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NAHBS 2013: 670g Guru Photon HL

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Guru's new Photon HL supposedly weighs less than 670g in a 54cm size.

Guru's new Photon HL supposedly weighs less than 670g in a 54cm size. (Image credit: Jonny Irick)
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Guru also showed off this eye-catching townie, based on the current Sidero-T touring frame. The complete model is likely to be green-lighted for production and will probably be called the Uptown.

Guru also showed off this eye-catching townie, based on the current Sidero-T touring frame. The complete model is likely to be green-lighted for production and will probably be called the Uptown. (Image credit: Jonny Irick)
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Guru's fully custom division is called Guru Cycleworks. Dream it up and it can probably be done.

Guru's fully custom division is called Guru Cycleworks. Dream it up and it can probably be done. (Image credit: Jonny Irick)
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Guru's top-end titanium road bike, the Praemio-R, remains unchanged for 2013.

Guru's top-end titanium road bike, the Praemio-R, remains unchanged for 2013. (Image credit: Jonny Irick)
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The Guru Praemio-R features a 44mm head tube that can be used with either straight or tapered steerers.

The Guru Praemio-R features a 44mm head tube that can be used with either straight or tapered steerers. (Image credit: Jonny Irick)
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The fantastic titanium dropout on the Guru Praemio-R.

The fantastic titanium dropout on the Guru Praemio-R. (Image credit: Jonny Irick)
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Guru built this 650b/27.5" stainless steel hardtail from Columbus XCR tubing for a dealer.

Guru built this 650b/27.5" stainless steel hardtail from Columbus XCR tubing for a dealer. (Image credit: Jonny Irick)
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Polished and masked details really make this Guru XC275 pop.

Polished and masked details really make this Guru XC275 pop. (Image credit: Jonny Irick)
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Guru augmented its standard Sidero CX steel cyclocross bike with disc tabs front and rear - plus this beautiful paint job.

Guru augmented its standard Sidero CX steel cyclocross bike with disc tabs front and rear - plus this beautiful paint job. (Image credit: Jonny Irick)
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The front end features a 44mm head tube and tapered Enve Composites disc 'cross fork.

The front end features a 44mm head tube and tapered Enve Composites disc 'cross fork. (Image credit: Jonny Irick)
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A short reinforcing strut is used on the back end of Guru's disc-equipped Sidero CX 'cross bike.

A short reinforcing strut is used on the back end of Guru's disc-equipped Sidero CX 'cross bike. (Image credit: Jonny Irick)
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Beautiful paint work on this Guru Sidero CX.

Beautiful paint work on this Guru Sidero CX. (Image credit: Jonny Irick)
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Guru says that wrapping select areas of the new Photon HL with reinforcing bands of carbon fiber help increase its strength while reducing weight.

Guru says that wrapping select areas of the new Photon HL with reinforcing bands of carbon fiber help increase its strength while reducing weight. (Image credit: Jonny Irick)
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The previous Guru Photon used essentially round tubing. New Photons switch to a more squared-off profile.

The previous Guru Photon used essentially round tubing. New Photons switch to a more squared-off profile. (Image credit: Jonny Irick)
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While the other Guru Photon models use a PressFit 30 bottom bracket, the stiffer Photon R gets a wider PF86 shell.

While the other Guru Photon models use a PressFit 30 bottom bracket, the stiffer Photon R gets a wider PF86 shell. (Image credit: Jonny Irick)
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Chain stays are bigger on the Guru Photon R, too.

Chain stays are bigger on the Guru Photon R, too. (Image credit: Jonny Irick)
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The seat stays are about the same as on the Photon SL and HL models but the seatpost bumps up to a 31.6mm diameter on the Photon R.

The seat stays are about the same as on the Photon SL and HL models but the seatpost bumps up to a 31.6mm diameter on the Photon R. (Image credit: Jonny Irick)
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One of the key features of the new Guru Photon HL are these strips of alternating-modulus carbon fiber, which Guru's Phil Pinsky describes as "built-in ribs" for additional structural support and stiffness.

One of the key features of the new Guru Photon HL are these strips of alternating-modulus carbon fiber, which Guru's Phil Pinsky describes as "built-in ribs" for additional structural support and stiffness. (Image credit: Jonny Irick)
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The seat stays are fairly slim on the new Guru Photon HL but this frame was primarily designed for light weight, not comfort.

The seat stays are fairly slim on the new Guru Photon HL but this frame was primarily designed for light weight, not comfort. (Image credit: Jonny Irick)
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The thick machined aluminum rear derailleur hanger is bolted to a carbon fiber dropout.

The thick machined aluminum rear derailleur hanger is bolted to a carbon fiber dropout. (Image credit: Jonny Irick)
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Guru sticks with a a straight 1 1/8" steerer on the Photon HL because it's lighter than a tapered one.

Guru sticks with a a straight 1 1/8" steerer on the Photon HL because it's lighter than a tapered one. (Image credit: Jonny Irick)
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Guru says it invented the superlight category with the original Photon and now it's pushing the envelope even further with "hyperlight".

Guru says it invented the superlight category with the original Photon and now it's pushing the envelope even further with "hyperlight". (Image credit: Jonny Irick)
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Helping the Guru Photon HL show bike stay under the 5kg (11lb) mark are THM-Carbones Clavicula cranks fitted with KCNC chainrings.

Helping the Guru Photon HL show bike stay under the 5kg (11lb) mark are THM-Carbones Clavicula cranks fitted with KCNC chainrings. (Image credit: Jonny Irick)
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The internal routing system can be used with either mechanical or electronic drivetrains. Housing stops are carbon fiber, too.

