Hongfu FM079

[Klaster_1]

I had to connect the charger after power elements were replaced, otherwise it wouldn't shift. Works without the charger afterwards. Now I have to put everything onto the bike.

[takolino]

This changes my thinking on using di2 for 1x setup. Will be lighter than etap. Will you tune the cables? The extra protective shield doubles the weight of the cables. You could also hard wire the battery and shrinkwrap it to save a few more grams. You got rid of the housing anyway so just go all the way. Where will you put the junction?

175mm of cable. Could have cut the shielded wire shorter and sanded down the solder.

[Klaster_1]

Will you tune the cables?

That's an option I've been considering, but I'll have to find suitable, lightweight wire first. Any ideas? And then there's a question of Di2 connectors: do I splice old ones, source spares elsewhere or 3D print my own? I'll need to buy a soldering kit for this too, the batteries were soldered in a local electronics repair shop, I no longer have access to a lot of tools after moving away from parents.

You could also hard wire the battery and shrinkwrap it to save a few more grams. You got rid of the housing anyway so just go all the way.

Not sure I follow you. I plan to put a thin plastic bag over the battery and hang it in seatpost on a string, without the casing.

Where will you put the junction?

FD hanger recess looks suitable. Maybe stuff it into the downtube. Definitely not anywhere around the cockpit. If none of these work out, I can always try other options.

175mm of cable. Could have cut the shielded wire shorter and sanded down the solder.

More like 175cm

[takolino]

With all the skill you've shown us already, I think you'll have no problem soldering. You can get a soldering iron fairly cheap. Go to your LBS and see if they have broken di2 cables. I have sheared one somehow and that's what I used. Don't bother 3D printing, the connectors are precise.

Your battery still has the di2 plug on it. You can remove it and solder cables onto the circuit board. On the other end, solder a di2 connector.

Corrosion is your enemy. You probably should use some kind of sealing product. Like a sealant spray or a dip. After sealing, you could shrinkwrap the battery assembly. Heatshrink all cable connections too.

The junction should be accessible because that's how you'll charge the system. I prefer the bar-end type but that one may be heavier than the junction you already have. You always need a junction to split wires. If you need to put the battery in the seat post, you'll need a junction to split the cable for the derailleur. For minimum cables, maybe you can put the battery in the bar end and charge port junction on the other bar end. The shifters have extra ports. That may be the best configuration for minimum cable length and connections. You then have a straight run of cable to the RD.

Very curious to see where this goes. Di2 seems to have quite a bit of room for weight reduction.

[takolino]

More like 175cm

haha, being in the US, i'm a metric noob.

[Klaster_1]

My lower Extralite Ultraspacer has failed, I suspect I should have checked for loose headset more often. Just in case, I asked Extralite for an opinion, will post it here later.

[Attermann]

they will just tell you it's your own fault.

[Klaster_1]

they will just tell you it's your own fault.

Did you have a similar experience with Extralite?

[Attermann]

cracked a steer tube and a schmolke handlebar with their stem, they told me i over tourqed it, but i have never done more than 3 nm,

[jpeterson1012]

My lower Extralite Ultraspacer has failed, I suspect I should have checked for loose headset more often. Just in case, I asked Extralite for an opinion, will post it here later.

Sorry to see that failure... FDM 3D printing is the most rudimentary form of 3D printing. It's basically a small-scale hot glue gun. You could compare it to cast-aluminum vs forged-then-machined aluminum. They might both be ABS/aluminum, but they're very much not the same. The FDM-printed spacer is significantly less durable than a solid injection-molded spacer. It's less dense (its weight reflects that), and it's anisotropic since the fuse-lines between the layers tend to debond like splitting wood along its grain. While I usually like Extralite stuff, your case clearly demonstrates a case of incompetent engineering and safety factor overhead. This spacer can be used, but only as the last spacer on top of the stem, and not under it. They should've made that point clear to the consumer.

cracked a steer tube and a schmolke handlebar with their stem, they told me i over tourqed it, but i have never done more than 3 nm,

yikes. I've been doing 3Nm on mine too. Make sure your expander plug is directly between the steerer clamp bands, as it tends to pinch. As for the 3Nm on the handlebar clamp, the printed instruction manual i received states 3Nm, but their website's PDF version now says 1.5-2Nm. That's some pretty sketchy-low torque imo... My test for "tight enough" is grabbing the hoods from in front of the bike, and giving a good push down while lifting myself off the ground (I weigh only 51kg, so YMMV). If it survives the push-up I do without slipping, I call it good enough.

