True Precision Stealth Hubs

Words Andrew Major
Photos Andrew Major
Date Jan 3, 2017

True Precision

True Precision Machining is a high end machine shop located in Goleta, California. It’s a contract outfit making medical, aerospace, and telecom components. The people that work there also happen to be passionate about bikes. Some 10% of their business is manufacturing their performance Stealth hubs in-house for BMX and Mountain applications.

On the BMX side their silent roller clutch hubs win races. From local events to the Gold medal at the Rio Olympics. For mountain bikes they deliver the same instant engagement in single speed, Shimano, and SRAM XD compatible drivers with both standard and Boost spacing options.

True Precision Stealth Hubs

Options abound. Standard or Boost spacing. Bolt-on, thru-axle, QR, 10mm, 12mm, 15mm, or 20mm axles. SRAM XD, Shimano, or proprietary single speed drivers.

My own journey with True Precision began well over a decade ago working in a bike shop. Well supported by the local BMX race scene, we did a number of custom builds for the track. The big money was always on Made in the USA hubs which meant Profile Racing or Chris King BMX hubs for the bulk of our discerning customers. True Precision were silent exotica at that point.

When I saw that they would be at Interbike this year they were a must visit. The guys are friendly and passionate about their products.  They even made time at their booth to pull Stealth hubs apart so David Ferguson could photograph the process.

Teardown Time

With the help of my friend Jeff at Bikeroom and a couple-or-few of Hearthstone brewery’s Chocolate Milk Stouts I wanted to get deeper into the guts of the roller clutch bearing freehub system.

The rear hub uses three Enduro bearings. Two of these are accessible without a specific hub service tool. The front hub also uses two easily accessed bearings. Both hubs have adjustable preload for perfect bearing tension.

True Precision Stealth Hubs

“Precision is our religion.” True Precision, Abbey Bike Tools, and Hearthstone have a lot in common. The perfect teardown trio.

As demonstrated by the guys from True Precision, a basic clean-and-lube is a quick and straightforward process. The front hub is fully user, or shop, serviceable. The rear hub currently must go back to True Precision when it comes time to have the three bearings changed out and the roller clutch bearing itself serviced.

True Precision offsets the cost of shipping the wheel back for a full service by only charging for the bearings. All the other components are bombproof – guaranteed for five years – and the labour is included.

True Precision Stealth Hubs

Jeff puts his Snap-On bearing puller and Abbey Tools press to good use. While the bearings were out he popped the seals and repacked them with a heavier waterproof grease for North Shore winter riding.

For year round riding in adverse conditions, it’s a great idea to repack sealed cartridge bearings with a heavy waterproof bearing grease. At least for the winter. It’s quickly accomplished by popping out the bearing seal with a razor blade and then packing in as much grease as the bearing will take.

In this case, the repack was accomplished outside the hub shell. It is generally possible to repack most hub and frame bearings without removing them.

Stealth Hubs

True Precision’s Stealth hubs utilize a roller clutch bearing for perfectly smooth, near zero drag, freewheeling. It’s a unique system that appears simple on paper but requires an incredible level of manufacturing quality to achieve the tolerances it requires. It isn’t lightweight. It’s meant to last forever.

The system has two major components apart from the hub shell. There is a one-way roller clutch bearing manufactured by INA Germany. True Precision manufactures the gorgeous one piece heat-treated stainless steel hub driver. The stainless freehub bodies and INA bearings should last forever and True Precision says they will replace these parts for no charge with a service if required.

True Precision Stealth Hubs

The roller clutch bearing from INA Germany is sandwiched by a pair of Enduro bearings. The mechanism is lubricated by a half teaspoon of transmission fluid. A basic cleaning is quick and simple and should be performed semi-frequently.

True Precision Stealth Hubs

The heat treated stainless steel hub driver is gorgeous.  It’s available for Shimano or SRAM XD cassette interfaces as well as True Precision own proprietary single speed/BMX mounting system.

The driver interfaces perfectly with the captured bearings in the INA roller clutch. In order for the system to function the hubshell, roller clutch bearing, and hub driver tolerances have to all be spot on.

When coasting the freehub spins smoothly and efficiently on the rollers. When a rider starts pedaling the rollers are loaded between the bearing’s outer race and the hub driver. The connection under load is solid. Engagement and disengagement is instantaneous.

True Precision Stealth Hubs

When coasting the stainless steel hub driver spins smoothly on the INA bearing’s rollers. When a pedaling load is applied the rollers are instantly captured between the bearing’s outer race and the hub driver. Power transfer is impressive.

