Bike Check: Noel's Flat Bar Cache
Updated: Sep 25, 2020
How tall are you?
186cm / about 6' 1 1/4"
What size frame and how does it fit you?
Well, I designed the bike, so it fits me pretty damn well! I ride a 60cm Cache. For a drop bar build, I would run a 46cm wide gravel bar with a -6 degree stem. For a wider drop bar build (i.e. some of the newer 48cm and 50cm or a highly flared bars like the Spank Flare), I would reduce the stem length to 70mm.
For this flat bar build, the reduction in effective top tube length by moving from a drop bar to a flat bar with rearward sweep was the single biggest fitment challenge. More details on this below in the bar/stem build spec discussion.
What do you like most about it?
The bike is insanely fun. About as much fun as you can have on trails without bringing suspension into the mix! It’s an entirely different kind of technical riding. Obviously, you can ride a bike like this on some blue trails (and even harder trails if you’re a pro like Daniel Shaw!) but for most people, this build is best suited for ripping easy tight, swoopy green gravel trails and moderate single track.
In this environment, it’s about as fast as you can make a bike. The flat bar set up helps you lean the bike aggressively into corners as well as having a lot more leverage on steep climbs, with a lot more control in the “tech”.
What’s your build spec?
Frame: Knolly Cache Steel 60cm Pixel Blue
Fork: Knolly Carbon Gravel Fork
Drivetrain: Shimano 12 speed XTR
This is the key part of the build. It’s not so much due to the overall quality of the XTR drivetrain but in particular, two options that are only available in the XTR range:
First is the XTR 10-45T rear cassette (CS-M9100-12, 12-45T). This cassette has closer gear ratios in the four largest cogs than the standard 10-51T MTB cassette and helps to bridge the "roadiness"; of a 2 x road or gravel drivetrain with the simplicity of a 1 x 12 MTB setup. It is fair to say that the entire drivetrain and wheel spec was built around this cassette from the start.
The cassette is paired with the medium cage RD-M9100-GS 12 spd rear derailleur. To match the cassette is an XTR 170mm crankset with a 38T chainring. The 170mm crankarm length was chosen to eliminate pedal strikes due to the very slightly lower BB height from the 27.5 x 2.1” tires (compared to 700c x 40mm tires). The 38T chainring is the largest 12 spd HG+ chainring that I'm aware of (XT comes as large as 36T) and was designed to replicate the 40T and 42T chainrings available on the Shimano GRX cranksets but matched to the smaller 10T cog available on the MicroSpline freehub bodies of 12 spd MTB drivetrains.
Overall, I would say that the gearing range for a gravel bike that's pretty much dedicated to off road riding is about perfect. You can spin out the 38T chainring / 10T cog combination on the road, but only in ideal road riding settings. The flat bar position on this bike is already less than ideal aerodynamically and combined with the slower rolling nature of the 2.1" wide tires on the road (compared to say a 700c x 40mm tire like the Maxxis Rambler), there is little need for harder gearing on the bike.
However, on trails, the gearing is just right. You have an easy enough gear for the steepest climbs (you'll be close to looping out the bike on anything steeper) and a wide enough range for almost any other trail situation including higher speed fire road descents. The gearing is still close enough that you can find a nice cadence in most situations. I spent more time figuring out the gearing on this bike than anything else on the build and in the end, I’m extremely happy with how it worked out.
Bar & Stem
Bar: Raceface Next 35 (760mm width)
Stem: Raceface Turbine 35 x 80mm length.
Who says 80mm stems aren't in fashion anymore?! When converting a drop bar gravel bike to flat bar, the single biggest fitment concern is the reduction in effective reach/effective top tube length of the cockpit. This is because drop bars also have reach built into them, typically in the range of 70-80mm. Flatbars have the opposite, a reduction in reach because of their rearward sweep. But they are also a lot wider and help to spread your arms out, which helps to brings your chest more forward.
Now, moving from a 44 or 46cm wide drop bar with 75mm of reach to a 760mm wide rearward swept flat bar will spread your arms a bit and help offset the loss of reach between bar types, but it won't be 100% equal because you’ll end up with a shorter overall effective cockpit on the bike. So, you need an XC length stem and in my case, an 80mm Turbine stem. Even then, the cockpit was a bit short compared to very modern MTBs. I found a comfortable, progressive position on the bike by making a couple of very small tweaks that added up to give me the room that I wanted for a flat bar build.
The dropper post has a slight rearward bias which positioned the saddle back a few mm. I rolled the handlebar forwards as much as I could tolerate which increased the cockpit length by a few mm.
These two changes were enough to give me the cockpit length that I needed for the flatbar Cache build to feel like a modern MTB fit wise without having to upsize a frame. If you are between sizes, you might want to go to the larger size. We make the Cache in 7 sizes, so the steps between sizes are small and there is a ton of standover height on this bike. I also really wanted to keep the nimbleness that this bike needed to be super fun and didn’t want this bike to be a sled. It’s super responsive when climbing, nimble when cornering and still reasonable on the
Grips: Chromag Clutch
This is a personal choice and my current favourite grip on the market is the Chromag Clutch.
Brakes: Magura MT8 SL Flatmount
Up until very recently, merging MTB and road brakesets has been a bit of a “pick from Column A (MTB lever) and combine with Column B (Road caliper)” and hope for the best. Typically, these setups worked fairly well and would be a SRAM or Shimano MTB lever with a road caliper. With the move to flatmount for XC bikes, Shimano has now released dedicated flat mount brake setups for MTB drivetrains.
