Yes, the battery can be run inside the downtube nestled up near the BB shell with the Junction B JC41 connnector.
The bicycle is faster with the external battery cover on the downtube (although not UCI legal this way) but you needn't use the extenal battery to run the cover.

-dave

---

https://www.kickstarter.com/...bike-for-the-new-era

So then I should put the cover on with my mechanical shifting?! I'll take any free speed I can get!

---

Twitter - Instagram

I did. Just make sure you center it well, if you tweak it just a little bit it goes off to the side.

Sweet. I'll have to find it wherever it is then put it on carefully.

---

Twitter - Instagram

Yes! I used one on my DA and stuffed a CO2 and tube patch inside. It only really helps with NDS yaw, but it doesn't "hurt" otherwise.
I keep meaning to trim one to fit an AR and have the guys check the improvement if any. Or perhaps just make a one-off specifically for the AR?


-SD

---

https://www.kickstarter.com/...bike-for-the-new-era

Could it be mounted on the B10 also? Spare room is always good.

---

-shoki

That's a damn good idea to use as flat kit! Is it easy to take off? Don't have it in front of my so can't picture if it bolts on.

---

Twitter - Instagram

Short answer: No.

Long answer: I'm afraid the B10 was developed with the battery mount on the underside of the chainstay, not the underside of the downtube.
The newer generation of the B-series molds uses a below-the-chainstay U-brake, not our patented above the chainstay location. Because the chainstay location was filled with a brake caliper on the latest molds we moved the battery to the downtube which hurt the aerodynamics a bit. The solution was to develop a cover to "hide" it from the wind and because we could shape it to shield the chainrings on NDS crosswind, there was an net drag reduction/improvement in -20/0/20 sweep.

-Dave

---

https://www.kickstarter.com/...bike-for-the-new-era

Thanks Dave. Was worth a try.

---

-shoki

No, it isn't easy to take off, it requires a 2.5mm hex key which I have in my folding multi-tool I carry.
The good news is I haven't needed it.

Probably not a "race day" solution truthfully unless you're less concerned about the potential extra minute of fiddling with the bolts than the potential time savings.

-SD

---

https://www.kickstarter.com/...bike-for-the-new-era

Not a bad for a backup spare for an IM. That way no need for special needs except nutrition maybe. But for training a good idea for sure. Thanks again!

---

Twitter - Instagram

How is this done exactly? Sounds like a tricky procedure.
Thanks.

Remove the fork, slide the battery in the downtube thru the head tube.

---

https://www.kickstarter.com/...bike-for-the-new-era

Thanks Dave. You don't anchor it? It must rattle a lot.

The e-tube wires and brake housing rattle, too. I wrap it in 1/4” thick foam, add a thin zip tie around each end where there’s a groove in the battery and forget about it. It’s quiet.

Thanks for the suggestion. Maybe some double sided tape might help anchor it. The foam doesn't cause any heating issues with the battery?

Don’t tape it! You want to get it out. The internal battery was designed to fit inside a 27.2mm seatpost. I would think that would be quite a bit more insulation than some thin foam wrap.

---

https://www.kickstarter.com/...bike-for-the-new-era

Good information. Thanks SuperDave!

Me again.
So I looked at my bike (B2, 2013 6770 setup):

- I see 4 cables from the shifters into the EW89-B front junction box
- the 5th port has a cable going into the down tube
- the RD has a cable going into the frame
- the FD has a cable going into the frame
- the external battery has a single cable going into the frame near the BB.

My conclusion is there is a B junction box of some sort inside the frame down near the BB and I don't need to purchase the JC41. I've never wired up a bike with di2 though, so could be missing something. Am I wrong?

Thanks for any help on this.

If you’re planning on re-using the wires from your B2 then yes, you’ll find a JC41 in the B2 frame.

Shimano has introduced more options for wiring bicycles now since ‘13 but the 5-port A and 4-port B (jc41) remain the go-to set up for aerobar configurations.

SD

Thanks SuperDave. You're always so responsive. Felt really lost an asset when you left.

I'll cross off the JC41 off the shopping list. Now to acquaint myself with how this bike is wired and how to access the JC41. Wish me luck 😄

I have had a look at my B2 to see how it is wired. So far I have found a hole in the bottom of the bike with a plug. I found the JC41 junction box inside. This hole is 17mm wide, the BCR2 internal battery is 16-7mm wide. So I am thinking I can re-use the short wire to the external battery for the replacement internal battery and slide the internal battery in from the bottom. Otherwise, doing as suggested by SuperDave
I would either need to buy a longer cable to run from the BB to the head tube, to connect the battery to the JC41 before lowering it down the down tube OR lower the battery down the down tube and try and connect it once inside, maybe the socket on the battery can peak out of the hole in the base of the BB.
This is my first foray into di2 cabling; I need to watch some youtube videos to familiarise myself. If anyone in this thread has completed this external to internal battery conversion on a Felt, I am open to thoughts on my thoughts :)

Thanks.

Mission accomplished.

Thanks for your help Super Dave.
It was tricky getting in the internal battery down the down tube. The gear wire I was trying to feed through first to pull the battery through was getting snagged. So I used gear outter cable first, which was still tricky. Attached the gear inner to it, pulled that through and then used the gear inner (make shift di2 cable routing tool https://www.youtube.com/watch?v=ks42F8sVJoI) to pull the battery down. I used some tape to make sure it didn't disconnect too early. I also tied on some string the top end of the battery and tied that to the di2 cable attaching to the junction box inside the headtube so I can pull the battery out at a later date.
I realised later that one of the biggest snags was probably the screws of the external battery mount. I wish I took that off first. But got there in the end even though I thought I wasn't going to at some stages. This the night before a race haha.

I wrapped foam around the top, middle and bottom of the battery to help reducing rattling but didn't wrap it entirely so heat can dissipated (I should have taken a photo). It's a tight fit in there so I think that helped reduce rattling. During my race yesterday, on some awful roads, I had no rattling I could hear, good sign.

One of the hardest parts was attaching the short cable to the battery once it was in. Maybe I should have attached it before lowering but then that would snag more easily. I used needle nose pliers to grab the plastic of the battery next the cable socket and then pushed the cable in. Took a few goes, but got it. Shoved the JC41 and cables into the frame (see photo) and all working.


Thanks again Super Dave.