Roller Clutch vs. Sprag Clutch

True Precision has been making their Stealth hubs since the late 90’s and their reputation in BMX racing is legend. However, it’s only recently that silent clutch hubs have been ramping up interest with the mountain bike community. I think this is at least in part thanks to the Onyx sprag clutch drivers being used in NOBL‘s well-marketed carbon wheelsets.

Here are some handy, brief, videos from Renold bearing that explain the difference between a roller clutch and a sprag clutch.

For the trapped roller clutch bearing the interesting information starts at :35 seconds.


For the sprag clutch the interesting information starts at :37 seconds.

This seems to always invite questions about which of the similar one-way freewheel systems is better for mountain bike applications. In theory a similar quality sprag clutch can handle a higher torque load for the same sized unit hence their use in applications like helicopters. That said, when there is a great deal of debate for other high torque applications the fact is none of our legs are strong enough for that to matter.

In other words. With top quality manufacturing like Onyx or True Precision deliver and top quality components like INA Germany roller clutches they’re both solid options.

Driver Options. Axle Options. Boost.

Like the Stealth hubs, True Precision sells a large range of small parts directly off their website.

Since I am testing their own single speed driver I want to reiterate that they also make drivers that are compatible with Shimano and SRAM XD cassettes.

The standard Stealth hubs are easily converted between QR, thru-axle, and bolt-on applications by simply removing the bearing preloader and swapping out the axles. This is also the simple application to performing a basic cleaning and lube on the hub.

True Precision Stealth Hubs

Axles are easily swapped between bolt-on and thru-axle applications by removing the bearing preloader.

True Precision also offers a Boost spacing options for 148mm and 110mm.  This requires a specific hub shell rather than an axle option and ‘Boostinator‘ type kit.

I have used both the bolt-on and 142x12mm options on my bike. After swapping the axles on the first ride I re-tensioned the bearing preloader as the wheel loosened off. In use the axle systems are equally stiff.

It is worth noting that the bolt-on option uses imperial hardware, not metric. Rather than carry a specific hex key for on trail wheel removal I filed down an 8mm-to-6mm adapter to fit.

For the Single Speeder

With their roots in BMX racing True Precision has developed their own cog and driver interface for their ‘Poacher’ single speed model. Instead of a lockring, the cog is held in place by a cap and four T10 torx head screws. This makes it very quick to swap cogs and to routinely check for proper tightness without removing my wheel from my bike.

It is a very rare occurrence, especially for riders on top of their maintenance, but I have been on more than one ride where someone’s cog, or cassette, came loose on the carrier. The joy of the T10 bolts is I simply added a 1/4″ bit to the Fit-It-Stick Replaceable I carry and if I ever have a problem it’s a quick on-trail fix.

True Precision Stealth Hubs

True Precision’s unique hub driver and cog interface uses four T10 bolts to hold the cog in place. This makes it very quick to swap cogs, check tightness without removing my wheel from my bike, and to adjust chainline for different cranksets and rings.

The system the Stealth hubs use also makes for a very easy adjustment of chainline. This is accomplished by swapping spacers to change the cogs’ position on the driver. It is very handy for swapping between cranks and chain rings with different chainlines and for bike setup in general.

True Precision Stealth Hubs

True Precision’s stainless steel cogs are also manufactured in house. The unique mounting system maximizes concentricity to minimize the variation in chain tension in the drivetrain.

Replacement stainless steel cogs are available in a huge range of sizes. From 14t to 21t. The price of $35 (USD) is very reasonable for USA Made heat treated stainless cogs compared to similar products on the market. I will comment on durability in a future review.

On The Trail

With the chainline adjusted and my preferred Wippermann Connex 108 chain wrapped, I hit the trail. At the time I’m writing this teardown and first impression I have a few months of riding on the Stealth hubs.

True Precision Stealth Hubs

Chainline was quick and easy to setup and the cog clamp holds everything in place tightly. I have checked it semi-regularly but the four T10 bolts have not loosened off at all.

Coming off of the Industry Nine and Chris King hubs I have been riding recently, the instant engagement of the Stealth hubs is notable spinning around on my bike. On the trail I don’t really perceive a performance difference compared to these other super quick engaging hubs even going back and forth.

What I did immediately notice was the sound of silence. Between the True Precision hubs and the single speed drivetrain my bike is silent except for the brake pads on rotors and the cartridge damper in my Lefty. It is actually such a difference that it took a couple of rides to get used to. Despite the fact that both my King hub and the Industry Nine are quieter than stock, because of the lube I run, there is still a remarkable difference.

