14 April, 2022

Neutrino Mini-Velo Tips, Tricks, and FAQs

by Connor

With our recent shipment of Neutrinos having arrived earlier this month, and with mini-velo wheelsets on the way any day now, we decided it would be a good idea to brush up on the technical specs of the bike itself and offer some suggestions of how to build up a complete bike. This quick and concise rundown is designed to help you find the correct build and fit for your own Neutrino Mini Velo. 

Size Guide

You're not going to start a build kit without buying the right frame size first, so let's get into fit. Our Neutrinos come in Small, Large, and XXL. Because of the non-traditional nature of the frameset, we designed the Neutrino in only three sizes to span a broad range of heights and body dimensions. 

The Small is best suited for folks in the sub - 5'6" (167cm) height range. Because of the low-slung, BMX-esque shape of the frame, inseam and stand over are largely irrelevant when it comes to frame size, making this bike ideal for folks struggling to find a bike small enough for them. The Large is our most popular size, and is designed for folks between 5'7" (170cm) - 6'1" (185cm). The XXL is for the taller folks, designed with those taller than 6'1" in mind. A higher and longer top tube boasts proper fit in a tiny package, and the steel construction of the frame provides a sturdy foundation for all sorts of tall riders. The XXL size frame doesn't really fit into a checked bag, but we had a lot of people asking for a size larger than Large, so there you go.

Note that as the headtube length increases as you go up in sizes, folks with more reach looking for a more-relaxed fit may still have to add a fair number of stack spacers to find the correct fit. Keep in mind that you can always cut more steerer off and punch down the star nut - you can't add it back on. It's always best to throw the wheels, cranks, seatpost/saddle, and headset on with your desired bars, and play with height. Scoot around, coast and soft pedal, and find a generally ideal position for the type of riding you plan on doing- then add 10-20mm of stack above where your stem is mounted, and cut that much above. You can always shave that down, but if after a couple of rides, you find your stem is just a little too low, you'll be glad you waited and saved the extra 20mm or so.

Interjection from Igor: the steerer tube is steel, so feel free to stack them up as much as you want. You may get some weird looks from the Slam Your Stem Society, but I think you should embrace the tower of power. 



The Neutrino is a funky animal at first glance, that much is certain. However, it's the unique shape and low-slung design that allows it's rider to set it up practically however they like! Many bikes nowadays are designed solely for flat bars or drop bars. But, like the rest of our bikes, the Neutrino is designed with very neutral "effective" geometry that allows the use of either bar style. So feel free to use drops, flats, uprights, or alt-bars. 

As with any bike, given the dimensions of a person and their bike, flat bars offer a wider hand positioning, bringing the arms out and the shoulders wide. This has a similar effect on reach as a drop bar with a slightly longer stem. I think back to my drop bar conversion on the All City Nature Boy I rode at GRUSK last year (I wrote a blog post about converting this bike from flat to drop bar). I was running a 780mm riser bar with a 40mm stem. After going to a 44mm wide drop bar, I used an 80mm stem, and felt that I was in about the same position, if not slightly more forward than before. Suffice it to say, if you're planning on running a drop bar setup, keep in mind your stem length. You may want it slightly longer than you think- it's easy to look at the Neutrino and think the reach is going to be too short. 

When it comes to stems, everyone's got their own preferences. Much of this will also be dependent on what bars you run, and will affect your stack spacing as well. If you're running a riser bar or something like a Klunker, you may find that a standard, straight threadless stem is your best bet, as the shape and rise will be predicable and tuneable by adjusting stack. If you're looking for big rise and a little bit of style, some very common stems to run on the Neutrino are Cigne and Happy stems - a Cigne with a Nouveau Randonneur is perhaps our most wild looking and fun to ride Neutrino we've had here. Using riser stems also reduces the amount of steerer tube sticking out of the headset, and reduces the number of stack spacers needed - an aesthetic preference, of course.

Generally speaking, we tend to recommend people start with a 90mm stem. That's the most medium position for most flat or drop bar setups. You'll find pretty quickly if you need a shorter or longer stem to get a good position.


When we came out with the 2nd-gen Neutrino, we added a stealth-routing hole for a seat-tube exit for dropper seatposts. Obviously, you're more than welcome to use a standard, rigid seatpost, but the availability of the dropper allows more adjustability, compact size, and ease of dismount when riding in congested areas. 

