Weight Weenies

I'm in to process of building up a SuperSix Di2 frame and I'm wondering how much I should be worried about the internal wires being rubbed by the BB30 spindle. With the Shimano bottom brackets there is always a plastic sleeve, but I don't see how I can keep at lease one wire from rubbing the axle unless I hold it to the bottom of the frame with vinyl tape.

Am I just over thinking things?

You could use a small length of heat shrink or a drinking straw. It's not necessary though, there's no force pushing the wire against the spindle. It might wear through in 10,000 miles or so. Maybe. But you're probably switching parts and rewiring a little more often than that, right?

Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com

I've got over a thousand miles on my SystemSix with a section of yoghurt pot used to hold the Di2 wire away from the rotating axle.

The wire runs in the hole that was previously used to locate the BB wire guide, is held against the inside of the shell by the section of pot, and then runs up the seat tube to the in-seat-post battery.

DaleRider wrote:I'm in to process of building up a SuperSix Di2 frame and I'm wondering how much I should be worried about the internal wires being rubbed by the BB30 spindle.

Agree that it's probably not a huge deal. Are you planning to use a Shimano crank? I recently built a supersix with a Sram PF30 bottom bracket, Sram crank and Di2 transmission. The SRAM BB had a sleeve:



If you're going Shimano crank, consider the Praxis PF30/BB30->Shimano Hollotech adapter. It comes with a sleeve and the adapter design is quite smart:

http://praxiscycles.com/pages/conversion

@415brian I have the Praxis BB in my cross bike and I love it.

I'm going to be running an SiSl2 crank with Spidering gears for this build. I'm trying to save weight where possible. I've posted details in the build thread I've got in the Intro/Gallery section.

DaleRider wrote:I'm going to be running an SiSl2 crank with Spidering gears for this build. I'm trying to save weight where possible.

Gotcha - sounds like you already have a (sleeveless) SiSl2 Cannondale PressFit Bottom Bracket. If you wanted to, could you run a (sleeved) Sram PF30 bottom bracket with the SiSl2 spindle and spacer bits? Now I'm just curious.

Of course, that's probably not worth the money. I'd probably just hide or tape the Di2 wires as best you can.

Your build is similar to mine and that's probably why I think it looks sharp.

I think I'm going to go with a bit of this instead.



Doesn't weigh much and should provide more than enough protection.

DaleRider wrote:I think I'm going to go with a bit of this instead.

good call!

I've done a few bikes like this and have taken PF30 bb's, removed the bearings and cut the cups down so that they fit inside the frame but left them large enough to have friction between the shoulder and the frame. That way they stay centered and have enough friction that they don't spin.

I just built up my Parlee Z1 with a PF30 bb with the Cannondale SISL2 Spiderring crankset and the Shimano DA 9079 DI2 drivetrain.

My builder used the Cannondale SL2 68x109 mm Ceramic bb part no. KP247 plus the PF30 shell from the Cannondale Pressfit BB30 PF30 bb shell part no. KP197 because we were concern qthat the DI2 wires might rub against the rotating axle if we used the Cannondale SL2 68x109 mm Pressfit Ceramic bb part no. KP248 that has a bearing PF shell/shield only. You can look up these parts at the www.cannondaleexperts.com site.

Or, you could use the SRAM Pressfit Ceramic BB30 Part no. 12XS267. That was what we used for my Lynskey Helix OS with a PF30 bb with the Cannondale Hollowgram SISL crankset with the SRAM Red drivetrain.

Mark

i have a similar concern. i intend to use square taper BB. Those that should have enough clearance to run the wire in between the BB and the shell are -

1) http://www.whiteind.com/bottom-brackets.html
2) http://www.specialites-ta.com/gb/boitier-axix-rte.html

Can anyone suggest others that can be used?

Here's another option...a simple rolled up piece of plastic. In this build, I'm using a Praxis BB30 adapter for Shimano Hollowtech cranks.

Photos below. The non-drive-side of the Praxis converter is installed, but not the drive side yet. First picture is the Di2 wires, second is the plastic shield, and the third is the shield installed. It's working surprisingly well. It's light, the wires are protected, and there's zero friction:

That's clever, thanks 415brian.

Did you end up drilling holes in the bottom bracket shell for the Di2 wires?

Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com