True Precision Stealth Hubs

The sound of silence. Riding alone in the woods there is no sound but my brake pads on rotor and the cartridge damper in my Lefty. And my thoughts…

I’ve been on a number of rides in the snow lately – local conditions being what they are – and the Stealth hubs have had no issues with the wet or cold. I’m looking forward to getting back on dirt and then writing a full review a few months later.

Pricing

Hubs are available directly from True Precision and pricing is similar to other boutique hubsets. The rear hubs sell for $425 (USD) and the front for $185 (USD). In both cases that includes a five-year warranty on all components except the consumables (bearings). Ceramic bearings are also available as an upgrade.


Silent but… deadly?

Comments

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Jan. 5, 2017, 2:43 p.m. -  t.odd

while I can certainly appreciate the desire for silent hubs, personally for riding on busy trail systems or places with wildlife, I like having my loud Hope hub as a passive announcement of my impending presence

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Jan. 5, 2017, 9:43 a.m. -  mevp

My next rear hub will be silent. Either these or Onyx. Love my current Hope Pro2 for it's reliability, but I'd happily pay an extra $250 for a silent bike. I lust for silence interspersed with a velcro sound of my tires ripping through duffy corners.

So here's my question. I don't run King hubs because while they last forever, they're not reliable. They can get loose or lock up out on the trail if it's been 6 months since they've been torn down and lubed. That's a deal killer for me; hopes might feel crunchy, but they won't fail on the trail. I just want to ride my bike without worry.

Anyone know how reliable these are? How reliable Onyx are? I read this " A basic cleaning is quick and simple and should be performed semi-frequently." and I have visions of King-style loosening and failure on the trail. Reliability first, silence second.

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Jan. 5, 2017, 12:23 p.m. -  DrewM

I can only speak to my experience. I run a bit of copper anti-seize on the threads of the lock-rings/bearing pre-loaders.

The rear hub needed to be tightened after my first ride (common) and needs to be tightened after the first ride when I swap the axle (bolt-on vs. thru) or do a service. Other than that I've had no issues with the hub coming loose. It also isn't an issue I've heard of with TP or Onyx (I don't have enough hours on Onyx to comment personally but everyone I know with NOBL/Onyx is very happy).

I've never had a King up seize up (multiple hubs over many years) but on my single speed I definitely have to tighten my hub quite regularly even with the anti-seize compound on the lockring. I don't find it to be a big deal - part of my regular bolt check - but you're not the first person I know who finds it an annoying aspect of King ownership.

The fact is the True Precision hubs run a small amount of ATF for lube and are not aggressively sealed (spin with so little drag). I certainly wouldn't expect to ride one regularly for six months without a basic lube (never mind a year) in terms of getting optimum performance but in terms of reliability of the product it's a beefy industrial INA roller clutch bearing and heat treated stainless freehub (both with 5 year warranty) so it's hard to imagine the system not being bomb proof.

I only have a couple months on the hub so I'll have more to say once I've thoroughly thrashed them.

I've seen Jeff fix one that was raced DH and absolutely abused at Whistler for a full season. The outside bearings were toast and the clutch barely turned but the driver was fine.

Jeff flushed the roller clutch out with WD40, lubed it, and replaced the bearing and the hub was as new. Pretty good testament to reliability.

That said, it's a pretty limited sampling to say if something is reliable or not. I've known lots of bmx racers in the hubs with only positive feedback but it's an entirely different application.

Thanks for reading!

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Jan. 5, 2017, 1:06 p.m. -  Metacomet

I've got three sets of onyx hubs running at the moment and they've all been pretty much faultless. The oldest is on my fatbike and is over two years old now with no service and over 1000 winter time shit condition miles, along with hauling either a bob trailer loaded with tools and chainsaw, or a rear rack with a chain saw or hand tools during the summer. Very low gear with very heavy loads and huge traction produce a lot of torque on the hub, and that damn hub has not flinched. Feels, spins, and engages exactly the same as it did on day 1. They are sealed very well and use ceramic hybrid bearings. It was the promise of crazy strength and reliability that attracted me to onyx for the fatbike. The other sets have been the same, one with more miles, but the fatbike has seen the most abuse and far and away the worst conditions so prob my best example for reliability.

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Jan. 5, 2017, 1:08 p.m. -  DrewM

Have you pulled it apart to clean/lube the sprag clutch and interface?

