# Frame #7 My cyclocross bike



## adarn (Aug 11, 2009)

Hey everybody. I heard someone say they want more build reports. I was going to wait until this was all of the way done, but what the heck.

After building two bikes for myself and then four more for my friends, I was ready to build one for myself again. I've been wanting a cross bike for a while. 
Mostly for longer gravel road rides and winter road riding up here in snowy Montana. So this is what I came up with.

This build was the first that I drew a full size drawing for, and it was extremely helpful. I think I'll be doing that for a while until I feel comfortable without it.









Another new thing I did on this frame was to start off mitering the rear end. I liked this, because I usually breeze through the front 
triangle and then get super antsy on the rear, which of course is much harder. This way, I think I ended up with a better rear, and it helped keep the 
momentum going once I finished the front.



























After that, another new thing I did was to completely dry fit everything. Before I was doing BB to ST, then miter the TT, TT to ST (full braze), 
TT to HT, then miter the DT to what I had. I guess I thought that this could "absorb" any mess ups I Had, but always ended up 
with the DT being a ***** to miter. 
Anyhow, this time, I mitered all of my tubes and checked them against the drawing and that was a good way to make sure that I was building what I designed.



















Yeah so then I taked the whole front triangle up at once:









At this point I got to do something new as well, which was to check it on a surface plate. It turns out that one of my professors at school used to build bikes professionally,
and was actually building MTB's back in the late 70's and 80's. He was happy to help me out with all this stuff, and gave me some great advice, 
which was super cool, being pretty much entirely self taught. 
Anyhow, It was pretty off after I tacked it, but we figured out how to fix it, and I got everything within a couple of thousands of an inch!
I'm super excited about that.

Then I just rolled right into the rear triangle, which also turned out well. This bike is the first geared bike that I have built, so there were a lot of brazeons, which took forever.

Well, this post is getting really long, I'm sorry. I'll just post pictures of the final product here, let me know if you have any questions. 
The bike is at the powder coater's right now and should be getting built up in a couple of weekends when I'm supposed to have it back. More pics then.





































Thanks for lookin!
Adam


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## RCP FAB (Jun 15, 2011)

Love the rotor bridge. Good work!


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## adarn (Aug 11, 2009)

RCP FAB said:


> Love the rotor bridge. Good work!


Thanks!! Turns rotors look pretty cool, are 1,000,000 times easier to miter than a tube, and I have a pile of trashed ones in my garage that are perfect for it.


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## Walt (Jan 23, 2004)

Sweet!

-W


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## shirk (Mar 24, 2004)

Thanks for posting.

Pretty sure you referenced my comment about wanting to see more builds.

My first box of tubes should arrive in the mail any day now and I almost have all the components for my torch set up. Super excited.


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## mickuk (Jul 6, 2007)

Nice build - thanks for showing!

It sounds like almost everyone hates rear stays.I'm just building a bit of an oddball frame - front end is done, but need to do the seatstays and dropouts next, then finally the chainstays (don't ask why but there are reasons for this). Will be interesting to see how that goes......


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## MDEnvEngr (Mar 11, 2004)

Very nice! A cyclocross bike with bottle bosses?! Sacriledge! Or at least it would be considered so in other places. I like the seat tube sleeve. I'm self taught too, and love to see others dealing with figuring it out by themselves. B


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## G-reg (Jan 12, 2004)

Good work, care to elaborate on the seat tube sleeve? What tubes are you using for the sleve / seat tube?


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## TrailMaker (Sep 16, 2007)

Looks Great!

I actually like doing the rear stays. Lots of opportunity for craftsmanship back there!

Post up soon, and keep your bolts tight!


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## Eric Malcolm (Dec 18, 2011)

*Congratulations, really good effort here.*

Like the Sleeve and the 'S' cutout, old crafting that is.

I would encourage doing the D/T mitering first before you do the T/T. I found it much easier as the TT mitres are close to Square, but the D/T has a steeper angle to file at the H/T.

Glad you discovered the full sized drawing, I still do this after several years. I simply like to see it in real size before I build. I can put components on it and do checking of tube lengths as you have discovered in mitering. I also put along the tubes drawn where the Butts are. I find this very useful knowing where thicker tube is and where its thin. You can't see these from the outside of the tube and it helps if you venture out of the norm as I do from time to time to be sure I have sufficient wall thickness before cut and burn. This also alerts me to where strengthening is needed eg: sleeving, to ensure a strong build. This also helps in ordering individual tubes as opposed to Tubesets and expands your structural engineering knowledge.

Keep up the good work.

Eric


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## adarn (Aug 11, 2009)

MDEnvEngr said:


> Very nice! A cyclocross bike with bottle bosses?! Sacriledge! Or at least it would be considered so in other places. I like the seat tube sleeve. I'm self taught too, and love to see others dealing with figuring it out by themselves. B


Thanks! and is it??? I'm not that into the cross scene, but I'll definitely want to carry around some bottles. I'm planning on mostly using this thing for really, really long gravel rides. I'll probably race collegiate cross on it in the fall though. I guess I could take the cages off if I wanna look cool then.



G-reg said:


> Good work, care to elaborate on the seat tube sleeve? What tubes are you using for the sleve / seat tube?


Thanks!! The tubes are true temper, mostly Verus. It was my first time working with them, and I'll definitely be switching over. They were a really nice and I like that they were made in the USA.
The Sleeve is just straight gage 4130 from aircraft spruce. I know the OD is 31.8, I want to say its .035, but I'm not sure on that.

