The stupid CX build. Disc. FlyXII (china) carbon frame. "Dura ace" Di2. 1x11. Mud.

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dmcgoy
Posts: 43
Joined: Thu Nov 15, 2007 7:23 pm

by dmcgoy

I have two road bikes. One is a cheap-o fixie that I use to pull the kid's trailer and do town runs. The other's I use as a 25 mile round trip workhorse through a hilly and stop-filled commute. In the fall, it doubles as a CX racer.

The spine of this build is a few years old. The FlyXII FR-602 (superseded by the FR-603, which I believe is identical but has a redesigned fork less prone to cracking). Very cheap now. Wasn't too much when I bought it either - around $550 USD shipped?

I was using this frame with a SRAM 10 speed drivetrain and TRP spyre brakes. Since the main use of the bike to commute I stop a lot. Also, my route is hilly. Plus it rains. So disc. But I was not super happy with the brake system. Lever feel only felt fine within a few months of running new housing and cables. I felt like I had to tweak the brake pad adjust every week. The sensible thing to do would be to try the TRP HY/RD or the Juin Tech X1, but I'm not sensible. Plus I was getting really upset I could NOT get the front derailleur to reliably shift the front ring. It felt like I could only get it set up to almost shift or drop the chain.

I wanted two things: hydraulic disc and reliable shifting. There also was the complication that my wheelset wasn't 11 speed compatible. I ended up with a 9170 Di2 shifter - XT M8050 rear derailleur - RS785 caliper - 1x11 system. I went Shimano since I read that their hydraulic brakes performed better than SRAM and went Di2 partially because the it is the only way to get non-humongous shifters. I wanted the 8070 shifters, but they still aren't available. Since I didn't want the new build the miss this CX season I did the stupid thing and bought the 9170 shifters.

The goal was to get the bike under 8 kilos and I surprised that I actually did it. Surprised because the bike was lighter than the build sheet said it should be. With a fancier carbon frameset and a $1000+ wheelset this build could approach 7.5 kilos for a CX race.

Future tweaks include SRAM Red hollowgram crank arms, Wolf Tooth chainring, and carbon spacers for the steering tube. Plus a bath.

Build Sheet
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The bike. After a muddy CX race. Still needs a proper cleaning.
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Beautiful 9170 levers.
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The awesome new Shimano 11-34 cassette that fits on a 10 speed hub.
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Bike stand
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Sram Force crank arms with Look Quartz pedals (still works fine even in heavy mud)
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China saddle and Ritchey WCS seatpost. Could save another 50 grams with a fancier non set-back seatpost
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MT800 'Junction A'
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RS785 calipers (post mount frame) and A2Z two piece 160mm rotors
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Johnny Rad
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Joined: Fri Feb 17, 2006 6:22 am
Location: Zion

by Johnny Rad

Great photography work, but I can't get over all the mud! It makes my skin crawl. :D

I treat my bikes like they're made of sugar and will most likely dissolve in the rain...

<><><>

Did I miss the size of your front ring? What have you paired with your 11x34 cass?

by Weenie


Haydn
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Joined: Fri Sep 04, 2015 10:08 am
Location: UK

by Haydn

Good stuff :beerchug:

dmcgoy
Posts: 43
Joined: Thu Nov 15, 2007 7:23 pm

by dmcgoy

Johnny Rad wrote:Great photography work, but I can't get over all the mud! It makes my skin crawl. :D

I treat my bikes like they're made of sugar and will most likely dissolve in the rain...

<><><>

Did I miss the size of your front ring? What have you paired with your 11x34 cass?


I'm a bit horrified too. Plus I think the course had poison ivy on it since my legs...anyways, I need to be very careful cleaning it off.

The ring is currently a 42t. Which is a little too small for commuting and a little too big for CX. So I have 40t and 44t chainrings that just arrived.

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LouisN
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Joined: Mon Feb 19, 2007 3:44 am
Location: Canada

by LouisN

Love your post, pics, and bike :beerchug: !!

Louis :)

dmcgoy
Posts: 43
Joined: Thu Nov 15, 2007 7:23 pm

by dmcgoy

Some comments on building Di2 (from the perspective of someone who is upgrading from 10 speed SRAM).

