Wit their patented Z-shaped Ventum One triathlon bike and the UCI-legal NS1 all-rounder already turning heads, Ventum introduced the GS1 gravel bike. With aerodynamic touches and a tidy and efficient frame, the GS1 is made for gravel speed. Dressed up in a SRAM Rival/GX AXS 1x mullet kit, this GS1 has been happily racking up the miles this summer across Utah, Colorado and Oklahoma.
Ventum GS1 Features:
- Carbon frame with aero shapes for added efficiency
- Internal routing through the head tube
- Optimized layup for durability and efficiency
- D-shaped carbon seatpost for added comfort
- Bottle mounts plus bento and underside mounts
- Dual-offset fork for either 45 or 50mm offset (not tested yet)
- 1x or 2x compatible with covers to keep things clean
- T47 threaded bottom bracket
- 700x42c or 650x48c clearance
- 19.3 lbs (M/L, as tested with Zipp 303s wheels and Rival/GX AXS)
- Lifetime frame warranty
- MSRP: Starting at $4199 (Rival AXS XPLR)
A gravel bike made for everything
I think it’s about time we started calling gravel bikes, plain old “bikes.” I mean come on… it’s just a bike at this point and I happen to ride it everywhere (road, gravel, singletrack, etc.). With that, the Ventum GS1 “bike” confidently handles all of the above in an affordable, clean package. Deliveries of the GS1 first started in December 2020, but, like every manufacturer, availability of parts kits has remained a moving target since then. Things are starting to improve, but it will remain a challenge well into 2022.
Looking at Ventum’s site, they do have the new SRAM Rival XPLR kits readily available with framesets to hang them on. With three available colors (nautical blue, lilac and vintage green), the green color was dubbed the most photographic, so that was selected for this review. And, it looks great! Overall frame quality is excellent with a clean aesthetic and durable paint job. As always, I added protective film under the downtube and other areas to protect against debris, tire rub and bike rack touch points.
The front derailleur mount wasn’t needed with the SRAM Rival/GX AXS 1x mullet kit, so, I kept the nice plastic cover in place . Additionally, the mechanical ports are also concealed by a second cover. That one sat loosely (even when tightened up), so I wedged a little electrical tape in there and it’s now snug.
Cable routing is clean, with the only exposure being from the end of the bar tape to the point of entry ahead of the headset. With only two cables, that makes for the cleanest possible look, but mechanical is still supported. If Di2 is in your future, you’ll have to go with the seatpost-style battery since the GS1 lacks a dedicated battery port in the downtube. While the GS1 does sport sufficient clearance at 700×42, having the dual chainstay drop typically affords larger clearance than 42 mm. And, with Zipp Tangente Course G40 tires mounted to Zipp 303s wheels, they measure out to 42 mm, which is as wide as I’d go. I can see evidence of just a little bit of tire rub on the fork, but it’s minimal.
Geometry (on paper) remains racy with the GS1, so don’t expect a tall stack here. On the M/L it’s 570 mm with 383 mm reach, which puts it at 10-20 mm lower stack than much of the competition. However, that 383 mm reach means that the effective stack with a 110 mm stem and a 71-degree head angle kind of evens itself out. With all that, the reality is I have the same 15mm spacer under the stem as I do on the Open UPPER and the fit is perfect. Ventum includes their zero-setback D-shaped post, but a setback post is available should you prefer. If you set your cleats all the way back (like I do), you will experience just a slight bit of toe overlap.
The Ventum GS1 arrives with the fork in 50 mm offset. Changing it to the shorter, 45 mm offset is a little more involved (new bolts and spacers are needed), so I haven’t yet tested it. I hope to dig into that further in the coming months, so stay tuned. With a short 420 mm rear center (chainstay length), this one remains nimble when you’re throwing it around. I’ll add that the the front caliper mount is a bit of an oddity. To run 160 rotors, you place the flat mount adapter in 140 mm mode (huh?). I actually ran a 180 mm front rotor for a couple of months in the 160 mm mode (but Ventum tells me that’s not recommended). So, yes, the flat mount adapter needs to be set up for 140’s to run 160’s. I don’t know if the tooling got messed up or what, but it’s only a head-scratcher on initial setup, then you don’t think about it.
The frame shapes do have an aero touch to them and the cable routing is tidy, but I wouldn’t call this a full-on aero bike. The aero tube shapes do aid in airflow, but it’s hard to measure that sort of thing under gravel conditions. I will give some kudos to the top tube shape as the curved underside does make for easy grabbing to carry the bike through rough sections or on/off the bike rack.
Let’s talk about gravel (dirt and road too)
Over the past four months, I’ve been able to throw just about everything possible at the GS1 and it really does do it all with style. My usual routes are mixed gravel, road and singletrack and I never shied away from any of it. Pedaling efficiency feels excellent with a responsive feel when laying down the power. Standing or sitting, I’m not feeling anything out of sorts with delivering power where it’s needed.