[Attermann]

the paper manual i got said 3 nm, but their design will creep into the carbon when you tighten it, so i will never use something from them again.

[Klaster_1]

Shimano EW-SD50 outer isolation is ~4.37g per meter. Inner wire outer diameter is 0.9mm.

[Klaster_1]

they will just tell you it's your own fault.

Extralite sent me a new, sturdier spacer version made out of CFRP, for free. Expect scale shots when it arrives. Darimo will finally send me the IX2 stem I ordered a year ago next Monday, totally my fault for not asking about it earlier. No news about Shimano lever collars yet.

Now, about Di2.

Stock Di2 wires can be tuned with a box knife. Carefully carve open outer insulation, then ply it off, use manicure scissors to help. Three wires took me two evenings and several finger cuts.

Shimano EW-SD50 140cm weight, tuned

Shimano EW-SD50 #2 75cm weight, tuned

Shimano EW-SD50 #1 75cm weight, tuned

My early FM079 did not include Di2 grommets or cable guides, despite sporting an external battery chainstay mount. All removable cable guides are either for thick brake lines (too loose) or shifting cables (too narrow). Because I decided to route one of the cable in place of rear shifting cable, cable modification was the only choice. I cut the wire, taped one end routed it through the down tube. To join the cable back together, I bought a soldering kit, but without a rig to hold the wires in place, which resulted in a huge failure - the were super hard to solder with two hand, hanging in the air. Even though first wire came out reasonably OK, the second because a mess, so I just twisted it together and shrink wrapped (2x 1mm for small wires, 2x 3mm for both). If you plan to work on Di2 wires, just get a knife, shrink wrap and gas lighter.

Shrink wrap weight

Stock wires: 12.93g (140cm) + 2x7.24 (75cm) = 27.41g.
Tuned cables: 17.67g.

Cable guides removed:

Hongfu FM079 cable stop, no bolt

Hongfu FM079 cable guide, no bolt

The battery was wrapped in a thin plastic food bag to protect from water and wrapped with regular transparent to hold the shape. Initially, I planned to hang it with on thread from the seatpost pin and fix rattling with foam, but decided to see if foam would be enough (spoiler: it was). One narrow foam ring at the top to keep it place, easy to insert. One thick ring at the bottom to hold in place, I had to use an electronics disassembly spatula (highly recommended) to force the foam in. The battery sits very tight. Bag and foam add 1g to a naked battery.

Shimano BT-DN110, tuned, with mount

The tuned RD-R9150 weighs exactly as calculated. Changes include Carbonice pulleys, J&L aluminium pulley bolts and removal of bracket axle unit.

Shimano RD-R9170, tuned

[Klaster_1]

Today, I organized the wires and replaced ST-R9120 with ST-R9170. Lever to frame and RD to frame are neat enough, but junction area is a mess, I might consider another try. I wanted to pull the wires tight over BB shell and tape them down, but mistakenly routed one of the wires in a way that prevents this and it came out as the longest one

Another subject that bothered me was weight discrepancy between spread sheet and scales. As you might have noticed, I am quite thorough, but apparently not enough. New things went into the spreadsheet: 4g of freewheel grease for difference between calculated and measured wheelset weight; 15g of air inside the tubes; 1.5g of electrical tape. Next time anyone asks what's missing from their spreadsheet, I know what certainly is Unfortunately, scale shows 5.34kg and spreadsheet reports 5331g, so 9g remain unaccounted for or scale rounds up, will try to measure the whole bike on a kitchen scale instead, but it would be tricky without a suitable table.

Actually, I measured the tape for Di2 setup:

Tape, before

Tape, after

Current Di2 conversion savings are at 47.3g. Given I could have just tuned ST-R9120 hoods (~35g saved) and 5g come from removed frame parts, tuned Di2 isn't that much lighter than mechanical, which still had several tuning opportunities available, like Tune plastic housing or custom RD titanium springs (nobody makes those).

Last several days the weather has been freaky at 20c, and I am sitting home all day, busy with my job and working on a bike until late night. I hope to ride at least once coming weekend.

[Klaster_1]

The spreadsheet and scales now have only 3g of difference and I know what was not measured yet (left handlebar side electrical and cloth tape), which I'll do when the stem arrives. Will test ride tomorrow.