Meet the Dobro.Velo Planina

Hi there,

I called my little imaginary bike brand “Dobro.Velo” because my family name is “Dobrowohl”, and dobro just means “good” in many slavik languages. Going along with this slavik theme, I try to find names for my bikes from that part of the world. My gravel frame from last year is the “gramoz” (just meaning gravel in Slovenian), and this one is the “Planina” which is “Mountain” in croatian/serbian. It is also inspired by a beautiful mountain range I visited a couple of years ago in southern Serbia called the “Suva Planina”

Originally, I started thinking about this design three years ago, when I was toying around the idea to go full commercial and actually have a real brand. The design is essentially a four-bar with one of the links missing, so the rear triangle has to flex a bit to compensate for that. I believe that this arrangement works particularly well in steel, and lends itself quite well to small-scale production since it is quite simple.


The bearing arrangement is inspired by “Last Bikes” in Dortmund, Germany, a business I am friends with. There is no bearing in the main frame, just pieces of solid bar with quite chunky threads in them (M14x1.5 in my case). Six bearings sit in the rocker arm and two in the swingarm. There is no complete axle going through the whole arrangement left to right, which makes manufacturing and assembly really easy.

The kinematics are nothing out of the ordinary, about 100% antisquat on the largest sprocket, 32% progression in a 1:3 leverage ratio (going from 1:36 to 1:24 if I remember correctly…) I can dig out all the linkage plots if anyone is interested :wink:

The two most challenging things during this build for me were

  1. making a lot of one-off positioning fixtures. It’s kind of hard to hit the sweet spot of how much effort you want to put into a fixture that you’re probably never going to use again!
    And

  2. brazing all those awkward inaccessible different wall thickness acute angle weird spots… I’m definitely not super skilled at the torch, but I can manage a tube joint with some confidence. On this frame though, I struggled a lot with heat mangement, torch control, visibility…

Alright, pictures!















Thanks @Fuzzmuffin for your encouragement and help while brazing the seatstays on, and @TDB for our conversations concerning flex pivots

Tomorrow is the first real ride out, I hope it doesn’t fall apart! :rofl:

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Looove it! Have an awesome first ride!

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Woot! Looks amazing. The aesthetic is great.

Curious how much flex you expect from the rear triangle. Is the “flex point” on the seat stays near the rear dropouts? Are you using dropouts for the upper seat stay-to-rocker attachment?

Can’t wait to hear the ride report!

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Hi Colin, thanks for your kind words!

Yes, the flex point is near the dropouts in the seatstay, I “smooshed” the tubes with some 3d printed dies inspired by your metal ones :wink:

Laterally, the rear triangle is surprisingly stiff. The rocker bracing adds a lot of stiffness to the already quite chunky yoke/main pivot area. I did a lot of back and forth on that design, didn’t want to incorporate a seatstay bridge because that would have meant either a different seat tube position or a longer swingarm, neither of which I was a fan of…

The seatstay-to-rocker-attachment is home made on my lathe, it’s essentially just a cup with a thick bottom plate and a little dome in the middle, with a threaded hole, and then I chopped some of it off. Ignore the angle on the drawing, I just eyeballed that…

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Don’t sell yourself short mate!

What a bike!
It was awesome to just watch the whole thing come together and pick your brain during the process.

I can’t wait to chase it down on the local trails… after a few more weeks of spring skiing :wink:

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I would be very interested to hear how it rides. Do you find the shock compression tune too stiff? Especially the low speed compression, because of the flex stays. It should also lower the coil spring stiffness.

Glad there is a mtb build in this forum. Pumps a little more testosterone in here.

Hi Robert,

right now, the spring stiffness is too soft for my weight, so I can’t really comment on how it rides yet. The force needed to flex the stays is negligible though, without the shock installed I can move the rear axle through the travel with my pinky finger. It only needs to flex +5/-2mm going through the travel at the tip of the seatstay.

I will get a stiffer spring today, hopefully it’s stiff enough so I can start playing around with the damping

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Although this is a bit unrelated to the too-soft-of-a-spring issue, have you thought about a springdex?

I would probably get one for my next coil mtb.

Yes I have but I must admit I do like the looks of the bright yellow “Swedish gold” Öhlins spring :wink: Haven’t decided yet though… I’ll get a 550lbs/in spring today (currently running a 500)

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Great design and build! Looking forward to hear how it rides :slight_smile:

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