I am always swapping or changing parts around on my bikes, to try out different setups and components. The latest setup on the Focus Paralane all-weather commuting road bike is the 2x12 speed Dura-Ace Di2 groupset.
After that, I changed the left crankarm to the 105 R7000 4iiii power meter, followed by testing the Garmin Rally XC200 power meter pedals.
Now, I will change the rear disc rotor from 160 mm to a smaller 140 mm diameter. It will be the same XTR MT900 rotors, just in a smaller size. Reason is to common the rotor size with another upcoming bike, the Specialized S-Works Aethos, so that I can swap wheels easily if both have a 140 mm rear rotor diameter.
XTR MT900 rotor, in 140 mm diameter. I have previously used a 140 mm rotor on the Fnhon DB12 folding bike.
Diameter and minimum safe thickness specified here.
140 mm and 160 mm rotors side by side. Both have similar 4 arm aluminium spiders.
160 mm rotor weighs 106 grams, excluding the aluminium lock ring which weighs 8 grams.
140 mm rotor is lighter at just 88 grams. Downsizing saves 18 grams.
140 mm rotor installed on the Dura-Ace C50 wheelset.
Although downsizing the rotor from 160 mm to 140 mm means lower braking power (about 12% less), I don't think it would be a problem for me. There was always more than enough braking power, especially at the rear. During emergency braking, it is easy to lock up the rear wheel, unless I manage to modulate the rear brake carefully. Therefore, a smaller rear rotor will not really reduce the braking performance in my case, since the rear has more than sufficient braking power.
Without the rear brake adapter, the Dura-Ace brake caliper mounts directly to the frame for 140 mm rotors.
Without the rear brake adapter, these parts can be removed, saving another 17 grams.
In total, downsizing the rear rotor from 160 mm to 140 mm saves 35 grams, since both the smaller rotor and elimination of the rear brake adapter parts save weight. It is only 0.5% of the whole bike weight, if your bike weighs 7 kg.
As mentioned earlier, downsizing the rotor on the Focus Paralane is not to save weight, but rather to common the rotor size with another bike, where low weight is a key consideration there.
Another view of the Dura-Ace R9270 brake caliper on the Focus Paralane.
140 mm MT900 rotor! Also note the Robert Axle Project thru axles.
Here is the latest bike component specifications, which changes quite often.
With the latest changes, the Focus Paralane weighs 7 kg without pedals, which is a very competitive weight for a disc brake road bike. Compared to my other full sized bikes, it is lightweight indeed.
Latest/last bike spec, without pedals:
Canyon Endurace: 7.6 kg (gravel spec) - Bike already sold
Fabike C3: 8.1 kg (chain drive spec) - Bike already sold
Fabike C3: 9.0 kg (belt drive spec) - Bike already sold
Avanti Inc 3: 10.9 kg (belt drive spec) - Bike already sold
Adding the weight of the XTR M9120 pedals and SKS Bluemels mudguards, the weight becomes 7.9 kg. The mudguards add quite a bit of weight, at just over half a kg. However, it is absolutely necessary for wet weather riding.
For an all-weather commuting road bike, it really doesn't get much lighter than this, unless you are willing to sacrifice some features, such as removing mudguards (-500 grams) or converting to a front single drivetrain (-200 grams). The frame itself is also considered lightweight, as I have not found a lighter road bike frame with integrated mudguard mounts.
Very interesting article;)
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