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Tech Talk: Mr. Zinn rides SRAM’s new road groups

  • By VeloNews.com
  • Published Apr. 10, 2006

By Lennard Zinn

The Rival road group.

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Introduced at last year’s Interbike trade show, SRAM formally rolled out its new road group at Sea Otter this week, giving media and others the chance to actually ride what the once-little company is using to take on the giants of the component industry.

The company is actually introducing two new road groups: the top-of-the-line Force group and the price-point Rival. Both share the same design on all components, with the Force group getting extra touches like carbon fiber lever blades, a magnesium lever body, and titanium gears and bolts. A pair of Force levers, for example, weighs in at 305 grams, a full 114 grams lighter than a pair of Shimano Dura-Ace STI levers, 19 grams lighter than Campagnolo Record carbon and 43 grams lighter than Chorus carbon levers.

DoubleTap on a single lever
Built around its innovative “DoubleTap” single-lever shifter, the road groups, say SRAM engineers, represents a big leap forward for the company and offers an elegant shifting option for roadies. The DoubleTap shifter has at its heart and attached to the shift cable a toothed gear, with a tooth for each rear cog. Two spring-loaded pawls engage the same tooth of the gear at any given time. An inward lateral push on the shift lever lifts the outer pawl, which dislodges the inner pawl from the gear tooth.

Tech Talk: Mr. Zinn rides SRAM’s new road groups

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“It’s like a mother pig with too many piglets,” says Brian Jordan, the engineer who designed it. “If she has eight babies and only seven teats, when one comes in to suckle, it knocks another one off.”

Dislodging the engaged “safety” pawl that holds it in gear releases the cable and allows the spring on the rear derailleur to pull one shift worth of cable and rotate the gear one notch until the pawls fall into the next tooth valley with an audible click. A short push on the lever performs the chain dump function of the inner lever on Shimano STI or the thumb lever on Campagnolo Ergo Power.

A longer push on the shift lever not only dislodges, but also holds the inner pawl away from locking up the teeth while the outer pawl continues to engage and push the gear in the opposite direction to pull cable, moving the chain to the larger cogs or to chainring. This longer push (the second tap of DoubleTap) performs the function of the lateral push on an STI brake lever or on an Ergo Power lever.

“It took us about three weeks to design a system we thought might work, and then it took a few more days to make a working prototype mounted to a board,” Jordan remembers. “When I explained to people that it was a shifter, they could not understand how this big thing was going to fit into a lever!”

Tech Talk: Mr. Zinn rides SRAM’s new road groups

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Jordan managed not only to miniaturize the shifter mechanism, but, due to its elegant simplicity and few parts, made it lighter and smaller than those of the competition. Regarding ergonomics, Shimano’s lever needs the large knob on top to house its mechanism for the brake lever to both brake and shift. And Campagnolo’s lever needs a large base to house the thumb lever mechanism. But SRAM’s lever is designed around fitting the hand, since the shift mechanism takes up so little space and can be located anywhere inside the lever. The lever body’s shape is similar on top to Campagnolo’s, but it is slimmer at the base. There is no reach adjustment on the brake levers, but SRAM claims that the levers are closer to the bars and slimmer than its competitors, and since the brake lever is not used for shifting, both the brake lever and shift lever are easier to use for small hands.

A long push can shift up to two gears at a go. The short-push, chain dump function can only drop one rear cog at a time. The front shifter has a feather adjustment click to deal with sharper chain angles on the inner chainring, but there is no feather on the outer chainring, because a light touch on the shifter just drops the chain off to the inner ring.

Ben Jacques-Maynes of Team Kodak Gallery-Sierra Nevada, was an early adapter, first riding the group at the national criterium championships in Downer’s Grove last season. He developed a technique for sprinting that he calls “trigger shifting.” He hooks his right forefinger around the shift lever and pulls it back to the handlebar and holds it there, since it, like Campagnolo’s cable-pulling lever, pivots back toward the bar. While holding tightly to both the drops of the bar and the lever, he can simply twitch his forefinger inward to cause upshifts.

“I was a Campy guy, and Campy riders tend to play with the lever behind the brake lever, since it flips back toward the bar,” he explains. “I was just playing around with this lever that way one day and discovered this way to shift. I called up SRAM immediately, and they thought it was cool, too. With Campagnolo, to get my thumb on the lever and shift, my power in a sprint drops by over 400 watts when shifting, from up around 1300 watts to under 900 watts. With Shimano, I lose even more; I practically have to sit down, shift, then stand up again and restart my sprint. With SRAM, though, my power in a sprint drops by only 40 watts; I can’t even notice it. I think it’s a huge advantage, because I can start my sprint in a much lower gear and steadily shift up as my speed increases, whereas most guys start in a huge gear and grunt it up to speed, because they don’t want to shift during the sprint.”

