The Sirius has been a staple in the Pipedream Cycles’ adventure bike line-up since its Titanium inception in 2012. Now a full custom-butted steel frame, the Pipedream Sirius S5 has evolved to cut a finer figure than ever, with new longer, slacker, steeper geometry.

We’ve heard it all before, but Pipedream have been on that particular band wagon longer than most; check out the original Moxie for example. Let’s take a closer look at the latest evolution of their short-travel adventure bike; the Pipedream Sirius S5.

Pipedream Sirius S5

pipedream sirius s5 steel hardtail mountain bike vintage green 120mm travel fork

For this model year, the Pipedream Sirius S5 is optimized for a 100-120mm travel 29″ fork. Sliding dropouts mean you can run the frame as a 29er, 27.5″ or in a mullet configuration. A departure from standard frame size nomenclature, Pipedream will offer the Sirius in Longish, Long and Longer, with reach spanning 445mm to 485mm. 

Maintaining that 64mm bottom bracket drop, the Sirius S5 goes 2° slacker at the head tube and a whopping 3.5° steeper in the seat tube, as compared to its 2018 4G iteration. That gives a HA of 65° and a SA of 77.5°.

pipedream sirius sligind dropouts 16mm chainstay length adjustment 27.5" or 29" or mullet

The Pipedream Sirius S5 is a very versatile steel hardtail. Those sliding dropouts at the rear allow for 16mm of chainstay length adjustment spanning a 425mm to 441mm range. It means the bike will take a 27.5″, 27.5+ or 29″ wheel out back, with ample clearance for a 29″ x 2.6″ tire. 

new sirius hardtail mtb from pipedream cycles

Though optimized for a 29″ fork, the Sirius S5 frame is also compatible with a 120mm-140mm 27.5″ fork. Those who see this bike as more of a downcountry shredder than an adventure bike might opt for that longer travel, smaller wheel configuration.

At the other end of the spectrum, Pipedream do plan on offering a rigid fork made specifically for the Sirius S5. Rumor has it that a flat mount dropout insert/slider will be available soon for non-drive side, so you can run a drop bar. Monster cross? Adventure gravel? Call it what you want. 

2020 pipedream sirius s5 geometry figures reach head seat angle longish long longer frame sizes
Pipedream reckon the Longish to Longer frame sizes will cover rider heights of 4’11” to 6’2” (1.5-1.88m)

Sirius S5 Frame Details

pipedream cycles sirius s5 adventure bike steel hardtail mountain bike short travel

As with all Pipedream Cycles’ steel frame mountain bikes, the new Sirius S5 gets a custom-butted tube set making for a clean gusset-less finish. The tubes themselves are composed of heat-treated CrMo 4130 steel. Short “dropper optimized” seat tubes mean riders should be able to run super long travel dropper seat posts.

2020 pipedream sirius bottom bracket yoke cnc machined compliance weight savings

The BB Yoke area is CNC machined to introduce a bit of compliance into the frame while saving a little on weight at the same time. Cable routing is external for ease of maintenance.

pipedream sirius frame details bottle bosses downtube seat tube bend

One set of bottle bosses on the downtube will limit the bike’s potential as a bikepacking rig. That said, the rigid fork that’s coming should go a long way to rectifying that…

Pipedream Sirius Rigid Fork (SRS48)

The new rigid fork will measure 482mm axle to crown and will be compatible with 27.5″ and 29″ tires, with clearance for a 3.0″ on the latter. It is a double-butted CrMo steel fork with a straight steerer tube. It will run a boost 110mm x 15mm axle and feature a 180mm post mount for the front brake.

pipedream sirius rigid fork rack fender mounts for bikepacking
Pipedream are offering a rigid fork for the Sirius for those who have their heart set on bikepacking missions

The fork will have a 47mm offset. Two versions will be available; one with multiple bosses for bottle or load-carrying cages, and one without. The latter would still take a small porteur rack without eyes. Both have received ED corrosion resistance treatment and come in gloss black only.

Pricing & Availability

2020 pipedream sirius steel hardtail mountain bike sliding dropouts 29er 27.5" or plus sized tires 3.0" maximum clearance

The new Pipedream Sirius S5 will set you back £649.00, frame only. Get it in longish, long or longer finished with the Silver Fox, Starry Night or Vintage Green colorway. The optional SRS48 rigid fork will set you back £129 – it is available for pre-order now but there’s a wait time of 4 weeks.

PipedreamCycles.com

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