Truvativ HammerSchmidt AM Crankset

The Truvativ HammerSchmidt crankset and front drive system made huge waves in the industry back in 2008 for being the first, mainstream front shifting platform without a front derailleur. With a simple click of the front shifter, you could now change between 2 gear ratios under load or even when you are not pedaling due to the overdrive mechanism of the assembly.

With delivery of the Diamondback Mission 4 for review, we go the chance to get some serious ride time on the HammerSchmidt.

From Sram.com:

Ride it. Believe it. – Every so often, you hear whispers about a new product that promises to change everything, only to be let down in some way. Truvativ HammerSchmidt delivers the revolutionary innovation you’ve been hoping for—and it will completely change the way you think, shift, and ride. Truvativ HammerSchmidt opens up worlds of possibilities with an instant flick of a simple switch. This front transmission’s revolutionary design comprises five main components, each working in perfect concert, allowing you to react to terrain in ways you’ve never imagined before.

Pure magic. There’s no other way to describe what HammerSchmidt feels like for All Mountain riders. Imagine never having to plan your shift. You’ll never see your trails the same again.

  • Arm-Length options: 170, 175
  • Al-7050-TV
  • Color: Tungsten Grey
  • Based on Howitzer BB
  • 15mm crank bolt
  • Chainring 22 or 24 teeth
  • Weight: 1623g (Complete assembly w/ BB)
  • Price: Click here for the latest price

More about Overdrive:

One is greater than two. The planetary gear mechanism at the hart of Truvativ’s new front transmission works like a single chainring with the strengths of the traditional two-ring system — and none of the weaknesses. There are two gears: 1:1 and Overdrive. In 1:1, everything is locked and spinning together. Turn the pedal once and the chainring goes around once. In Overdrive, the ratio is approximately 1:1.6. Turn the pedal once and the chainring goes around about 1.6 times.

How Does The HammerSchmidt Actually Work?

The Truvativ HammerSchmidt transmission is a planetary gear design that when engaged and locked down gives you a 1:1 chainring to pedal revolutions. When cable is released and the overdrive is engaged, you get 1.6:1 chainring revolutions for each single pedal revolution. The result…you get either a 22/36 tooth setup or a 24/38 tooth setup depending upon your configuration and this is all done through a single chainline without the need for a front derailleur.

Intended use at this time is for AM to FR/DH bikes with ISCG tabs for installation. There are two different models (AM and DH/FR) and the AM model is tested here.

Short Truvativ Hammerschmidt Promo Video

On The Trail: Truvativ HammerSchmidt

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.

Truvativ HammerSchmidt AM

Just riding along, the HammerSchmidt performs exactly as described. You get crisp, fast shifts between the two ratios whether you are moving or not. Under climbing load, the shifts are consistent and allow you to change ratios quickly even when hammering out of the saddle. After awhile, it becomes second nature to rely on your front shifting to carry more duties than you normally do with a front derailleur based setup. Simple clicks back and forth via the HammerSchmidt specific front shifter and you are set whether you are moving or not.

There are two things that you do have to get used to when using a HammerSchmidt.

  1. The wide ratio between regular pedaling and overdrive – With the 22/36 and 24/38 options depending on the ring you use, it is wider than typical 2×9 setups I have run in the past (22/34 or 24/36). With the 24/38 option, I found myself having to shift the rear derailleur a couple of positions with each change in front under steeper climbing changes that used to only require a front ring change.
  2. More Swarming Bees – I also found that I liked to stay in the 1:1 option as much as possible while coasting and pedaling because the HammerSchmidt drive sounds much like a hub freewheeling (a little bit deeper pitch) when you go to coast.

The real beauty in the HammerSchmidt is what it ultimately brings to AM and longer travel mountain bikes. The fringe benefits are really noticed during riding. With the HammerSchmidt, you get unbelievable ground/bottom bracket clearance. When navigating down trees and other trail obstacles, you no longer have to worry about how large your big ring or bash guard is…you have almost limitless clearance as you hop up and over. You also get a straight chainline that has all of the benefits of chain retention systems with none of the drag. As you blow through rock gardens and other rough terrain, there is no worry of the chain dropping or miss shifts as you are basically dealing with a 1x setup on the front ring.

Is the HammerSchmidt the end of the front derailleur?