Tech Talk: Mr. Zinn rides SRAM’s new road groups

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Brakes
The brakes are dual-pivot, with titanium bolts for Force, bringing the weight in about 30 grams lower than either Dura Ace or Record. The pads have a compound for both wet and dry conditions, but the pad holder fits a Shimano or Shimano-compatible aftermarket pad.

Cables and housings for both brakes and shifters are standard, high-quality die-drawn cables and lined housing. Both cables are wrapped under the handlebar tape, with the shift cable routed behind the bar.

The derailleurs
The rear derailleur appears to be fairly standard in design, with the Force getting titanium fasteners and a carbon cage. Both derailleurs get “SRAM Exact Actuation,” which is not quite the one-to-one actuation ratio of SRAM mountain derailleurs, so Force and Rival shifters are not compatible with SRAM X.0 rear derailleurs. SRAM believes that the precise action of its derailleurs benefit from the lower cable tension and longer cable pull provided by its actuation ratio, which is around half that of its competitors.

The Force and Rival front derailleurs are the same, save for finish quality. According to Scott McLaughlin, team leader of the design-engineering group responsible for taking a SRAM product from concept to completion, front shifting provided a major hurdle.

Tech Talk: Mr. Zinn rides SRAM’s new road groups

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“We wanted to make it work with both standard and compact chainrings, yet be easy to shift.”

It takes a lot of force to push the chain up onto the big chainring, and to create the precision they wanted with a light touch was something they worked long and hard on at both ends of the system – within the lever as well as the front derailleur and with the design of the chainrings.

Chainrings, Cranks and Bottom Bracket
The chainrings are “coined,” a forging (high-impact stamping) process, to make the teeth harder and more durable than they would be had they been machined. The hard-anodized finish with Teflon coating makes the chainrings tougher yet and helps the chain move more easily from one to the other. The tooth shapes and ramp locations further assist in this effort. They come in 39-53 as well as compact 36-50 and 34-50 configurations.

Tech Talk: Mr. Zinn rides SRAM’s new road groups

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The cranks are forged aluminum for Rival and carbon with an aluminum skeleton for Force. Both have the Truvativ GXP (Giga X-Pipe) integrated-spindle design. This design features external-bearing cups with a large bore, but while the drive-side bore is the same size as Shimano or FSA, the non-drive-side bore is smaller. There is a step on the spindle to butt against the inner race of the left bearing. The left arm tightens onto what appear to ISIS splines. It turns out, though, that looks can be deceiving. The splines are slightly different than the industry standard in that the engagement section is 3mm shorter and has slightly narrower valleys.

The non-drive side butts up against the outer face of the left bearing’s inner race. Pinching the left bearing inner race this way ensures that the right bearing carries no axial (side-to-side) loads – only radial loads from both the right leg and the chain – thus giving it a longer lifetime, more like that of the left bearing. Other integrated-spindle crank designs, which have the same bore diameter in both bearings, depend on the consumer to preload the bearings enough to prevent lateral movement but not so much that the bearings wear out prematurely from high axial forces they are not designed to handle.

Chain and cogs
The 10-speed rear cogset comes in 11-23, 11-26 and 12-26 configurations and fits on a Shimano freehub spline. The largest three cogs are mounted to an aluminum spider, and the seven small cogs slide on individually. The unique feature of the cogset is called “Open Glide Technology” in which there is a missing tooth on each cog that is only a single tooth different in size from its neighbor. This design came out of SRAM’s Schweinfurt, Germany center, the former Sachs plant that encompassed the old freewheel maker, Maillard. All cogs are steel, and the cogset is the only item shared across both groups. SRAM is missing the lightweight titanium cogs of its competitors and hence gains some weight back in this area. The company plans to improve on this in the future, and since its system uses the same cog spacing as Shimano, a rider can instead use lighter Dura-Ace cogs. And of course, wheel changes are no problem, since it is fully Shimano-10-speed-compatible.

Mark Pippin, SRAM’s product manager for cranks, chains and cogs, says, “Making a sub-6mm-wide chain for 10 speeds is a challenge, but it was one we needed to take on anyway, being in the chain business.”

