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Review: Wren Sports’ ultralight aluminum stem is scary light (for a reason)

Wren Sports aluminum stem, feature img
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Wren Sports aluminum stem, action shot

It’s always nice to shave a few grams off your bike, but there is definitely a strategic way to go about saving weight while maintaining strength in the right places. For the weight weenies among us, Wren Sports (not to be confused with the UK’s Wren Bicycles) has produced one seriously lightweight stem, which they recommend for anything from road to MTB riding.

We received a selection of the new stems in the shortest sizes, and I volunteered to try out their 50mm model on my all-mountain bike while Zach used one for his recent Otso build. When it arrived I got a bit nervous. This thing is paper thin, uses tiny hardware and felt about as heavy as an empty soda can. Despite those initial concerns I hit the trails and after some apprehensive test laps I gained the confidence to ride full-tilt.

At the end of the test period both stems are still in one piece, though Wren did make one small (but much appreciated) change. Check out the full review and actual weights below…

Wren Sports aluminum stem, side

Wren Sports’ alloy stems feature a 1-1/8″ steerer clamp, 31.8mm bar clamp, and come in seven lengths ranging from 40-100mm. They are available with either a 6° or 17° rise (all of ours were the 6° models). With a 50mm stem weighing just 75g, you’re probably wondering if there’s something special about its construction. Wren Sports’ stems are made from AL7050 aluminum, and are 3-D forged in specially designed molds to strengthen the metal by enhancing its grain structure. The company claims this process is superior to CNC machining.

Wren Sports aluminum stem, front

Upon installation, I found out the stem’s tiny hardware requires a T-20 torx bit. Since I’m running a carbon handlebar, I was at my local shop borrowing their torque wrench and finding a T-20 bit and the necessary adapters was a hassle. Obviously weight was the primary concern, but I think it would have been worth a few extra grams to stick with the far more commonly used T-25.

The good news – Wren has already decided to make a running change to T25 torx bolts instead of the tiny T20s.

Wren Sports aluminum stem, rear

I would be lying if I said I didn’t worry about the strength of the stem. Saving weight is great, but a stem is not where you want to take chances with durability. Since my local trails (Whistler and Pemberton) are a lot more ‘enduro’ than XC, I was concerned enough to ride with a T-20 and a spare stem in my pack.

After installation the only adjustment I had to make was tightening the steer tube bolts before my first descent. With such thin aluminum I was afraid to over tighten these bolts at the shop, but a short climb confirmed they weren’t tight enough. With my trailside tools I can’t tell you how much torque I put on the bolts but once snugged up they held the stem tight for the rest of my test period.

Wren Sports aluminum stem, top

This is an odd review to write, because the bottom line is that I had no issues whatsoever with the stem aside from the impending fear that it might fail – but it’s been holding strong since mid-June! Despite this, I’m still removing it from my AM bike because I can’t shake the feeling that I’m tempting fate. The stem isn’t going into retirement, however – I think I’ll enjoy the weight savings on my commuter bike.

Wren Sports aluminum stem, actual weight

For those riding less technical, mellower terrain this stem could be a great way to drop some weight off your 100mm XC bike. For charging down rougher trails on 160mm enduro machines it seems a bit too light-duty, and even if it’s all in my head I’d rather not take the chance of overriding this ultralight stem. The Wren Sports alloy stems come in gloss black and sell for $59.99 USD.

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Zach’s Take:

When the Wren Stems came in, I was in the middle of piecing together my recent Otso Voytek build. I wasn’t quite sure what length stem I needed, so it was nice to have a selection to pull from. Ultimately, I ended up going with the 50mm (center) rather than the 40mm that I started with or the 60mm. That combined with the longer reach of the medium Voytek proved to be the magic number. For what it’s worth, all of the stems measured within 1-2g of the claimed weights on the Wren site. Not bad.

To get right to the point, in my opinion T20 bolts just don’t cut it. Fortunately, Wren seems to agree. Before I had even voiced my concerns, they (claimed) they had already made a running change to T25 Torx bolts. However, their website still lists the stems as having a T20 Torx bolt.

I will say though, that once I got the stem settled in it performed admirably for such a light weight. It never felt flexy, though I probably never pushed it past the “aggressive trail” segment in terms of riding. I’d agree that riders really pushing the limits of enduro may want to go with something more burly (though they are certified for Mountain/Enduro use for ISO purposes), but for XC, Trail, and other users looking for a super light stem that is also super affordable, the Wren is worth a look broken.

Update: After a two seasons of use, the Wren stem I was using on the Otso above failed after one of the steerer clamp bolts pulled out the threads. This did not happen while tightening the bolt, it just popped while riding the bike allowing the stem to rotate. Fortunately, it was while riding the bike in a parking lot at the trailhead, so I didn’t have far to walk (and I just happened to have a replacement stem in the car).

