Ride it. Believe it. Truvativ HammerSchmidt opens up worlds of possibilities with an instant flick of a simple switch. Pure magic. Imagine never having to plan your shift. One is greater than two. There are two gears: and Overdrive. In , everything is locked and spinning together.
Turn the pedal once and the chainring goes around once. In Overdrive, the ratio is approximately Turn the pedal once and the chainring goes around about 1.
The Truvativ HammerSchmidt transmission is a planetary gear design that when engaged and locked down gives you a chainring to pedal revolutions.
When cable is released and the overdrive is engaged, you get 1. At first, the Truvativ HammerSchmidt takes some getting used to…partly because our brains are so front derailleur trained that a new front transmission seems foreign.
When you combine that with the swapped front shifter setup large front paddle goes easier while smaller front paddle goes harder , it takes a ride or two to get used to the new system and lack of shifting issues on the front end. Just riding along, the HammerSchmidt performs exactly as described. You get crisp, fast shifts between the two ratios whether you are moving or not.
The kit also includes spacers to exactly position the collar assembly plate. A transmission gear system allows the sprocket chainring to be driven at a different rate then the crankarm. A conventional crank with chainring will turn together, with one rotation of the crank equal to one rotation of the chainring. In the fixed arm mode, with the inner ratcheting gear disengaged, the arm will turn with the ring as with conventional cranks. When the lever is released and the pawls engage the inner gear ratchet, the chainring will turn more than the crank.
When driving off the planetary system, the ratio of driving increases to approximately 1-to A 22t ring in the photo below will to be effectively equal to driving a tooth ring. Shifting is permitted during coasting, back pedaling and pedaling under load. The operation of this mechanism is apparent event when the crank is off the bike and the ring is back-pedaled. In Figure 2, the chainring is turned counter-clockwise, which turns the inner ratchet gear clockwise.
A logo sticker was placed on the outer chainring and aligned with blue tape on the inner ratcheting gear. The outer ring is turned one full revolution. When the outer chainring has made one full revolution, the inner ratchet gear has rotated approximately 1. The crank can be fitted with different sized rings. These rings are a proprietary design and do not interchange with other systems. Remove the retaining ring on the back side of the crank using a small tip screwdriver such as the SD-3 figure 3.
Pull off the ring cover and the chainring. Rings are available in 22 and 24 teeth. The ISCG mounts consist of three special frame holes around the bottom bracket shell that allow the installation of various chain retention systems.
Adaptor plates bolted between the shell and bottom bracket are not acceptable. The system will load the mounting tabs torsionally, and it is important the tabs be integrated as part of the frame. This assembly collar plate secures simultaneously against both the bottom bracket shell face and the ISCG tabs. The tab surfaces should be machined to insure they are parallel to the surface of the bottom bracket shell.
Additionally, and more importantly, the distance from the shell face to the tabs must be cut to be equal to the predetermined supplied spacers thickness. The kit comes with spacers in sets of three in thickness of 0. In some cases, no spacer is used at all.
By using these spacers the transmission system planetary and sun gear will be correctly aligned. Begin frame preparation by measuring the width of the bottom bracket shell figure 4. Truvativ specifies certain tolerances for the three common shell widths:.
Nominal 68mm shells: If the shell is wider than the tolerances it can be machined narrower as needed. If a shell is narrower then the tolerances, it may be necessary to machine and then add a spacer according. If the shell face is very close to or equal to the lower end of the tolerance, consider not machining this shell face. Begin by facing the bottom bracket shell face as you would normally prepare a frame. This ensures the bearing surfaces of the bottom bracket spindle are parallel and square to the axis of the thread.
If using the BTS-1 leave the threaded inserts in place. These will guide the mounting tab cutter. The cutter fits the handle of the BFS-1 bottom bracket facing set. The holder also fits the handle of the BTS-1 tapping and facing set. A series of shims allow the cutter to reach and cut mounting tabs that are inboard of the bottom bracket shell face.
Before facing, inspect the mounting tabs relative to the shell face. Photo: Andrew Gower. I've seen everything from old Suntour Thumbies to Road Brifters do the job and always gave SRAM kudos for not coming up with some unique stupid cable pull ratio so they could sell more shifters.
When the system was in the direct drive 1-to-1 gear it was akin to pedaling about in a regular granny ring. In the 1. It's a big world of varying terrain. I know, it was a terrible amount of weight added to bikes that were already rolling cast-iron bath tubs. The shifting was like lightning but jumping up from the direct drive 1 to 1 gear ratio to overdrive 1.
And for high-engagement hub lovers, the float in the direct drive ratio was a bit ridiculous, especially when stacked with the float of a hub with crappy engagement. The bottom brackets were awful. I kept two spares on hand. We interrupt this brief trip back to the realities of Gen.
Another issue is suspension kinematics, which I'll talk about in greater detail below. Second only to HammerSchmidt on an Intense Uzzi. HammerSchmidt wasn't coming on bikes designed for HammerSchmidt taking into account the chain position with a 22t ring and the massive improvement in ground clearance. Andrew Gower testing the Lastly, frame prep. I never had an issue shimming a HammerSchmidt onto chainguide tabs and getting it to work perfectly but there were stories about some frames requiring the ISCG tabs to be faced down, along with the expense of a special tool.