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Jan. 6, 2017, 6:31 a.m. -  Metacomet

I pulled them apart to inspect just a few months ago, but everything still looked like new in there so I didn't bother at the time. I just recently picked up the grease they spec for the sprags, so am planning on doing some maintenance soon just as good practice, as I feel like I am neglecting them. Ha!
Also worth mentioning they have some great videos on youtube covering all the basic maintenance for each of their different hub designs. All very simple and quick to tear down.

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Jan. 4, 2017, 7:38 p.m. -  brente

Love the Chris King Buzz I think I'll stick with them.

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Jan. 8, 2017, 6:53 p.m. -  TC

buzz. buzz is noise. noise is the conversion of either mechanical or electrical energy into sound energy.

two bikes, same frame, same size, same wheels, same tires same drivetrain. the only difference: the hubs. the silent one freewheels faster than the one that buzzes. a hub that doesnt have to overcome friction to freewheel is silent. a hub that has to overcome friction is not and buzzes. in the above anecdote, i have to break when following my buddy whom is actively propelling his i9s while i coast behind him. probably irrelevant if you never stop pedaling on the downs or flats…

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Jan. 8, 2017, 7:40 p.m. -  brente

I ride for fun why in hell would I worry about speed I'm not some strava whore.

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Jan. 8, 2017, 7:48 p.m. -  TC

what is a strava whore? there are many reasons to have a concern about drag. i am guessing you probably prefer your bottom bracket to spin freely and without noise? as it concerns fun, given the exact same amount of stamina, an increase in drag will decrease the duration about which you can experience this fun you speak of. all i was pointing out is that noise comes at a cost. want to make more noise with your care stereo? need more amplifier to power to accomplish that. to each their own. but as i said before and as it applies to bikes, its probably negligible, and maybe even irrelevant.

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Jan. 4, 2017, 10:45 a.m. -  Broad Fjord

Hadley hubs! That is all…

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Jan. 4, 2017, 9 a.m. -  Vik Banerjee

I run Hope hubs. rear is 300g and $199USD. I'm 190lbs and they've never let me down. Easy to service and spares are readily available.

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Jan. 4, 2017, 2:18 p.m. -  whatyouthink

i don't think anyone questions how good hope hubs are. they are amazing, I have had them and love them. When you buy these true precision hubs (or onyx or king or I9), you are buying some amount of bling factor. you are building a bike that you truly want to be unique. to those of us living in the states, maybe you are thinking of the jobs you create in this country or just jome amount of "MURICA!". And these are machinist porn.

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Jan. 4, 2017, 7:14 a.m. -  dutchct

Looks like a rear weighs 496 grams

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Jan. 4, 2017, 7:30 a.m. -  DrewM

It's a touch lighter running the thru-axle instead of bolt-on but they definitely are not feather weight.

For XC racing or gram counting builds you can't go wrong with DT Swiss 36t OR if you still want high engagement the I9 hubs are awesome.

Between the roller bearing clutch and the heat treated stainless driver the Stealth hubs are not light. They should last forever - which matters to me but I get it isn't priority for everyone - and the on-trail experience is awesome.

I think it's worth the weight at the centre of the wheel but everyone's mileage/opinion will vary.

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Jan. 4, 2017, 8:02 a.m. -  Cr4w

I'm finding the idea of silent hubs increasingly appealing. I was in Squamish in the fall and I could hear someone's I9 whining away two trails over. My Hope Pro4 isn't that bad but it's got my eyeing these up.

I've heard the Onyx has a bit of a soft feel when it engages, something to do with the sprags turning over. Are the TPs like that?

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Jan. 4, 2017, 8:30 a.m. -  DrewM

A properly lubed I9 hub isn't that obnoxious. When they're that whiny it's because they're dry.

The Stealth hubs engage. Solid. It's like a light switch.

Riding steep tech climbs (like No Quarter) there are moments where I have to let off the pedals (to lunge or backpedal) and the reapply power. I stop pedalling and my bike coasts. I start pedalling (out of the saddle pulling on the bar) and the hub is simple engaged. No float. No mush. Instantaneous. On/Off.

It's really cool.

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Jan. 4, 2017, 11:19 a.m. -  james

the Onyx is on off as well IMO, it's instant. it's just that the on has a slightly soft feel, in a very good way. it doesn't feel metallic, it feels organic. i'm not sure how they compare, i suspect they feel very similar. one has to demo these things and i think here in BC, that can be accommodated by Nobl with some wheelsets around.