With either option, please note that it's more than likely that you'll be having quite a bit more seatpost sticking out of the frame than you would on a standard bicycle. Also keep in mind that if you're on the taller or heavier side, you want to make sure that you have a safe amount of seatpost in the seat tube. All seatposts have a minimum insertion, so be aware. We have a long, Medium Setback Seatpost we recommend for the Neutrino.

Shifty Bits

We've done a bunch of different builds with various drivetrains, so use this as a guide from our testing. Our goal is to keep things simple so that you can enjoy the ride rather than worrying about your drivetrain.

The Neutrino was designed to be a 1x specific bike. That is, because of the positive bottom bracket rise you need to buy a specific mini-velo/folding bike front derailleur with a 35.0mm clamp - which according to my Google-fu does not exist.

Our suggestion is to use a road/CX 1x crank. The Neutrino has a 68mm bottom bracket shell (English threading) so you can run a square taper setup like our 1x Crankset with Narrow-Wide Chainring (coming back in stock in about 1 month) or with a 2-piece crank like a Sram Apex, Shimano GRX, etc. You can fit up to a 48-50t 1x chainring, but the larger chainring you go, the weirder the angle gets between your cassette cog and the ring, making for delayed shifting and less slack in the chain to make up for chainline. We've found that 42-44t is the sweet spot for most builds. 

The rear end uses 135 disc QR spacing, so any modern QR disc hub in 135 should fit. This leaves some of the drivetrain choice up to the customer, but we've always found that the Shimano HG11 freehub body offers the most versatility when it comes to sourcing and using drivetrain parts. The key for a rear derailleur is that it needs to be fairly short.

While standard Shimano/SRAM short-cage road derailleurs are likely the most common to be found, they can only usually handle a 28/30t max cog. If you wanted to fit a slightly taller cassette, the Shimano Zee MTB derailleur is a short cage-size derailleur that fits cassettes ranging from 11-32 to 11-36. This is the ideal derailleur for this bike, as it is small enough to not rub on the tire, but has the capacity to run up to a 36t cog.

The reason you can't use anything longer than medium cage rear derailleur is because the dishing of the wheel, and the depth of a standard cassette rear hub, results in the tallest cog being very close to inline with the widest part of your tire. Since a 20" wheel is very small, this leaves little room for a derailleur to wrap around a tall cog, while not rubbing the end of the cage on the tire, buzzing your derailleur. Trust us, we've tried all sorts of derailleurs in testing.

As far as drivetrain setups here is a sampling of our favorites:

Alternately, you can always run a single speed! Igor is running 42x16 on his Neutrino, which is great for running errands around town and cruising to the park with the family. I wouldn't go any lower because then you'll be spinning all the time.

Wheels and Tires

As stated before, the Neutrino is designed only for standard 20"(406 bead seat diameter) wheels, with a 135xQR disc rear spacing, and front 100xQR disc spacing. The benefit of the Neutrino's 20" standard size is that you can use most any BMX rim (known for their durability and wider tire width), and some even come with tubeless options (oooh).

We sell Neutrino-specific wheelsets on our site, using our Rear and Front Disc Hubs, and Velocity Cliffhanger rims, assembled by hand at Velocity with color matched spokes. Demand is high, so be sure to sign up for product stock notifications, and keep your eyes peeled - they'll be gone before you know it.

As for tires, we recommend something between 2.1-2.3". That's the sweet spot for bmx and 406 tires. One thing you want to look for in a BMX tire is whether they use single or double ply construction. Unless you're hucking your Neutrino down a 7 set or doing a gnarly smith grind, go for single-ply tires. Double ply is for hard landings and tricks, and single ply is for bmx racing. Single ply is lighter and more compliant and more fun to ride for 99% of us. Of course, if you find a cool tire color.....then all bets are off on construction.

So there you have it! A basic rundown of the essentials you need to know for building up your first Neutrino. Obviously, if you have any questions, please refer to the product info page on our website, or reach out to us directly at info@velo-orange.com.


Vikram said...

What about internal geared hubs? Any reason those should not work with Neutrino?

Igor Shteynbuk said...

As long as you follow the hub's manufacturer's recommendations and they work with 135mm qr dropouts, they should work fine!

Unknown said...

Thank you for
posting this info!

Felkerino said...

I'm interested in the chainring size. My experience was that 20-inch wheels needed about a 8- or 10-tooth increase in chainring size to replicate 700c wheel experience, meaning not spinning out. Is the idea with a 42 tooth ring that one will just have to stay in the smaller cogs more of the time? Also I'm intrigued by the upsloping chainstays -- and why you can't just put a double derailleur on there with a 48-38 chainring combo.