Also, thanks Trail Maker, and Eric!


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## adarn (Aug 11, 2009)

Hey everyone,

Just a quick pic for now. The powdercoater said it would take 2 weeks, but it ended up taking 2 days. I'm pretty happy. The color came out just like I wanted. This thing looks legit! 
I'm waiting on a chain in the mail, but I might just have to go buy one. Can't wait to ride it.
More later.








-Adam


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## Walt (Jan 23, 2004)

Needs a Sklar fork on there, I'd say...

-W


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## adarn (Aug 11, 2009)

Walt said:


> Needs a Sklar fork on there, I'd say...
> 
> -W


I think you're probably right...
I've got a fork jig to borrow, now I just need to figure out what I'm gonna make and how I'm going to afford it haha.

Thanks for the encouragement Walt! Couldn't have gotten this far without your help!


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## J_K (Jan 18, 2010)

Very nice, I like straight stays. How much tire clearance you have there and what chainstays you used?


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## adarn (Aug 11, 2009)

J_K said:


> Very nice, I like straight stays. How much tire clearance you have there and what chainstays you used?


Thanks! I've got enough for 42's. I'd like more but oh well. They're True Temper stays, not sure exactly which ones. Next time i would use single bends, or maybe have an excuse to buy and arbor press and bend 'em a tad.


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## adarn (Aug 11, 2009)

Alright, here are some better pics and stuff!

I'm sure that this bike is best looking one that I have built, the finnish came out really nice and the I think the powdercoat looks great. It's hard to tell in the pics, but it's sparkly purple too. I dig it.

Anyway, It was like 50 degrees in Bozeman today, so just about as perfect as it gets for a January bike ride. The bike rides how I wanted it too, which is cool! I'm not a big fan of being super hunched over or drops, so I built it short, and that seems to have done the trick.

I also think I did a really good job of tube selection for this bike. It seems to be stiff in all the right places. I had virtually no noticeable flex in the chain stays or rear triangle, which is awesome, but still that good steeley feeling. "Laterally stiff, yet vertically compliant" you might say.

Anyhow, I'm very pleased with the end result. I can't wait to take it on some dirt!
Oh, and those gears... they're not too bad either (this is my first geared bike in 4 years)

Yeah, so I learned a lot on this frame and came out with a sweet product. Couldn't be happier.

-Adam


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## Meriwether (Jul 26, 2007)

Awesome purple color!! I like!
That's a great all-rounder cross bike with the discs, congrats and enjoy!


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## TrailMaker (Sep 16, 2007)

Nice ride!

Hitting the targets is always very satisfying. Enjoy!


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## febikes (Jan 28, 2011)

Looks like a great area for a bike like that.


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## davesauvageau (Jan 8, 2010)

Great looking bike and that purple is ridiculously awesome! The pulley seemed to be unreliable and kinda sketchy for me so I went with a Shimano CX-70 Top Pull front derailleur on my CX bike.


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## adarn (Aug 11, 2009)

Thanks guys! I'm really stoked on how well this one came out.

Mark, Hopefully this bike is, I designed it thinking of the endless gravel roads that Bozeman has, whith fun little trails mixed in. Should be great once the snow melts!

and Dave and Whit, thanks, I'm a big purple fan.


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## Eric Malcolm (Dec 18, 2011)

*Nice Bike*

Adarn

I am in the same position as you are regarding a groupset, and having a bottom-pull front derailleur.
My options were to use a pulley as you have done, purchase a Shimano CX70 braze-on top-pull, or alter the derailleur that I have.








I'm not sure if you are into making or altering components, but I share my own versions to inspire anyone interested.
The swing-arm took about 4hrs from thinking about it to completion.

Eric


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## adarn (Aug 11, 2009)

Hey Eric,

I looked into the swing arm option. Is it up and running yet?
I thought about trying it out, but figured that messing with a frame is easier than a component.
The pulley is working great so far, but we'll see how it holds up.

-Adam


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## Eric Malcolm (Dec 18, 2011)

No, its not working at this stage. I have a project bike getting underway, and it requires alot of modifications of components, and this is a tick off the list.

I tried to get a exploded picture on the thread, but it appears I cannot due to too much memory.

It is very easy to make, just file the riveted pin end off the cage and it all comes apart. I used a SS bolt to replace the rivet.

Eric


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## adarn (Aug 11, 2009)

Cool, I'd love to see pics if you can figure out the posting thing!


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## Eric Malcolm (Dec 18, 2011)

*Adarn, better late than never.*









As shown, it is pretty much a mirror image of the original.

Eric


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## dr.welby (Jan 6, 2004)

Eric Malcolm said:


> As shown, it is pretty much a mirror image of the original.


Does that actually work? Seems like the attachment point can only move a few mm upwards. As my brain is processing it, you don't want a mirror image, you want to flip the input arm 180 degrees, which puts it just above and outside the lower pivot for the cage.


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## Eric Malcolm (Dec 18, 2011)

Yes, I know what you are pointing out. You can do it that way (180 degrees) as long as the movement allows clearance with the crankarm. With this one, I intend to cable it from a low position on the seat tube. This modification does require a bit of thinking through in this respect. You need to to draw it out and measure, measure, and measure again. A problem teaser for sure.

Eric


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