Can I drill/enlarge this hole in the bike frame to run wires

[nukezero]

So I would like to hide the wiring better on my girlfriend's bike like my bike where the throttle, e-brake wiring goes into the downtube instead of outside zip-tied.

So the frame tube itself has these holes already for routing brake lines and derailleur. Since the front derailleur line was removed, I have extra space. I need to run a wire into the tube but the connector at the end of the wire is just a tad bit too big for the hole.

I need to enlarge the hole to a diameter of about 10mm. This hole seems to be about 7mm tall. So I was thinking if I can use a dremel to shave both sides by 1mm?

Is this safe ? The black wire loom that you see below the downtube is the line I need to run into that hole, but the loom itself can be squeezed in as the wire is not that fat. The problem is the connector which is about 8-9mm in diameter (see 2nd picture).

 

[Rassy]

You have probably already thought of this, but why not just cut the connector off. Depending on your needs you can then either splice the same connector back after running the wire (Leave enough wire when you cut it off), or just directly splice the wires together and forget the connector.

 

[nukezero]

You have probably already thought of this, but why not just cut the connector off. Depending on your needs you can then either splice the same connector back after running the wire (Leave enough wire when you cut it off), or just directly splice the wires together and forget the connector.

Because there are eight mini wires inside this connector. It is a mother harness for the mid-drive kit which routes 2 e-brakes, 1 throttle, and 1 lcd control system. I certainly thought about it but if I have to resolder 8 wires, I'm positive the diameter of the after-job will be much bigger than the connector, counting each heat-shrink re-insulation of each wire.

 

[Rassy]

Yuk, that would be a nasty job, but you can reduce that bulk by making each splice about an inch away from the previous one. Might still be a problem if your wire doesn't have enough excess length.

Sorry, but I have no idea whether or not you can file out the existing hole without compromising the frame.

 

[nukezero]

Yuk, that would be a nasty job, but you can reduce that bulk by making each splice about an inch away from the previous one. Might still be a problem if your wire doesn't have enough excess length.

Sorry, but I have no idea whether or not you can file out the existing hole without compromising the frame.

yep, the wire doesn't have that much length. The connector is actually sort of in the middle between the two wires, so the connector joint will be inside the frame.

 

[MattyCiii]

Contact the maker and ask if they sell an extension cable? You could hack that up without compromising the original wire set?

Also, can you post a picture of the wire unplugged? Maybe it's a connector people recognize, and a source for an extension is available somewhere?

 

[dogman dan]

Since the hole is already there, I see no problem in making it slightly larger. I see nothing wrong with the wires worth the risk of making that hole a lot bigger.

 

[speedmd]

If you use a reinforcing metal type grommet and glue the support ring onto the tube, it should support the area relatively well. You could make one as needed and epoxy it down after running the cable through. Concept photo of some in use.

 

[cal3thousand]

Definitely make sure that there are no sharp points to the hole. A curved hole is substantially stronger than any hole with a point as the stresses move around the hole.

 

[nukezero]

This is what I need to do to the hole. I don't know if I should do it in the middle, or on the right or on the left.

Sorry for the "graphic" nature of the image, as it could convey other ideas to some people's thoughts :lol: :lol:

But you get what I mean, and what I'd need to do. I just need to do it to one hole at the top of the downtube, and one hole at the bottom of the downtube so the connector can enter and exit.

 

[nukezero]

If you use a reinforcing metal type grommet and glue the support ring onto the tube, it should support the area relatively well. You could make one as needed and epoxy it down after running the cable through. Concept photo of some in use.

Don't know if they sell something quite like that for my bike's hole. What if I use JB weld and just fill the hole a bit?

 

[cal3thousand]

This is what I need to do to the hole. I don't know if I should do it in the middle, or on the right or on the left.

Sorry for the "graphic" nature of the image, as it could convey other ideas to some people's thoughts :lol: :lol:

But you get what I mean, and what I'd need to do. I just need to do it to one hole at the top of the downtube, and one hole at the bottom of the downtube so the connector can enter and exit.

You have sharp corners on that hole and it will create stress points. Round those out!

A nice benefit of rounding out is that it would also look less penis-like

 

[nukezero]

This is what I need to do to the hole. I don't know if I should do it in the middle, or on the right or on the left.

Sorry for the "graphic" nature of the image, as it could convey other ideas to some people's thoughts :lol: :lol:

But you get what I mean, and what I'd need to do. I just need to do it to one hole at the top of the downtube, and one hole at the bottom of the downtube so the connector can enter and exit.

You have sharp corners on that hole and it will create stress points. Round those out!

A nice benefit of rounding out is that it would also look less penis-like

Alright, I'll become a dremel monkey this weekend and work this thing out. Probably should wear a mask too, don't know what kind of dust this metalloy could give off.

 

[speedmd]

Hi Nukezero

I would Make the larger hole at either end of the slot. Picture I listed is of a much larger item and was just so you understood the concept. I would Cover the entire slot with a small curved (to match tube curve) plate (tube wall thickness) with a slot perpendicular to the original slot and fits just the wire. No issues with tube strength once bonded down if the plate overlaps the tube 3 -4 times the wall thickness of the tube. Given what looks like the thickness of the tube in your picture, you may not need to do anything depending on the riders weight and how many miles you are expecting to log on the bike.

cheers

 

[nukezero]

Hi Nukezero

I would Make the larger hole at either end of the slot. Picture I listed is of a much larger item and was just so you understood the concept. I would Cover the entire slot with a small curved (to match tube curve) plate (tube wall thickness) with a slot perpendicular to the original slot and fits just the wire. No issues with tube strength once bonded down if the plate overlaps the tube 3 -4 times the wall thickness of the tube. Given what looks like the thickness of the tube in your picture, you may not need to do anything depending on the riders weight and how many miles you are expecting to log on the bike.

cheers

thanks for the help. The bike's tube is about 2mm thick. Not super strong. It is a step-through frame but it does have two parallel down-tubes.