On my first two rides, I did suffer from seatpost slippage. After that second ride, I basically emptied an entire packet of carbon paste inside the seat tube and on the seatpost, then cranked that bolt down tight. In talking with another GS1 owner, that experience sounds common. Take my advice and empty a full packet of paste in there and tighten that bolt down or you could experience the wrong kind of dropper post.
Handling is solid overall with nothing significant to pick at. Occasionally, steering does feel a little slow, but some anticipation and familiarity with how the bike handles goes a long way. On the flip side of that, the GS1 is ultra stable at speeds. I feel very confident when ripping down straight gravel or road descents. Again, don’t expect razor-sharp handling on road descents. This became apparent when descending the Alpine Loop down the American Fork Canyon side. That initial descent on the road features lots of twists and turns and I couldn’t dance in/out of the corners like a road race bike (but I didn’t expect it to).
Rounding out the on-road performance of the GS1, I have no real beef riding it on the road. Further, I set it up with Bontrager Aeolus Pro 51’s mounted to Bontrager R3 32c tires and it rolls fast with segment times in the ballpark of what I’d expect on a 19 lb. gravel bike turned road racer. You won’t be nabbing PR’s, but a quick wheel change does a lot for your local road rides or winter training.
In addition, I spent a good portion of the summer riding the GS1 with 650b wheels. I’m a fan of the Specialized Pathfinder Pro 650×47 tires, so that setup was a natural choice — particularly as we headed to Oklahoma for some cowboy gravel adventures. In 650b mode, you can expect a little quicker handling and way more capability. Those low tire pressures and voluminous rubber makes for even more fun on rugged terrain. I could get into and out of the rough stuff, no problem. Some gravel bikes turn wonky with smaller wheels, but the GS1 feels great. In fact, I may prefer it with 650b’s.
Ahead of SBT GRVL 2021, I decided to switch back to the original 700c setup for a few reasons. The primary reason was to see which wheel size I liked best for the 100 mile blue course. Since I rode 650’s last time, it was time to go with the more traditional wheel size. Unless you are aiming for a podium finish, I’d rather go 650b, to be honest. After that long in the saddle, the extra comfort and confidence is worth it in my book. And, they roll just as fast (in spite of what you may think). Up until SBT GRVL, the internal cabling was silent, but something rattled loose on course and I now get a little bit of cable rattle when rolling over the roughest terrain.
On the steepest climbs, you need to stay on top of it because it wanders ever-so-slightly. But, it can climb anything your lungs can handle. It’s easy to find the sweet spot when standing or seated and I can always maintain proper traction, when needed. At slow speeds, it’s easy to remain balanced and it rides hands-free very confidently.
Sizing: I’m 5’11” and have a moderate fit, so I feel at home on 55-56 cm frames. The M/L fits perfectly with a 110 mm stem and a 15 mm stem spacer.
- A ton of value in this bike
- Clean look with classy color options
- Can tackle anything you can throw at it
- 650b mode feels natural and fun
- Flickable and fun on the trails
- Clean cable routing with easy fit adjustments if needed
- Uses standard bar/stem combo
- Rolls along efficiently for long days in the saddle
- Capable for gravel and singletrack and good on the road too
- Not as much tire clearance as a typical double chainstay drop bike
- Seatpost requires a ton of carbon paste to stay put
- Developed some cable rattle on the roughest terrain (could be the mechanic’s fault though)
- Handling is a little slow in 50 mm offset
The Bottom Line: Ventum GS1 Gravel Bike
Around home, I really can’t complain about the overall performance of the GS1. It’s fun to ride and handles as I would expect it to. There are faster gravel bikes out there and there are more nimble gravel bikes out there, but the Ventum GS1 straddles the middle of the spectrum quite well. And, the value for the money is off the charts. Supporting a smaller manufacturer always feels good and Ventum includes a lifetime warranty to boot!
Buy Now: Visit VentumRacing.com
Ventum only makes three bike models, so they are small and selective on what they can reasonably bring to the market. So, with the GS1, they have delivered a reliable and fun gravel bike that the bulk of riders will enjoy. It's not the fastest or the most rugged, but it handles everything you can throw at it. I intentionally built the GS1 with monster truck capabilities, using a Rival/GX AXS mullet build. With it, I can climb up anything and still have enough gears for road descents. I can confidently ride this bike anywhere and it doubles pretty well as a road bike.
Wondering if you tried any tires beyond the 700×42 range. I have an NS1, and I’ve really been considering getting a GS1, but I’d love to run a tire that measures out to 45mm. 42mm is such a narrow clearance these days.
700×42 is about as big as I would go. The chainstay gets tight. With 650×47’s, I got some light rubbing under extreme load as well. Yeah, it’s more of a race gravel bike. 700×45 would be really tight.
Thanks for the info!