Torque-multiplying crankset promises cyclists more bang for their buck
On a regular bicycle crankset, the chainrings turn in a 1:1 ratio with the crank arms. In the case of the Ultime Ti crankset from French company MG Tech, however, things are a little different – an integrated planetary gear system actually turns the chainrings faster than the crank, reportedly allowing cyclists to deliver more torque at a given cadence.
Some readers may recall Truvativ/SRAM's similar (and now discontinued) HammerSchmidt 2-speed crankset. Riders could use its planetary gearing system to pedal at a 1:1.6 ratio, or they could disengage that system and go with the traditional 1:1.
There's also a lesser-known 3-speed crankset made by Poland's Efneo, with a planetary gearing system that allows riders to switch between 1:1, 1:43 and 1:1.79 ratios.
The folks at MG Tech, however, chose to keep things lighter and simpler.
Initially developed by founder Bernard Git, their Ultime Ti is permanently set to a single 1:1.44 ratio, and is equipped with two chainrings that are shifted between in the regular fashion. Because the system is a claimed 10.8 percent more efficient than a regular crankset at delivering torque, though, smaller (and thus stiffer and lighter) chainrings can reportedly be used to deliver the same performance as proportionally larger ones.
Additionally – and more importantly – the company states that riders should be able to go faster with same amount of effort, or maintain a given speed with less effort. All you engineers out there, please feel free to share your thoughts on the veracity of that claim, in this article's comments section.
"Determining the ideal ratio of the planetary is where the magic is in order to deliver the most efficiency for the rider," MG Tech's Dominique Anderson tells us. "If the gear is too low, there is no advantage. If the gear is too large, it becomes too difficult for the rider to turn such a large gear."
He says that the whole system – including bottom bracket adapter, bottom bracket, crankset and the buyer's choice of chainrings – tips the scales at about 1,150 grams, which is reportedly 400 grams less than the HammerSchmidt.
Ultime Ti is designed for use on all types of bikes, and is currently the subject of a Kickstarter campaign. A pledge of €569 (about US$663) will get you a crankset, when and if they reach production. And in case you're wondering about the "Ti" in the name, the axle is titanium, but the cranks are aluminum.
Update (July 24, 2018): We contacted MG Tech for more information on the Ultime Ti to address the concerns raised by our readers and Dominique Anderson from the company responded as follows:
As an experienced rider, bike mechanic, and mechanical engineering, I have ridden these cranks for some time and my experience is factual. I don't have the strength to turn over a 53x12 riding up an 8% grade over 700 meters as do some of my slogger friends. I stall.
I was laughing up a hill the first time I rode the Ultime cranks at 36rpm in the equivalent to a 53x12, just turning over the gear smoothly. Then with 100 meters to go to the top, accelerated steadily while seated. Never could I do that without the Ultime cranks.
With our cranks the additional leverage is a result from using smaller chainrings. With the planetary gear - that is not too big nor too small - we provide that additional leverage (thus more torque) using an equivalent overall gear development that is consistent with range of cassettes and chainrings available today.
Thus, cadence is by choice of the cyclists with our Ultime cranks, just as any cranks today. One can spin at 30 rpm, 70rpm, or 120 rpm and higher - just change gear like usual. But each gear is available through the cranks with constant and greater leverage.
We are preparing results using a basic engineering test with an inline scale connected to the chain on one end and to the other side of the crank, a simple weight. We compare results for standard Campagnolo crank with a 53 chainring versus an earlier version of the MG Tech Ultime (the planetary gear system being equal to today's version, the cosmetics and assembly simplified in the latest version).
The leverage is what is clearly illustrated, with a measurable gain each time for the Ultime crankset.
We will finalise numbers and photos to share with you and your audience in the next day.
Plus, have a look at the 90 tooth chainring on the bike attached ridden by Serge Perroud. Only with the Ultime cranks could Serge start from zero on his own to get up to speed. With standard cranks, he required assistance to get going.