 

[speedmd]

Hi Nukezero

I do not think you need to worry about this frame. 2mm wall is very strong tubing if made from good heat treated alloy and can take tremendous punishment.

A compromise you may want to look at, is that the connector has a relatively thick plastic jacket that can easily be shaved / sanded smaller. Even if you did this on two opposing sides, it would reduce the amount you needed to open the tube significantly.

 

[nukezero]

Hi Nukezero

I do not think you need to worry about this frame. 2mm wall is very strong tubing if made from good heat treated alloy and can take tremendous punishment.

A compromise you may want to look at, is that the connector has a relatively thick plastic jacket that can easily be shaved / sanded smaller. Even if you did this on two opposing sides, it would reduce the amount you needed to open the tube significantly.

Unfortunately, the holes are on the same side of the downtube. But one is at the top, one is at the bottom (near the bottom bracket). I'm overly ambitious when it comes to making things look nice. The bike is already pretty stealth with the mid-drive kit but I want to make it look even cleaner. Lots of people still have to ask my gf if the bike is electric, yet when it comes to my bike, they can tell it is electric due to the big motor and fish-type battery pack in the center of the frame.

 

[cal3thousand]

FWIW, I used nylon cable sheath to make things nice and clean. I have thought about cutting frames to run wires internally, but I just assume that I would compromise the structure too much.

 

[majornelson]

Great looking bike! What battery are you using?

The Townie has an aluminum frame, which at least won't rust (a problem with cutting steel framed bikes). I'm no expert but if you're only trying for an additional 3mm (which would be 1.5mm on each side), I can't believe that this would impact the integrity of the frame. Just keep an eye on it as aluminum is brittle.

You may be able to shave a tiny bit of plastic to make the cut even smaller. Just a thought...

 

[nukezero]

Great looking bike! What battery are you using?

The Townie has an aluminum frame, which at least won't rust (a problem with cutting steel framed bikes). I'm no expert but if you're only trying for an additional 3mm (which would be 1.5mm on each side), I can't believe that this would impact the integrity of the frame. Just keep an eye on it as aluminum is brittle.

You may be able to shave a tiny bit of plastic to make the cut even smaller. Just a thought...

using 36v 40 pcs of 18650 Samsung 26F cells in that electra townie bag. Managed to squeeze it in perfectly. I don't think I can shave the connector any more.

 

[majornelson]

Are you using a BMS? If so, which one?

I have a top tube townie. No electric... But I think the frame could handle a slight widening of the hole. I don't remember any extra reinforcement around the opening. Which, for me, would mean the engineers were comfortable with the tube strength overall.

 

[nukezero]

Are you using a BMS? If so, which one?

I have a top tube townie. No electric... But I think the frame could handle a slight widening of the hole. I don't remember any extra reinforcement around the opening. Which, for me, would mean the engineers were comfortable with the tube strength overall.

yes it has a BMS. I actually bought the battery pack assembled on eBay from victoriz.com. See the link below. It seems like a decent pack, Samsung "pink" cells, laptop cells. Capable of only 2C or 20A. It's actually extremely light weight, 4.6lbs and is of NCM chemistry. I offered him a low price based on the market price for each cell individually + the BMS + assembly + 3A charger.

Bafang 36V/350w mid drive require only 18A max draw. The battery pack does warm up a bit when I'm pushing the bike hard and riding like I stole it.

I will drill my girlfriend's bike this week. Funny thing is that she is the one with the Dremel and I don't have that tool, since she's an architect. I do have a corded Drill and cobalt drill bits but I think that is too much stress to the frame. A Dremel would seem less stressful.

http://www.ebay.com/itm/Li-Ion-Batt...Control_Parts_Accessories&hash=item3a51e81fc1

 

[teklektik]

With an existing slot and such a large hole, you will not be able to drill by hand - the bit will grab rather abruptly and chew up the slot and finish. You might be able to get away with a Unibit, but the initital positioning may be fairly uncontrollable. You should resign yourself to the Dremel. Depending on the relative diameter of the tube and relative length of the assembled connector, you may have to fashion a more elongated hole so the connector assembly can be inserted at an angle.

You can finish the inside edges by using a large round burr bit in the Dremel. Mixing up a little 5-minute epoxy and applying it with toothpick will allow you to build up a small smooth rounded lip on the edge of the hole to protect the wires.


I really think that drilling in this case may not be the best approach. If you have reasonable soldering skills, I would recommend picking up an extension cable for $10 and perhaps a few 8-pin miniDIN connectors or a second extension cable to cannibalize. Cut and splice the extension cable into the frame with 1" staggered splices as mentioned in an earlier post with the connectors near the mid-drive and the bars, then shorten the existing cables and add the new connectors (or cut/shorten/splice the existing cables or splice on end pieces from a second extension cable). This would give you serviceable (unpluggable) controls/controller and a captive frame harness.