BB pivot, flexstay, mullet, single speed

[nicrains]

Build log of my 7th frame build.

So it’s a BB pivot, flexstay, mullet, single speed . Kinda built to be a trail/DJ. 118mm rear 140mm front.

3D printed chainstay yoke, SS to link connections and upper shock mount.

My biggest takeaways from this build:
-Brazing doubler plates and stainless is difficult. Pre- drilling holes throughout makes it easier.

-The suspension flexes the stays 5 degrees, so at ride height the stay is flexed 2.5 degrees and halfway through the travel it’s straight and bottom out it’s 2.5. Pre flexing the stays before welding is a must.

-Brazing the HT/DT reinforcements. Probably not worth having, but they look so darn cool. In the future i’d do little stitches of braze. Brazing the whole thing definitely warped the frame a bit.

-I’d make the SS connection dual shear

-The single speed dropouts I wouldn’t do again. It works, but changes the position of the rear disc relative to the caliper.

The frame has made it through a season of riding without braking, so I’m calling it a win!

A version 2 is in the works. Hopefully it’ll be ready for next spring.

I appreciate how willing everyone is to share information here. I’ve learned so much from this forum and couldn’t have finished this frame without it

[nicrains]

[Pax]

Very cool build! I love the look. What size bearings did you put around the BB? Seems like they’d have to be big.

[nicrains]

They definitely are, 40mm id. The bearings are 61808-2rs.

[Fuzzmuffin]

So awesome.

How was the BB main pivot? Did it feel bobby under pedalling even with only 110mm travel?

You sticking to the BB pivot for V2?

I know that is doesn’t matter… do you know the weight of the finished bike?

[vivawanda]

What was the main pivot of BB like? Even with only 110mm of travel, did it feel bobby when pedaled?

[nicrains]

I have the shock pressures farly high, so it’s not super compliant, but there is hardly any pedal bob.

If ya want it to be more compliant and good for chunky trails it bobs noticeably, but still not very bad. Also that’s with only adjusting pressures and clickers on the shock, could probably get a bit better still with working on the valving

I would say right around 30lbs, if not a little under. But that’s with it setup as a single speed.

Definitely sticking with BB pivot for V2, but ditching the flexstay for a rear axle pivot like Treks ABP. Unfortunately on the V2 the rear triangle will be aluminum.