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Jan. 4, 2017, 12:53 p.m. -  DrewM

Riding is believing!

I didn't mean to indicate a difference between Onyx and True Precision guts as I only have a few short rides on NOBL wheels. So my comment was only intended to be about the Stealth.

Definitely not a "soft" feeling but also not metallic. It's just on (no engagement feeling).

I know a few guys with Onyx NOBLs and a guy with Onyx hubs and they love them.

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Jan. 5, 2017, 10:03 a.m. -  Metacomet

Soft is a little misleading. Maybe muted would be a better word. There is no hesitation whatsoever with the Onyx hubs, so when you apply pressure to the pedals there is no "clank" like there is with a pawl/ratchet based system, or anything that has to ratchet back a tiny bit. There is no tiny bit with Onyx. The only lag with Onyx is in removing the sag in the chain from its own weight. (Think of fixing a heavy steel cable or chain to a solid anchor, and then pulling it taut by hand. It feels "soft" but its just the slack being removed as you pull it tight.) I think its a combination of the chain going from slack to tense, and the lack of a distinct feeling of engagement that gives it that muted sort of feeling. Both roller and sprag designs "stretch" the outer race of the clutch mechanism by design, but we are talking tens of thousandths of an imperceptible amount. There is nothing mushy or soft about Onyx. Solid is an understatement. It's really quite something. But a word of strong advice. You will Not be able to settle for anything less once you have spent some time on them. I hemmed and hawed over getting an Onyx hub for a long while… And now I have three.

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Jan. 5, 2017, 11:09 a.m. -  JT

I think what they're referring to is a bit of motion under load prior to forward propulsion. Ryan Palmer made mention of it in his Onyx review, and Peter Verdone made a pair of interesting videos showing it on his blog post reviewing the same. I wondered the same thing, if one feels firmer at the start than the other, but truth is I don't care that much. The sound of silence and engagement is too appealing, and either the TP or Onyx will find themselves on my bike this spring. I got to tear down a display TP hub that Ray's in MKE (RIP) had. Machining quality is hands down one of the best examples I've seen, and the process is ridiculously easy.

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Jan. 5, 2017, 11:41 a.m. -  JT

Separate note, I've often wondered why other hub companies don't sandwich their ratchet mech between two cartridge bearings. It makes an excellent sealing system and insures alignment between the pawls and ratchet teeth better than anything else being done. I9's old hubs and some of the Bontrager hubs use one bearing, interfacing the inboard of the freehub and hubshell. The sandwiched mech just makes so much sense. If you're going to use four bearings in a rear hub, why not have two of them interface with the driver and shell, integrating the components better and getting longer life with bigger and more bearings?

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Jan. 5, 2017, 11:59 a.m. -  DrewM

Great point; no idea.

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Jan. 5, 2017, 12:06 p.m. -  DrewM

I definitely don't perceive any motion under loading before acceleration and I'm often out of the saddle standing on too hard a gear… could be roller vs. sprag?

I was thinking maybe I was feeling it but wrongly perceiving it as a bit of "wind up" from the wheel under heavy load but I'm playing with it right now and it's definitely firmly on/off with no dead stroke.

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Jan. 5, 2017, 2:30 p.m. -  49%

I'm assuming by I9 lube, you are referring to DuMonde Tech Freehub oil, unless you have some other secret sauce…

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Jan. 5, 2017, 2:33 p.m. -  DrewM

That is what they recommend (or mineral oil).

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Jan. 3, 2017, 10:46 p.m. -  walleater

I'm almost embarrassed to say that I'd already seen that exact Sprag video ha ha…. I hadn't noticed the roller clutch one though, so it was great to see how the two systems compare. As a hater of loud hubs I'd love a set of these some day.

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Jan. 3, 2017, 10:59 p.m. -  DrewM

I know they're marketing material but I thought they summed things up succinctly. Thanks!

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Jan. 5, 2017, 1:02 p.m. -  Shrockie

A dude went by with an Onix hub while I was doing a little trail work.. nothing but the sound of tires on dirt.. I was instantly very interested. so quiet, you can hear the traction.. OOOohhh. I want some of that!

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Jan. 3, 2017, 10:32 p.m. -  Matt

A single speed setup with Stealth hubs has been a dream of mine for years. A silent bicycle is the literal physical manifestation of perfection and I want one.

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Jan. 3, 2017, 11:38 p.m. -  DrewM

It's a pretty amazing thing.

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