1. Those cables are tiny and expensive.
2. It is nice you just hook them up together and it works (though not as cool sounding as the 'wireless' solutions)
3. Also nice that you can upgrade firmware from your phone and tweak the button functions
4. Not so nice that when I was upgrading the firmware the app crashed and the Di2 shifting didn't work. I only got it working by unplugging the battery. I think what happened is the app crashed and the shifters were stuck in 'communicate with app' mode. Still too terrified to try to update firmware.
5. I jammed Junction B inside the frame and am kind of scared that I won't be able to fish it out x months or years from now.

Performance comments.
1. Seems a touch slower to shift than my old SRAM system. But far less energy expended.
2. Reliable, unless your derailleur hanger screws get loose during a race because you didn't put loc-tite on them. Or the next race was so muddy and grassy that the derailleur wheels almost froze in place because the grease got replaced with dirt and, overall, the friction in the system got so high that the derailleur hanger exploded into two pieces while climbing the last hill on the last 1/3 of the last lap and I had to finish in a jog watching at least a half of dozen people ride past me.
3. The braking is fabulous. Just like my mountain bike. Nice lever feel. During a muddy race it was great knowing that I would be getting a very predictable response when pulling the lever. Power is good, if your rotors have a decent amount of metal on them and stay oil free (which didn't happen because my first R785 caliper weeped oil under use).
4. Bleeding was tricky. I had trouble getting it firm enough. I read a tip somewhere that after you bleed it, loosen the caliper bolt and force a touch more oil in. That helped a lot. But finicky. I actually pushed too much oil in when I did that and couldn't get the pistons to retract enough and had to take a touch of oil out.
4. Cool that you can adjust the rear derailleur 'trim' WHILE riding if you didn't get the calibration right on the stand.

Overall, happy. But I also expect it to perform about the same 6 months from now with minimal upkeep. I'm hoping that will be the case.

IamnotWiggins
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Joined: Wed Aug 07, 2013 10:31 am
Location: Brighton, UK

by IamnotWiggins

No notes on how much the mud weighs? Poor show.

dmcgoy
Posts: 43
Joined: Thu Nov 15, 2007 7:23 pm

by dmcgoy

IamnotWiggins wrote:No notes on how much the mud weighs? Poor show.


Not much point. Was wet mud during the race. Plus huge build up around the crank arms / seat tube area. For the next muddy race I'll try to remember and bring my scale. It felt like the bike gained at least 2 kg.

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deano87
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Joined: Tue Oct 17, 2017 4:18 am
Location: Melbourne, Australia

by deano87

haha this is awesome!
Great photos
The Journey is more important than the Destination!

IamnotWiggins
Posts: 153
Joined: Wed Aug 07, 2013 10:31 am
Location: Brighton, UK

by IamnotWiggins

dmcgoy wrote:
IamnotWiggins wrote:No notes on how much the mud weighs? Poor show.


Not much point. Was wet mud during the race. Plus huge build up around the crank arms / seat tube area. For the next muddy race I'll try to remember and bring my scale. It felt like the bike gained at least 2 kg.


Wet & dry weights will suffice next time :D

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ms6073
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Joined: Fri Jul 23, 2004 8:24 pm
Location: Houston, Texas

by ms6073

Johnny Rad wrote:I can't get over all the mud! It makes my skin crawl. :D

Many CX racers would argue that this is how a cross bike should be photographed. :beerchug:
Last edited by ms6073 on Tue Nov 14, 2017 2:28 am, edited 1 time in total.
Michael - The Anaerobic Threshold is neither...

dereksmalls
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Joined: Tue Aug 02, 2011 9:20 pm
Location: New Zealand

by dereksmalls

ms6073 wrote:
Johnny Rad wrote:I can't get over all the mud! It makes my skin crawl. :D

Many CX racers would argue that this is how cross bike should be photographed. :beerchug:


I couldn't agree more!!

Mtek
Posts: 107
Joined: Tue Jun 13, 2017 4:27 pm

by Mtek

I wonder how many beside me are using that first pic for their comp background now?

Great thread, thank you.

lone wheeler
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by lone wheeler

Best pics I've seen on here in a long time! Well done, love it.

by Weenie


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TonyM
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Joined: Thu Jan 22, 2015 4:11 pm

by TonyM

Not a fun of the mud.....but this set of pics is really good !

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