This is a very helpful post, especially addressing the fit considerations!

Douglas M. said...

Those with prior experience could take some shortcuts here, but as was mentioned in this article, it generally is a good idea to begin by not cutting and reducing the length of the fork steerer tube, and installing a handlebar stem on that tube and all of the spacers needed to cover the full, remaining length of that tube, which allows for maximum high/low stem height adjustment and for any additional steerer tube mounts such as for a front bag, headlight, phone, water bottle, flashlight, bell, etc. Then spend some time, hours, days, weeks, etc., riding the bike on the sorts of roads/trails the bike would be used on. And then when YOU have the bike set up just the way YOU want it, cutting and reducing the steerer tube length becomes optional.

Anonymous said...

any chance of a mini in the works without the disc brake requirement?
I like the idea of the mini, but not a fan of disc brakes.

Igor Shteynbuk said...

Hey Ed,

Yes, if you're cruising you would be in the taller end of the cassette. I used a 48x11-28 on our original prototype and found it great for a speedier setup. Actually in Russ if PLP's visit, he did a review of the Neutrino with that gearing I believe.

Double for a mini is kind of tough. You first need to find a positive bb derailleur (it uses a different angle so as to not hit the tip of the cage on the chain). Then you need a 35.0 clamp for that derailleur. Let me know if you can find that combo! Most I've found are for 28.6 seattubes.

Long story short, 11-28/32 and 42t to 48t is a great setup for the majority of people. Let me know if you wanna ride mine, I'll be putting gears on it soon.


Igor Shteynbuk said...

No plans for a rim brake version for now. We tossed around that idea when we first developed this bike, but today's disc brakes are so easy to set up and maintain.

Anonymous said...

I noticed your video on packing the Neutrino in the Odyssey Traveler Bag. I recently picked up a large frame partly for bringing on vacation when flying. Is this still the bag you would recommend? I am a bit concerned that it may not provide enough protection, but maybe I can reinforce and pad it while packing. I also read on an old review somewhere that VO might have a bag in the works for this bike, any chance that is true?


Izzy said...

What's the widest tire that can fit in the rear WITHOUT a fender? I vaguely remember seeing photos online of a Mini Velo with 2.8s.

VeloOrange said...

@ Izzy- 2.4 is the widest you can fit into the frame without a fender.

R1100RSL said...

Will you please consider breaking up just a few wheel sets, for those of us that either need a replacement wheel or happen to have a rear wheel left over (after going IGH) and are considering building yet another Neutrino (hand raised).

Also, is there any sort of rear rack available that isn't a mile high and likewise doesn't look ridiculous, perhaps one with a tombstone or decaleur to hold a (yes) second rando bag.

Anonymous said...

With the smaller wheel set, how does it handle low frequency/high amplitude stutter bumps? I’ll assume a supple tire is best, since there is no suspension per se, but it would be necessary to leverage the natural suspension characteristics of the combined bike and rider? I am very much excited to buy Nuetrino and experiment with suspension idea. Maybe Allsop stem with shock in post like the thudbuster. Is position on bike capable of aero shape or is it more upright position.

VeloOrange said...

@R1100RSL- We'll look into that once we get better stock of wheels perhaps.
With the rear rack, it's tough as most racks are designed around a 26" to 700C wheel range, so it would require a special rack, specific to the Neutrino. It might be worth looking at racks for Brompton bikes, as that frame uses a similar size wheel.

@Anon 4/20/22- in our experience, the frame and tire sizing does well with bumps and such. Yes, going with a more supple tire helps to reduce any shock aspect. Your position on the bike is variable, so you can make the cockpit set up as aero or as upright as you wish. It just depends on the stem and bar combination you wish to use.

Anonymous said...

I ask (maybe wrongly): with such a long head tube wouldn't it be better to anchor the front rack directly to the frame (like Brompton) freeing the wheel from the weight of the load?

VeloOrange said...

@ Anon 4/27/22- there is no "correct" way, just different ways. We prefer to have the rack for the bag as it is more universal. The Brompton system is specific to them and requires a special bag, whereas with ours, any bag can be attached to the rack. We've not found that the typical weight being used on a rack like that (usually between 5-12 lbs) is any better being attached to the head tube or attached to a rack on the front wheel.