The final criticism is that HammerSchmidt was expensive, so if the frame manufacturer's so crappy they couldn't even be bothered to weld the ISCG tabs on square - what's the point? In general my HammerSchmidt experiences were the most positive on hardtails but there were prime exceptions like the Knolly V-Tach and Delerium-T which were very neutral to chainring size.
As any geometry wonk will tell you, the mass adoption of 1x drivetrains has greatly simplified suspension geometry and while it's common to see production bikes being designed to perform best around 32t or 34t rings, other chainring sizes are plausible. Photo: DaamBuilt. Sure there were long single speeds and DH bikes, but I think it's fair to say that HammerSchmidt was the first real attempt at a 1x configuration and it was underserved by the lack of frames built around it.
Two of my favourite no-bs custom builders, Walt at Waltworks and Peter at DaamBuilt, actually ride bikes built around smaller chainring sizes to accomodate big days with big meats and loaded touring respectively so I reached out to them to get no-bs answers on designing bikes around HammerSchmidt.
For a different size chainring, it would get squat-tacular in a hurry. Photo: Waltworks. For example, running a HammerSchmidt on a bike designed around a 32t ring will result in "weird pedal kickback from the chain overcoming the rider weight and the suspension rising.
Other than test bikes from Kona, Norco, and Knolly, I spent all my HammerSchmidt time on a Kona Honzo that rotated between a straight single speed and my 2x1 setup with the 'Schmidt up front. It made perfect sense for me riding Mount Seymour trails as I had an easier gear for getting up the Old Buck climb and I used the Overdrive gear for descending with instant shifts between them as needed.
On my full suspension bike I went back and forth between 1x9 and 2x9, and then 1x10 and 2x10 but, adduction drag aside, once you've had instant shifting, you don't want to lose it. And yet, I'd never buy a Gearbox bike because I can't stand proprietary crap.
My Kona Honzo in So I would imagine a 5-speed HammerSchmidt. Perfect chainline, shift on instant demand under any circumstance or load, and a wide enough spread of ratios to cover anything I'm hitting on the North Shore. Couple that with the low center of gravity, ground clearance, and shear smashability of the solid unit I wonder if SRAM ever sold a replacement HammerSchmidt bashguard and as long as they fixed the crappy bottom brackets the only issue would be the lost revenue in derailleur, cassette, and chain revenues.
Now I'm daydreaming of instant engagement from a roller-clutch driver and wondering how much friction SRAM could have removed from their planetary gear system over the last decade. Couple that with removing the unsprung weight of a massive speed cassette and the fragility of a stork-like rear derailleur.
If dropper posts, suspension performance, geometry, etc could evolve to where they are now, it really does beg the question: "where would the most fun marketing campaign and accompanying drivetrain moon shot be now if there had ever been a Gen 2?
Please log in to leave a comment. Oh, and a good BB. Not too stressed about weight given where it sits but a bolt-on chain tensioner so I can easily use it with a dual FS frame with sliders and optimized anti-squat would be amazing!!! I'd pay a lot of money for that. I am still not sure why the "park bike" in everyone's range doesn't rock this. What more could you need for whistler? I'll also agree with you - this was is? Width of the system, I always think back to when Shimano launched 9-Speed.
Put another way, naysayers and engineers can go about arguing about cog spacing and chain width and stacking planetary gears, and magnetized fluid gear boxes and etc. I'm going to argue that market penetration was mostly due to the brand behind the tech, rather than the quality of the tech. They've also gotten reverb's on a lot of mountain cycles, and we all know those are utter crap. I would love to have a two-speed all-mountain commuter. I think it was a great idea, just badly executed. Maybe some kind of variable roller clutch could have added gears and reduced drag?
I hope you're not referring to that Crom awful automatic 2 speed hub. It's called Automatix. Coaster brake option if you want to really simplify your setup or a standard version for brakes.
To be fair it's not actually a kickback hub but it's sort of the same idea. Easier gear off the line at a stop light and then punch it into the heavier gear once you're moving. One of my buddies had to open his up to change the shift point apparently easy to do - just adjusting flyweights because it didn't shift into the harder gear fast enough. Pretty easy to get used to. Hard to argue with a basically zero maintenance dual-ratio city commuter options.
Personally thought about it for a while, then built up a 3-speed Nexus wheel, and then never used the Nexus wheel because I was happy running my commuter as a single speed. Good reminder that I should probably dig out that Nexus wheel and sell it!
Yeah, Automatix. I should clarify that it works great with the correct wheel size. It was designed with a 26" wheel in mind. I only rode one on a c wheel. To get the shift to happen at the right time, you had to pull the hub apart and re-tension the springs i. As stock, the shift would happen in the 1st few pedal strokes, well before you're up to speed and def when you need it least. That process took more than a few times to get right, as you could imagine.
And sorry for the stupid delay responding. Took you revisiting procore to make me revisit this one! Thanks for putting out great articles like this! This is just one more example, I have always thought Hammerschmidt seemed like a great idea, certainly with downsides, but so does every other option. I will argue that for lots of markets organic pads are acceptable.
What I don't find acceptable are shimano's resin only rotors, I managed to destroy a pair in less than a season. Those Resin only rotors are ridiculous. Not having to replace the rotors before riding the bike is the number one reason to look for Tektro brakes at lower price points. They use Shimano pads and fluid so really - no negatives. Even their crazy-grabby Race pads are organic. No sintered option available. All, different users have different requirements.
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