Well…not yet. While there are a ton of obvious advantages for running a planetary transmission up front, there are still the issues of weight and price until the system becomes mainstream. However, it does bring solutions to a lot of the issues that technical and downhill riders run into while on the trail. The HammerSchmidt is a huge step forward in front shifting progress and we are even seeing bikes like the custom steel hard tails out of builders like Steve Stickel (click here to see pictures) getting the HammerSchmidt treatment to accommodate new frame designs and geometries.

Positive: Truvativ HammerSchmidt Crankset
  • Effortless shifting under load or while coasting
  • Massive amount of ground clearance
  • Chain retention/guide protection without the guide or drag
Negative: Truvativ HammerSchmidt Crankset
  • Price – Still very expensive
  • ISCG tabs required for install and installation not for the typical garage wrencher
  • Wide gear ratios can cause some more rear shifting in certain climbing situations
  • Weight

The Truvativ HammerSchmidt is a great leap forward in front shifting technology. If you are un-concerned with overall bike weight, I would suggest taking a look as the HammerSchmidt is your answer to getting rid of front shifting headaches.

Click here for the best price on HammerSchmidt

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11 comments

11 comments

Used Transmission October 19, 2010 - 11:21 am

This is cool! And so interested! Are u have more posts like this? Plese tell me, thanks

Reply
Greg September 26, 2010 - 9:30 pm

Robb what are your thoughts on the durability and long term operating costs of the HS? Will it cost a lot to have it serviced or rebuilt and how often will it need it.

Reply
Robb Sutton September 27, 2010 - 11:54 am

Over the course of my review, there wasn’t anything that needed to be done to the HS. That said, over the long term you are going to wear that front chainring faster than you would a middle ring and that can lead to wearing your chain as well. As far as the maintenance to the HS itself…there shouldn’t be too much to do as long as you take care of your gear and keep things clean.

Reply
Greg September 30, 2010 - 7:25 pm

Thanks. It am trying to justify the cost to myself. If the product lasts and proves to be durable, then i think it is worth the price. I haven’t seen any review or comments about it failing or breaking so far…

Reply
jeff September 15, 2010 - 2:03 pm

I read somewhere recently where a guy put HS on a rigid single speed, but said it sucked because of the amount of drag in the HS system. Did you notice any of that drag?

Reply
Robb Sutton September 15, 2010 - 2:05 pm

A properly setup SS setup has almost zero drag, so comparing a SS chainline to a gear setup is not even a fair comparison.

I noticed about the same drag as a geared setup without a chain tensioner and less drag than with a tensioner.

Reply
Pork n Cheese September 16, 2010 - 2:07 pm

I know a couple guys who have setup AM hardtails with a “2×1” setup using a HS and their biggest complaint was the weight change from a 1×1. From my perspective there is going to be some energy loss because even though you have a multiplier you are losing some energy to change in form (e.g. noise). But I would agree that comparing a geared setup with a SS setup is not apples to apples. But was the real question comparing a 2×1 (with the HS) to a 1×1? Technically still geared but your chainline and sag are fixed just like in a 1×1.

Reply
Robb Sutton September 16, 2010 - 3:53 pm

I would be interested to see a HammerSchmidt mated up with a Rohloff rear.

Reply
Pork n Cheese September 15, 2010 - 1:55 pm

I’ve been riding my HS AM on my TBC Covert v2 for almost two years now and the chain line can be a concern on some rigs. I haven’t found the OD orbital noise to be that bothersome at all and spend most of my time in OD. I’ve seen no adverse suspension effects with the HS on the Covert. Another very insignificant, bothersome issue is some frames can be a pain to get the cable routed on well. You’d think they would work out a better alignment. My two favorite mods were the HS and my KS adjustable seatpost.

Reply
Alex September 15, 2010 - 1:26 pm

You forgot to mention the difference to many suspension designs that the 22t chainline makes. Most pivots are placed with the middle ring in mind. Some manufacturers even state that running a hammerschmidt will negatively effect suspension action.

Reply
Robb Sutton September 15, 2010 - 1:45 pm

Alex

You bring up a great point. It can affect some suspension designs. Without a back to back comparison between the HammerSchmidt and a conventional crankset…it will be hard to measure the effects.

Reply

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