This was still with the T20 Torx bolts, but as noted Wren still lists the stem with T20 hardware on their site. But based on my experience with this stem, I cannot recommend it. More so, if you have one on your bike currently, I’d recommend replacing it with something else as soon as possible.

wrensports.com

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21 Comments
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Christian Samuelsen
6 years ago

Steve: you wrote “…made from AL7050 aluminum, and are 3-D forged. The company claims this process is superior to CNC machining.”

For clarity: it is metallurgical _fact_ that forging is superior to machining for grain structure and strength given two identical or near identical examples and both fabricated into the same shape through the two different methods. Machining, whether by hand, manual or CNC will _always_ result in a weaker end product, because the grain structure of the metal is untouched. More so with aluminum because of some of its physical properties.

And no, I have not yet had my first coffee, my breakfast is getting cold and I may be a bit petulant because of that….

Ol'shel'
Ol'shel'
6 years ago

It has held up for over 4 months!

mudtrout
mudtrout
6 years ago

“Since I’m running a carbon handlebar, I was at my local shop borrowing their torque wrench and finding a T-20 bit and the necessary adapters was a hassle. Obviously weight was the primary concern, but I think it would have been worth a few extra grams to stick with the far more commonly used T-25.”

Bummer your local shop doesn’t have basic tools…

bbb
bbb
6 years ago
Reply to  mudtrout

…or they have too many regulars, mates and other people who shouldn’t be in the workshop, borrowing (loosing) tools… 😉

…from experience…

me
me
6 years ago

shame on Extralite for making almost equivalent weight range stems but 4 times the price of these.

Klaster_1
6 years ago
Reply to  me

Too bad the article mentions weights for longer stems exactly nowhere. I won’t be surprised if the product is more on par with kalloy uno than the hyperstem.

Me
Me
6 years ago
Reply to  Klaster_1

Don’t me lazy and go on their website.

me
me
6 years ago

So looks like the bolts are Steel correct? well…the perfect upgrade for this stem is going with Proti Fully Titanium Bolts – http://www.proti-bicycles.com. Since the stem is 3d Forged….it needs to have forged Ti bolts!

Bikomio
Bikomio
6 years ago

please do not compare this to extralite. Extralite makes their products in house. And they have been around for decades…

Me
Me
6 years ago
Reply to  Bikomio

In house and for decades…pretty story and everything but if 3D forging is proven to be better than machining, Extralite have two options: either they upgrade their manufacturing process to something superior such as forging…or lower their prices…if not I will have all my attention to this company Wren in question. If someone insist with extralite is purely a show off move.

VeloKitty
VeloKitty
6 years ago

These look pretty good. There is also the KAlloy Uno and Aerozine XS7 for about the same weight and price.

Lifetime Biker
Lifetime Biker
6 years ago

If your truly interested in saving weight: loose the waterpack (camelback, osprey, whoever), loose the overloaded seat bag. Biggest weight saving…..loose 5 pounds of bodyweight. I find it funny people get obsessively anal about saving grams on their bikes, when they could loose POUNDS off their bodies (I’ve got easily 10 extra myself)

thesteve4761
thesteve4761
6 years ago

How’s a spare stem in your pack going to protect your face if the stem fails?

Veganpotter
Veganpotter
6 years ago

I don’t know why they bother advertising to the roadies? Unless you’re riding a very small bike, you shouldn’t have anything as short as their longest stem…unless your bike doesn’t fit you.

Dominic
Dominic
6 years ago
Reply to  Veganpotter

Their road one (you can tell by the fact that it comes in -17º) comes in 80, 90 and 100. I don’t know about you, but those are pretty solid choices. Having fit a lot of people in my time, most people who need a fit out of the box aren’t going to be very comfortable as far over the front wheel as a pro is with his 140.

Brian
Brian
6 years ago

Especially for smaller riders, these lengths are very useful and the 100mm is pretty mainstream for average sized riders.

Brian Nystrom
Brian Nystrom
6 years ago

Also, the reasonable price will appeal to a broader market, making them even more applicable.

Huuhh
Huuhh
6 years ago

Just using Torx heads of any size is stupid. They offer no advantage to the consumer in any application compared to Allen heads, on the contrary (more tools needed). They are sometimes useful for large scale assembly, but making stems isn’t anything like that.

Darryl Duck
6 years ago

Torx heads are far more resistant to stripping out, especially in smaller sizes where hex heads are pretty useless.
Unless you are dialing your fit during a number rides, there is no need to ever touch stem bolts on a ride.

Aaron
Aaron
6 years ago
Reply to  Darryl Duck

So you’ve never twisted your bars after falling off your bike?

Brian
Brian
3 years ago

I know its an old thread, but i just got my 100mm stem(86g) from the states(i live in south africa)..waited a month for the damn thing(our local post office is pathetic)..im doing a light build, its still a work in process so as soon as the bike is complete i’ll put the stem through its paces..

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