Isaac Sonic

Super-stiff Newtonian masterpiece blends sane weight and terrific handling

You can trust Cyclingnews Our experts spend countless hours testing cycling tech and will always share honest, unbiased advice to help you choose. Find out more about how we test.

Isaac is a German company both in origin and philosophy:

The Isaac Sonic impresses you right out of the box with

Our 57cm sample came

Total as-tested

The presentation leads to one overwhelming expectation: this

Ride & handling: total stiffness

The Sonic’s overall ride is one of the stiffest I’ve ever

Heading uphill, the bike felt rock solid and light while

On most bikes a bit of bottom bracket flex almost seems to

The solution was to go to a bigger gear and stay on the

The Sonic’s giant front end also provided very precise and

Not surprisingly, the combination of the high drivetrain and

But how is all of this stiffness on rough roads, you ask? The

Even so, few will ever describe this bike as ‘plush’ but the

In short, the stiffness of the Sonic is such a huge

Frame: go big

These days there are a number of sub-900g frames (and even

The Sonic’s extra-large tubing sizes and joints results in a

Isaac’s hand-laid carbon frames proudly bear the technical

The frame is first molded in three sections (front triangle,

 Isaac also constructs

One small niggle with the frame was that the downtube cable

The front derailleur cable needs to run up though a small

To be fair, Isaac isn’t the only company to do such a thing

Equipment: Italian form & function

A bike is more than just a frame and fork, and as a mechanic

The dual-pivot front/single-pivot rear arrangement on the

The Campagnolo Neutron Ultra wheels were a pleasant surprise

One last observation on the wheels is that the Neutron Ultra

The Veloflex ‘open tubular’ tyres have their roots deep in

The supplied Deda Newton oversized bar and stem are ProTour

The Isaac carbon seatpost was nicely crafted and lightweight

Summary: benefits of not being the lightest kid on the block

The Sonic is a super stiff, precise and confidence inspiring

Rock solid and race ready with the complete Italian parts

Thank you for reading 5 articles in the past 30 days*

Join now for unlimited access

Enjoy your first month for just £1 / $1 / €1

*Read any 5 articles for free in each 30-day period, this automatically resets

After your trial you will be billed £4.99 $7.99 €5.99 per month, cancel anytime. Or sign up for one year for just £49 $79 €59

Join now for unlimited access

Try your first month for just £1 / $1 / €1