Drop Bar MTB Geo

I’d be interested, given your experience and perspective - what would you consider to be solid geometry for the drop bar MTB - head angle range and STA range specifically!

Hey Upcountry, it’s been a while with your Epic rig, how has it been for you? Any new changes?

More specifically, how do you feel about the trail figure of your bike? My calculations have me at about 76-80mm… depending on tire size.

With usual gravel trail figures in the 60’s, i’m not sure what kind of handling characteristics to expect. Maybe someone could enlighten me, or share their experiences.

Let me preface what I would consider a solid geometry (for me) with the recommendation that you should choose the geometry (or base MTB frame/bike) according to what you like and what you want to ride with it.

If you like to have fun shredding gnarly downhill trails, doing berms, jumping off tables or find yourself in rock gardens most of the time chances are you prefer a pretty slack bike. Not to say you probably own already a downcountry bike or even a trail bike for exactly this. But then I would also ask: why would you want to consider a dropbar bike, even if it’s a dropbar mountain bike for this kind of riding, at all?

So chances are you want a capable rig to go nearly 100 % off-road and be comfortable and fast at the same time. But you wanna actually ride that thing. As in like: pedal it. Over plains, over easy to more steep climbs and over never ending tailwind driven descends (oh what fun!) and of course also the not so occasional steeper stuff - but within reason. So - you want a good pedalling and a nicely steering bike. Nicely steering on the flat and in slow to medium fast corners. Or very fast corners, but then on fire roads or maybe even tarmac. An allrounder. Not a downhill oriented bike.

This brings you into steering angles of around 70 degrees, give or take and in consideration of all the other parameters. Take into consideration that with suspension you have to look at dynamic or sag-corrected fit. E.g. my Canyon Exceed has a steering angle of 69°. Lower than 70, right? Well, no. With a 100 mm travel fork, set at 25 % sag I’m sitting on around 70.1 degrees. Use this as a handy calculator (Sagged Hardtail Geometry Calculator - MAD SCIENTIST MTB - Bike Geometry Calculators)

When under braking or cornering forces I’ll become even steeper.

I recently tested the new Trek Supercaliber. It has a 67.5 degree steering angle. On paper and when looked at the wheel flop parameter (Compare: 2022 Canyon Bicycles Exceed CF S vs 2023 Trek Bikes Supercaliber SLR 9.8 XT S - Bike Insights) it depends whether you consider this a significant difference or not. But let me tell you: It felt like night and day and the Supercaliber has a very and instantly noticable wheel flop where my Exceed is perfectly neutral (w/o not being unstable or insecure feeling). I didn’t like the new Trek at all. Also not from it’s rear suspension but that’s not the topic here.

So in Summary: I do recommend not going slacker than 69° head angle (can be a bit remedied for newer, slacker bikes specced with a 120 mm fork by using a 100 mm fork with those) and above all: ride the original bike as it comes with the flat bar. If you dig the riding on it you know you’ve found your bike and you can just put drop bars on it (provided there’s nothing super proprietary going on with it which would make it mechanically difficult to put a different stem on it).

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Yea, aero frame. I have a BMC Kaius on 35’s and that thing is fast :dash::dash::dash:

If you’re planning to go narrow on the bars, installing an angleset “backwards” to make the head tube angle steeper is a great way to control the wheel flop without making your seat tube angle even steeper.

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I thought it was that bar ends liked to snag on things. Thats why i dropped them at least.

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Here’s mine. It’s a ton of fun. Scott Scale 925

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Frame: SpCycle M-038 (size S , 778g)
Fork: FK-016 (455mm , 502g)
Groupset: Sensah 1x12
Weight: 8.4kg

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Very nice, you made that fork look very good!

What size of frame do you typically ride? What is your height? Would love to hear about your experience with the fit/stem length.

Thanks!

My height is 170cm, I usually ride a size S bike. This bike has an 80mm/-7degree stem and zero offset seatpost.
Handelbar specs: 380mm/65(!)mm reach/80mm drop (https://a.aliexpress.com/_EIJW9U5)

I feel comfortable, but I want to replace the 80mm stem with 70mm to move the saddle back (now it is pushed forward as much as possible)

I’m also thinking about replacing the fork with this one: (https://a.aliexpress.com/_EJzmLBT)
for a lower landing without loss of tire clearance

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