The PowerChain has hollow pins, and, like other SRAM chains, a master link, but in this case, the new PowerLock link is not removable. Pippin credits an engineer in SRAM’s Portugal facility for coming up with PowerLock and says, “the linking system is always the weakest link, but our 9-speed PowerLink is as strong as the surrounding links. We wanted to do the same with the connector link in our 10-speed chain, but because of the constraints of the narrow chain, we made it a permanent connection.”

It locks in by hand like the PowerLink, but if the rider wants to open the chain, he must do so at a different link and then install another PowerLock link to close it up again. The 1070 chain is the base model, the 1090 chain has hollow pins, and the 1090R also has hollow outer plates.

Other components?
Answering an obvious question, Ritzler says the company has no plans any time in the future to make hubs, wheelsets, pedals or headsets.

“We have a lot of areas in which we are industry leaders – suspension, shifting systems, brakes, and cranks and Truvativ offers stems, bars, and seatposts, and we have no plans to devote any of the company’s resources beyond those areas right now,” Ritzler notes. “The road group alone has required enormous resources as it is, and we would want to work on improving and refining those things we are already doing before taking something else on.”

The group also has no bar-end shifters as yet, so riders wanting shifters on the ends of aero bars will have to wait; the Kodak Gallery/Sierra Nevada team raced the time trials in the Tour of California on Campagnolo shifting systems. The company is working on this and is not saying when it will have filled this missing gap in the group.

Weight and Price
The Force group has a claimed weight of 2111 grams. Using the same seven components, Campagnolo Record weighs in at 1990 grams, Chorus comes in at 2200 and Shimano Dura-Ace scores 2180. SRAM has not formally listed weights for Rival components, but estimates that it should come in at around 2300 grams.

The suggest retail price for a complete Force group will be $1800, and Rival is forecast to come in at $1,200. It’s hard to compare complete group prices, since SRAM comes without the hubs and pedals often included in Shimano and Campagnolo group prices.

Riding it
I was fortunate enough to have the opportunity to take three long rides on the SRAM group in the hills and beach roads around Monterey before and during the Sea Otter Classic. I was doubly fortunate to ride with it on my own bike, even, since test ride bikes generally are not offered in 65cm frame sizes.

I found the feel of the lever shape to be quite comfortable, the brakes and crankset worked great, and the movement of the chain between cogs and chainrings was nice and smooth.

There is definitely a learning curve to the shifters, but after around eight hours on the bike I am as comfortable with the SRAM shifting system as I am with Ergo Power or STI. It took a while to untrain certain habits and to reinforce new ones. For example, when riding fast in a tight group after climbing a steep hill followed by an immediate curving descent on which one can only coast – like the Laguna Seca “Corkscrew” – I really want to confirm whether I am on the big chainring or not. In fast, tight conditions in a group, I am not as comfortable looking down to see what gear I am in as when riding alone, so I usually give a little push to the front upshift lever to feel if it is firm, indicating the chain is on the big ring. Do that on a SRAM lever and, if you’re already on the big ring, the chain drops to the inner ring. Eventually, I got used to pushing the lever fully and holding it there to ensure that I was on the big ring.

On rear downshifts, I had to turn off my mind and shift like I would with a Campy lever. When needing to downshift on a hill in a group that is going hard, I tended to push the lever too far, since I wanted to make sure I did not accidentally shift up a gear instead. The result was that either I would downshift two cogs, or I would push the chain inward a cog-and-a-half, so it would go partway up toward the second cog in a double shift and then drop back down into the gear I had intended with a clunk when I released the lever.

However, it actually shifts one gear at a time just fine if you just give it a standard, firm shift like you would with a Campy lever. Eventually, I got used to it and always hit the gear I wanted, but in a group or race situation, without a gear indicator and a difficulty to look back at the rear cogs, you might not know for sure. Riding alone or in a small group where it is no problem taking the attention away from the wheel ahead to look down at the cogs or chainrings, there is never a problem with this group. Shifts are fast, smooth and sure.

A brave new world
It not only looks like the two-party system in road components may be over, but that the SRAM group is no Nader-like spoiler only thwarting the chances of one to the benefit of the other. SRAM looks poised to take market share from both Shimano and Campagnolo, selling to those looking for another option as well as those seeking the lightest weight and/or highest performance.

The commitment on SRAM’s part to pull this off is enormous. The bike industry in general has a very low barrier to entry, but that is definitely not the case in the road drivetrain. There are large, tough competitors in place in that niche with long histories and great reluctance to cede any territory. But it looks like they will need to make way, whether they like it or not.

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