The internal routing system can be used with either mechanical or electronic drivetrains. Housing stops are carbon fiber, too. (Image credit: Jonny Irick)
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Guru's previous Photon now morphs into a three-bike range, including the new Photon SL. Still extremely light at under 750g for a 54cm frame (claimed), this model is said to be the most comfortable of the three and also features a slightly taller head tube on stock models.

Guru's previous Photon now morphs into a three-bike range, including the new Photon SL. Still extremely light at under 750g for a 54cm frame (claimed), this model is said to be the most comfortable of the three and also features a slightly taller head tube on stock models. (Image credit: Jonny Irick)
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The Photon SL uses the same tube shapes as the Photon HL but lower modulus tubing. The circumferential strips of reinforcing carbon around the top tube, down tube, and chain stays are omitted, too.

The Photon SL uses the same tube shapes as the Photon HL but lower modulus tubing. The circumferential strips of reinforcing carbon around the top tube, down tube, and chain stays are omitted, too. (Image credit: Jonny Irick)
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The new Guru Photon SL (pictured) and HL both use standard 27.2mm seatposts.

The new Guru Photon SL (pictured) and HL both use standard 27.2mm seatposts. (Image credit: Jonny Irick)
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As on the top-end Photon HL, the new Guru Photon SL uses a straight 1 1/8" head tube.

As on the top-end Photon HL, the new Guru Photon SL uses a straight 1 1/8" head tube. (Image credit: Jonny Irick)
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Guru says the new Photon R is the most racing-specific of the new three-bike Photon range with a sub-800g claimed weight (54cm frame) but more stiffness than the other two.

Guru says the new Photon R is the most racing-specific of the new three-bike Photon range with a sub-800g claimed weight (54cm frame) but more stiffness than the other two. (Image credit: Jonny Irick)
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The Guru Photon R uses a tapered 1 1/8-to-1 1/2" front end with an Enve Composites 2.0 Road fork.

The Guru Photon R uses a tapered 1 1/8-to-1 1/2" front end with an Enve Composites 2.0 Road fork. (Image credit: Jonny Irick)
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This case summarizes some of the custom possibilities with Guru.

This case summarizes some of the custom possibilities with Guru. (Image credit: Jonny Irick)

This article originally published on BikeRadar

Guru marketing director Phil Pinsky says his company invented the 'superlight' road bike category with the original, 750g Photon. Now he says Guru is inventing the 'hyperlight' category with the new, sub-670g (claimed, 54cm) Photon HL.

Guru has switched from the original Photon's essentially round tube shapes to a more squared-off profile. As with other companies that have moved to similar shapes, Pinsky says it's a more efficient profile that allowed Guru frame designers to trim weight without affecting strength on the tube-to-tube carbon fiber frame.

"Squaring it off gives you a good extra inch of carbon fiber width holding the tubes together," he told BikeRadar. "That allows you to strip out a ton of superfluous material. You don't need seven layers of material if you've got a lot of width."

Adding further reinforcement are strips of carbon fiber added circumferentially at high-stress areas such as the front of the top tube, the front of the down tube, and the chain stays. "It's almost like built-in ribs," said Pinsky.

Other weight-saving concessions include a PressFit 30 bottom bracket shell with a carbon fiber sleeve, a straight 1 1/8in head tube (Guru includes an Enve Composites 1.0 Road fork), carbon fiber housing stops and headset bearing seats, and carbon fiber dropouts. The internal routing is readily convertible between mechanical and electronic drivetrains, too.

According to Pinsky, the Photon HL surpasses the original Photon in terms of stiffness-to-weight, although it sounds like the original one was a touch stiffer overall.

Pinsky says the Photon HL has a 91kg (200lb) rider weight limit and the custom-only frame will be available around the end of April. Suggested retail price is $8,500 for the frame, fork, and headset.

Helping the Guru Photon HL show bike stay under the 5kg (11lb) mark are THM-Carbones Clavicula cranks fitted with KCNC chainrings.

Photon family grows to three

Guru will supplement the top-end Photon HL with two other new Photon frames as well.

The Photon SL features the same tube shapes, straight 1 1/8" front end, PressFit 30 shell, and convertible cable routing as the HL but with a different lay-up and carbon fiber content that bumps the weight up to a still-light sub-750g (claimed) for a 54cm size. Pinsky says this is the most comfortable of the three Photon models and with a slightly taller "Fast Forward Flex" geometry on stock frames (up to 1.5cm depending on size), it's aimed more at fast enthusiast riders.

"It's halfway between our race and endurance geometries so it give you the flexibility to go either way."

Retail price for stock Photon SL frameset is $4,500 and Pinsky says it will be available at the end of March. Custom versions will cost $5,500.

Rounding out the Photon trio is the new Photon R, aimed at racers who value stiffness above all else. The Photon R uses squared-off tube profiles like the other Photon models but the diameters are bigger all around. Guru also gives this model a tapered 1 1/8-to-1 1/2in front end and wider PF86 bottom bracket shell. Seatpost diameter bumps up to 31.6mm, too.

According to Guru, the Photon R is a substantial 30 percent stiffer at the bottom bracket and in torsion than the original Photon while still weighing less than 800g (claimed, 54cm frame) and retaining the same ride quality.

The Photon R will also be available around the end of March and suggested retail price is $5,500 for the frame, Enve Composites 2.0 fork, and headset in stock geometries. Full custom geometry will add another $1,000.

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