What is the difference between rotor 3d and 3d

Quote Reply. Re: what model Rotor crankset do I have Post 2 of 9 views. You'll need a new BB with those as they are both 30mm spindles. Post 3 of 9 views. Post 4 of 9 views. Post 5 of 9 views. Post 6 of 9 views.

Bikepedia has your model bike running a BB1 bottom bracket. This is a 24mm diameter. The crank is listed as 3D, which supports this. Caveat, what's on your bike may be different. This info is based off five minutes on Google searching " P4 Rotor" and also looking at images.

Post 7 of 9 views. You can remove your crank with two allen wrenches. Measure the spindle. If it's 24mm, you have a 3d. JBF seems to support this. Post 8 of 9 views. Forum rules. Post by bruno on Wed Jun 01, am I decided to get me a Roto crank to loose some weight on my bike. Currently I'm running a Dura-Ace crank. Is there a big difference between both cranks? There is the weigth difference of 60gr according to the Rotor website. How much weight would I win with both cranks?

Post by sedluk on Wed Jun 01, pm I am surprised that you chose a Rotor crank if losing weight is a concern. They are nice cranks, look nice, probably stiff. But relatively heavy compared to just about any other expensive aftermarket crank. Don't know if your frame is bb30 compatible? It either is, or is not, it makes choosing a lot easier.. The oval chainrings are heavy since stiffness is important for these.

But with round chainrings, I think they're fairly light. Happy to be corrected though. Weight is g. Pretty porky. Post by sedluk on Thu Jun 02, am djconnel wrote: The crank is still lighter than Dura-Ace, right? The differences between the cranks are subtle but worth knowing. The 3D crankset is CNC machined, comes with a 24mm steel axle and weighs in at g mm length crank arms.

The 24mm axle means that it is compatible with standard bottom brackets from Shimano, FSA etc - see below for the full compatibility list. Most of the deflection undesired movement such as twisting or flexing comes from the axle twisting whilst pedalling. By using a 30mm spindle, Rotor and other manufacturers are able to use aluminium alloy, which because of the larger diameter tube is stronger and lighter. The result is less undesired twisting and therefore deflection and ultimately more power transferred to the wheels.

All three cranksets feature what Rotor call their 'Trinity Drilling System' which is a process that involves hollowing the cranks out by drilling three cylinders along each crank arm all the way from the axle to the pedal. Rotor claim that by removing the material in this way, the stiffness to weight ratio stays about the same. On the right you can see one of the round billets of aluminium alloy that Rotor start with on their CNC machined cranks and what it looks like after it has been machined.

So, with this detailed, yet worthwhile introduction out of the way, it's time to talk about the product in hand. Unlike most crankset manufacturers, Rotor sell most of their cranks and chainrings separately. This is good in the sense that you can choose the chain ring combination that best suits your style or type of riding, assuming you know what that is of course.

This is significant as each BCD places restrictions on the maximum or minimum size of the small chainring. The small chainring must have 38 teeth or less on the mm BCD crankset and must have 38 teeth or more usually 39 on the mm BCD crankset. BCD stands for Bolt Circle Diameter and is the diameter of the circle created by, in this case, the five holes at the end of the arms on the spider - the multi armed piece that connects the chainrings to the crankset.

The BCD number must be the same for both the crankset and the chainrings otherwise they won't be compatible. As mentioned you'll need a mm BCD crankset for this. For this you'll need a mm BCD crankset as covered earlier. On this setup the smaller chainring has just two more teeth than the small ring on a compact chainset yet the larger chainring only has one tooth less than the big chainring on a standard or double setup.

Interestingly on Shimano's latest 22 speed Dura-Ace FC chainset the BCD is the same on all cranks allowing you to run either a double or compact chainring combination. The larger toothed ring is big enough for keeping pace with the peloton if you're racing, yet the toothed 34 in our case smaller ring allows for higher cadence riding when on medium to steep climbs. This has included a few high tempo training rides where I've averaged mph during high intensity bursts as part of a group of four, taking it in turns on the front.

This simulated race pace was the perfect test for my speed SRAM Force setup with a tooth cassette see Cadence at Speed table on right for more details and I was pleased to find that I had more than enough gears to cope with any speed increases that the others threw at me. The racing I do early in will be the true test but I felt happy enough knowing that I still had a few gears left to call on.

The smaller toothed chainring has at times felt like a big step down in terms of pedalling and it's been hard to adjust my cadence smoothly in some situations when switching from the big ring to the small or vice versa. A toothed small ring would make this gap easier to bridge and will also offer more usable gears on the generally flatter terrain that makes up most of my riding. A toothed small chainring might even be a better option on seriously hilly terrain, particularly on long alpine ascents where you need to maintain a steady cadence uphill for an hour or more.

With top end groupsets mostly being speed it's good to know that the Rotor range of chainrings is compatible with these. The Rotor NoQ round Pro-Compact chainrings on our crankset features five lifting pins with machined ramping patterns to help move the chain smoothly and quickly.

To compare the Rotor 3DF to other cranks see the table below for comparable statistics. Working out bottom bracket and crankset compatibility can give you a headache but Rotor's system is straightforward once you've got your head round their naming convention. To the right is a table that helps you work out what system you need for your bike based on what frame you have and whether it accepts threaded or non-threaded bottom brackets.