However, Magura was first to this game with the their MT8 SL FM (FlatMount) brakeset. I have used the amazing MT7 DH brake in the past and performance-wise it’s absolutely one of my favourite brakesets. The chance to mix things up on this build with an MT8 SL brake with a dedicated flatmount caliper was just too good. It’s also an incredibly light weight option and while absolute lightest weight was never high on the priority list for this bike, I would certainly take a weight savings if it presented itself as well as providing a solution to a tricky requirement.
The result was everything I was looking for, as the ergonomics of these brakes are fantastic and they played nicely with the Shimano clamp. The lever feel is solid and consistent and Magura’s well known market leading modulation is there along with enough stopping power for this build. I went with dual 160mm SL rotors which have been working flawlessly and generate enough power to slow me down, as I’ll break tire/ground traction long before I run out of braking power
with this setup.
Seatpost: Fox Performance Series Elite MY21, 31.6mm x 125mm drop
The new MY21 lever is excellent and this post is one of the smoothest on the market. I went with the cheaper Performance Series Elite post simply because I think it colour matched the bike better. The 125mm of drop is perfect for a few reasons. I will have a saddle bag installed on the post and that uses about 25mm of the drop. So, my “useable drop” is about 100mm with the saddle bag on. Also, since I’ll be commuting on this bike, it needs to have lights which means that I need to have enough “regular seatpost” sticking out of the frame to mount a rear light. Overall, I’m happy with how this turned out and there is enough drop for riding and enough post for a light. I know that sounds “not very hardcore” but it’s highly functional and a versatile solution that’s working great.
Wheels: Industry Nine Trail 270 24H 27.5”
As I mentioned before, there was a lot of thought into what the drivetrain on this bike should be. I was pretty set on having a 27.5” road wheel on the bike and that would mean an HG cassette for a road cassette with an 11T smallest cog. Industry Nine uses an updated Torch Hubset for their road wheels since it has very slightly lower friction than the Hydra hubset. This is pretty sick since they now have two high end hubsets that can be tailored to individual needs based on maximum reduction in friction (Torch hubsets for road) or prioritizing engagement for MTB (Hydra). In reality, both hubs are very close to each other performance wise and we are talking about splitting hairs here. But it’s cool nonetheless. As the build developed and I made the decision to move to a 12spd MTB drivetrain, I realized that I would be looking at an MTB wheelset that had the required Shimano Microspline driver.
When I did the BC Bike Race in 2018, I used a 29” Trail 270 wheelset and it was flawless during the entire event. So, when I9 chief Jacob suggested that I look at a Hydra based wheelset instead of a torch based wheelset for this build, naturally, the Trail 270 came to the top of the list. Given that the wheels were 27.5” and that the bike was going to be used mostly on moderate off-road, I elected to go for the 24-hole version of these wheels and there have been zero issues so far.
They are light, stiff, track amazing well and super responsive under pedalling load. The hub’s engagement quickness is awesome when you just want to stomp on the pedals to get maximum acceleration. Everything on this bike is designed to be precise, quick and nimble and these wheels are a key part of this build and their responsiveness contributes massively to the overall feel of the bike. I also went a bit crazy with the colours on this bike. The goal was for it to be FUN! You can let me know if I succeeded or not in the comments :)
Tires: Maxxis Pace 27.5 x 2.1"; front and rear, tubeless
These were chosen explicitly for this build, being about the smallest "MTB" tires available and also the ones with the least aggressive (hopefully fastest rolling) tread pattern. Overall, they have been a really good choice for this bike. I'm about 97kg (215 pounds) and run them at 50psi front / 55 psi rear for any riding where I'm going to be on the road and about 5 psi less if I'm 100% off-road, which is crazy high, but without suspension for some absorption, this pressure helps prevent flats. Overall, they are decent enough on the road and quick on the gravel. There is enough tread for climbing loose over hardpack and the consistent round profile is great at being predictable in the corners when leaned over aggressively.
So, Flatbar Cache: What is the best use and how is it not just an extra blingy commuter hybrid?
I think this is about as MTB-ee as I’d want to make a Cache (Caches converted for endurance road or Fondos are on the other end). You can of course mount a short travel suspension fork on the front (MRP Baxter, Fox 32 AX40) and some Cache locations will absolutely demand this (rocky desert terrain) if the bikes are being ridden aggressively. But to me, the beauty of riding a fully rigid bike is the precision required to ride it. It’s fast, efficient and can be rallied hard on trails where even XC mountain bikes would be overkill. It’s the opposite of the lower, longer, slacker movement even though the Cache is absolutely LONG as far as gravel bikes go. It’s about feeling every part of the trail, finding each minute section of available traction and maximizing it. It’s about instant changes in acceleration or G forces, rather than big numb “hold on for dear life” moves. It’s about leveraging the shit out of your handlebar on steep loose climb. It’s about cranking on your local walking path or easy trail network for an hour or so to maximize your fun and fitness.
Does flatbar make sense for everyone?
Not if you’re going to be on the pavement or wide open gravel roads for longer rides. You would miss the speed of 700C wheels and the aerodynamics of a drop bar. You’ll miss the gear ratios of a good 2x drive train and your hands will eventually start to complain from the lack of available bar positions to place them. But for the niche (or someone who perhaps does want the blingy hybrid, it can be a hellova lot of fun. Long live 80mm stems!