike for sure, but you can take it down some rougher tracks than tarmac. Its carbon copy (pun intended) is the Warroad from sister-brand Salsa. Same geo, with just a tiny bit more clearance eeked out from the plastic construction, and slightly more hinting towards gravel capability in the copy. The Warroad natively fits 650b x 47mm tires, and is packaged that way in some builds. The Zig Zag does not.

Now, here's the SEO phrase for everyone but QBP's lawyers: The All City Zig Zag has clearance for 650b x 42mm tires. Mine are Compass/RH Babyshoe Pass EL's on WTB Asym i23 rims, which fit a pretty true 42mm. With this setup there's 3mm of clearance at the narrowest part of either chainstay, 6mm of clearance at the seatstays, and a mile of clearance in the fork. Because of the shape of the chainstay dimples, the clearance for a 700c x 40mm tire is actually not that much different.

Who should care? People who want mid-to-high volume tires on a nicer-than-4130 steel frame with classic road bike geometry, all the most modern standards you might now want (flat mount disc brakes, 142mm Thru, tapered headtube) and the classic standards you know you still want (68mm English BB, 27.2mm seatpost). That's honestly a pretty rare thing in production bikes right now. I'd say the bikes that come closest currently are the Soma Fog Cutter, Surly Midnight Special, Crust Lightning Bolt, and Bombtrack Audax.

Let's talk about that geo! It's basically ripped off from a truly great bike, the Ritchey Road Logic. Let's compare both on 700c x 30mm tires, the Ritchey's max. The Zig has the same short 415mm chainstays, same 70mm BB drop, and nearly the same mid-trail handling. The seat tube angle gets 0.5deg steeper at 74deg. 

Where things start to get funky is when they borrow from Cannondale's "OutFront Geometry," slackening the head tube angle 1deg to 72deg, but with 5mm longer offset. This lengthens the front center (and toe clearance, and wheelbase, and total bike length) by about 18mm, but keeps the traail only 1mm higher at 57.2mm, and about 1mm more wheel flop. This is fantastic for shorter riders because they usually get screwed by toe overlap in the smaller size frames, and 18mm of bonus clearance is quite a bit! For everyone else, I don't think there's that much benefit. The main other effect is higher stability through rough terrain without sacrificing light steering to higher trail. But if you're already choosing a road bike, you probably don't care about this and may actually wish you were 18mm further over the axle for your alpine descents.

Anyway, that's all to say that the geometry feels like a classic road bike. If one wants that classic road bike geo, and they want higher volume tires, they can do it two ways on this frame. Of course, as we all know here, a 650b x 42mm tire has the same effective diameter as a classic road bike's 700c x 23mm tire, so that way will preserve all those handling features the best. What gets lost in going the way of 700c x 40mm instead? About 17mm of standover clearance, with the BB being raised the same amount as well, and the trail figure raised 5.5mm higher. Basically, it'll feel more like a cyclocross bike than a road bike. The rider who will benefit the most from this is the one who's riding it on chunkier gravel than they ought to, and needs the higher clearance to avoid pedal-strike and the bigger wheel to maintain momentum. That rider better beware of mud and sticks though, because they have very little margin for either.

Personally, having come from that 700x40 setup, I was hoping for bigger perceived difference than I actually felt, particularly in acceleration. I might honestly still end up saying that the sweet spot for the kind of road riding I do on it is extralight 700x32s. I'll need some longer rides to feel out what I think about all this in practice vs on paper. If there's demand I might do a Part 2, but today you'll just have to settle for pictures.

[Pat Smith]

Nico, love the detailed analysis thanks so much for sharing!

Pat

[dailyrandonneur]

This is a very timely post. I purchased this framset in the 55cm size last year, same orange/red color, and built it up with 700c wheels and 28mm GP5000 tires. I was drawn to the mix of modern things (thru-axles and disk brakes, especially) and traditional touches that Nico points out.

It replaced my 58cm Rambouillet, which was always too big for me.This bike is a stablemate to my 1995 Ritchey Logic in 57cm, which I had modified by Bilenky with a new fork and higher rear brake bridge to take 28mm tires and fenders.

The Zig Zag is a fun ride and has loads of clearance with 28s. I've got some 32s to try out and I'll report back. This post has me thinking of borrowing the 650b wheels from my Kona Rove LTD and seeing how it rides with 42s or 38s.

Ed Felker

Washington, DC

On Thursday, August 5, 2021 at 10:50:52 PM UTC-4 Nico wrote:

[Patrick B. Smith]

Hi Ed, nice to see another DCist on here. I'll be on the lookout for a ZigZag around town!

Pat in Capitol Hill

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[Nico]

Thanks Pat!

Ed, you clearly have good taste because my experimental 650b wheelset came off a Kona Rove as well! I'd be curious to hear your thoughts if you end up making the swap. 700c-wise, I think you'll enjoy the 32s much better unless they're appreciably heavier than the 28s. I had the Soma Supple Vitesse's on there previously before I wore them out, and I think that was just about perfect for chipseal. Our roads in my area are getting much worse than that though, with long gaping cracks from heat expansion. The wider rubber is a bit more comforting riding across those.