2011 Fixie Inc Pure Blood Cyclocross Bike Goes Disco Only

For 2011, Fixie Inc has gone disc-brake-only with their Pure Blood cyclocross bike, and made a few changes to drop weight in the frame and fork over the 2010 model.

Visually, the biggest change (other than the bright yellow color) is the movement of the rear caliper to the inside of the triangle, mounting it on the chainstay rather than the seatstay. Cable routing now runs under the downtube with full length housing to the brakes, which runs through the fork and chainstay tubes.

Component spec is SRAM Force’s black groupset and blacked out parts throughout. Frame material is custom drawn 4130 steel and a steel DiscO fork.

More pics behind the jump…

Pics via BikeMagic.

Comments

uglyyeti - 09/03/10 - 7:59am

Can’t figure out the logic of bridging the seatstay and chainstay with the brake caliper. Seems like that introduces multiple potential undesirables there – flex, rub, fatigue?

Mark Adam - 09/03/10 - 8:40am

I disagree. I think it produces an extremely stable and secure mounting and henceforth braking point for the caliper. A lot of mountain bike designs, especially 29er where the wheel is larger requiring a greater stopping force, are moving toward this bridged mount design.

dave - 09/03/10 - 11:34am

>> A lot of mountain bike designs, especially 29er where the wheel is larger requiring a greater stopping force, are moving toward this bridged mount design. <<

I really hope you are kidding. If not, then there are clearly a lot of 29er frame designers with a poor understanding of engineering.

Keeping lever pull strength and rotor size equal, 29er braking torque is LESS than 26. You have to pull the lever harder or increase rotor size to get the same deceleration from a given lever pull strength on a 29er, this does NOT mean the torque exerted on the frame is greater.

Sheesh, only in the bike industry would anyone make an absurd claim like this.

Isolation Helmet - 09/03/10 - 1:14pm

It’s all about triangulation. Strongest structure in construction. Placing the rear brake where it is forms a very sturdy triangle.

Snakeboat - 09/03/10 - 1:52pm

why the heck are there gears and freewheeling on a Fixie Inc bike?

uglyyeti - 09/03/10 - 2:30pm

The triangulation theory (awkwardly mounted on an elbow) holds weight only if we’re assuming the brake caliper body is pulling double duty as a brake and a structural frame member. I’d like to see SRAM’s warranty folks weigh in on that one. They’re using the caliper as a gusset, not attaching it to a gusset.

Those CPS bolts that are now under torsional loads also maintain the alignment of the caliper, right? Rub a bit in the corners, does it?

dave - 09/03/10 - 7:36pm

>> Those CPS bolts that are now under torsional loads also maintain the alignment of the caliper, right? <<

The whole point of going from iso to post mount was to eliminate shear loads on the bolts. This defeats the purpose.

The torque generated by any rear brake is pretty tiny anyway since the tire will skid before the rear triangle deflects.

dementor - 09/14/10 - 3:23pm

>> You have to pull the lever harder or increase rotor size to get the same deceleration from a given lever pull strength on a 29er, this does NOT mean the torque exerted on the frame is greater. <<

Yes it does. Compared to a 26er, you have to pull the lever harder which increases torque exerted on the frame. However, the difference is only about 10% and especially in the rear is a non-issue. I run a 140 in my 29er MTB and can lock the wheel with one finger in any situation.

J. P. - 09/18/10 - 10:29am

The old model is much nicer looking.

SH - 10/21/10 - 3:56pm

If you’ve seen the show with the hydraulic converter from Trickstuff!, you’d know why this frame rocks. It’s post mount so eventually you can run hydros w/o caliper adapters. The fork is hot…all steel. The way it’s mounted doesn’t add more force into the caliper because it isn’t mounted in tension or compression. The caliper/lever rotor generates force when you’re BRAKING. The frame doesn’t create force upon the caliper ever, duh! The caliper is mounted so low and simply that there will no relevant detrimental effects to braking. By the way…how do YOU increase force at the lever WITHOUT increase torque exerted at the rotor? I think you mean(just like higher gear ratios) you’ve got less mechanical advantage on the rear wheel, but this actually INCREASES torque required for braking/stopping. For rim brakes the opposite is true.

SH - 10/21/10 - 4:06pm

re:dave Do you know shear load is? I really doubt it. On IS mounts to force is acting perpendicular to the bolts THAT is shear. Take more than 2 seconds to evaluate how PM distributes braking force and you’ll see the force is either compression(moving forward while braking) or tension(moving backwards while braking: trials). The bolts are strongest in this plane and these force vectors. The caliper and both bolts are forward of the axle not centered. Braking force with discs is applied rotationally ONLY. It does apply more force to the SPOKES on the NDS, but nothing that tangentially laced wheels are not constructed to handle.

fork searcher - 11/30/10 - 3:26pm

Does anyone know the fork length (hub to head tube) of the pure blood 2011?
Why ever Fixi Inc. did not answer that question to me.

thanks!

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