Luna Fixed Bike DISCUSSION THREAD

[Downbeat]

Mystery solved. One of the chainring screws loosened and fell out. The freed nut was captive against the motor, and got caught because of the tight clearance.

[Downbeat]

Update: Lifted the rear wheel and spun it backwards and heard some clicking noise from the motor/clutch. Now the pedals won't turn forward OR backward.

[Downbeat]

Just got a strange issue with my fixed stealth bike: Rode over a REALLY bumpy wooden pedestrian/bike bridge, and when I got to the other side I couldn't pedal forward. The crank just stops, like there's a metal stopper. I can back pedal, but going forward it's locked up.

Any idea what happened?

[ludwigmace]

It might be about a half pedal for me but maybe less. I know that if I need to get a real quick start and I don't want to stand up in the saddle I'll gear down to a 1 and up the assist to a 3. I take off like a rocket.

[hova414]

Does the motor on the Fixed kick in immediately, or do you have to give it a half crank before it engages? I've seen both out there on the internet. Curious what folks in this forum have experienced. Thanks!

[paxtana]

Yes, it is compatible.

[boxiv61812]

I am seeking information on whether the 36v Luna advanced charger is compatible with my bike. Specifically, I would like to know if it uses a barrel connector of a certain size. Unfortunately, there is very little helpful information provided on either page.

Can anyone kindly provide me with the relevant details or direct me to a reliable source of information? Thank you in advance.

[davidol33]

The rear hydraulic brake line failed on my large size frame. Hopefully my repair experience/advice will be useful for others.

As others have commented, the rear (right lever) hydraulic brake line is too short, especially on large frames. For me this meant the plastic sleeve that slides over the compression fitting nut wouldn't stay in place and I was kinking the hose against the fitting as I rode. I eventually taped the protective plastic sleeve in place but after 1500 miles I arrived at work with no rear brakes and fluid pouring out of a tear in the top of the hydraulic hose right where it goes into the lever mechanism.

Since I see hydraulic brakes in my future bike needs I decided to invest in the tools and expertise needed to DIY this repair.

Repair Rating
I would rate this as an advanced skill repair. It requires belt removal, crank removal, drive sprocket removal, crank motor removal, fishing hose through the frame, belt tensioning and more beyond the simple hydraulic hose termination and bleeding. Took easily 4 hours and I had previous experience with belt and crank motor removal. IMO the crank motor removal is required. I tried fishing the hose using just the opening under the crank motor and had no luck in either the chain stay or down tube direction. Everything is a tight fit down there!

Repair journal

Parts needed:
Tektro 5.5mm connect hose kit (2m hose and fittings to terminate 2 ends). Myhose kit was labeled '10 Ø5.5mm connect hose kit'
Hydraulic brake bleed kit. (Generic kit had everything I needed)
Full bike repair kit including hex keys and torx keys for various brake/crank components as well as splined bottom bracket tool that fits the bike.
Brake mineral oil.

Recommended additional tools:
Tektro TRP Advanced Bleed Kit which includes fittings, cutting tool, press tool for inserting barbed fitting as well as bleed tools.
Rotating bike stand.
Isopropyl Alcohol (for cleanup)

Step 1: Remove the failed hydraulic hose
The rear brake hose runs into the down tube, under the crank motor and out the left-hand chain (belt!) stay to the rear brake caliper. This is a tight fit all the way through and after many attempts here was the successful approach:

1. Cut the hose between the caliper and rear chain stay (keep rag under as fluid will leak out). Remove remaining hose from caliper by backing out compression fitting nut. Discard these parts as they are single use.
2. Remove cranks, drive sprocket and crank motor, sliding it 3/4 out to the non-drive side to get access to the hose that passes under the motor. The online manual has a good guide on removing the crank motor. You will need some specialized tools so read through that guide before jumping in. Rocking is the secret to getting the motor to move slowly out non-drive side.
3. Once the motor is not covering the hose, pull it out from the chain stay from the crank motor side... It is a tight fit and will bind up but working it back and forth should have it out quickly.
4. taking the end of the hose the comes out the crank motor opening, cut a hole in the hose so a string can be threaded through the hose and tied in a compact knot. (strong small diameter string is good here as there isn't much clearance when fishing the hose through the down tube). I shaved the top 1/2 of my hose away so the 1/2 section of hose (with hole) plus string wasn't wider than the full hose.
5. pull the hose up and out from the opening near the top of the down tube being careful to guide the string into the opening near the crank motor. Done right this will remove the hydraulic tube from the down tube but a string will come with it allowing the new tube to be fished up past the batteries and to the brake lever later.

Step 2: Running the new hose from the caliper to the brake lever

1. Insert the new hose into the opening in the chain stay, working it back and forth until it comes out into the crank motor area (crank motor out of the way from previous steps should make this part easy).
2. Pull all the hose through to the crank motor opening except the hose needed to reach the caliper. At this point I installed the fittings to the caliper end of the hose and attached the hose to the caliper.
3. cut a hole in the new hose end that comes out the crank motor opening, tie the string through this hole and then carefully feed the tube into the down tube, using the string to pull the tube up past batteries and out the opening near the top of the down tube.
4. Carefully shape the hose in the crank motor area so it will pass under the motor and slowly slide/rock the crank motor back into place making sure no tubes or wires are pinched. When complete the new hose should be visible through the opening in the crank motor area
5. Worst part is over (hopefully)

Step 3: Attach the hose to the brake lever assembly.

1. Measure the hose length to have a nice gradual curve that brings the hose straight into the brake lever assembly while also allowing handle bar movement to the extremes without stressing the hose lever connection. Mark this length with some tape and then cut the hose with the Tektro tool or a very sharp knife and cutting board (worked for me).
2. Install the plastic protector, compression nut, compression sleeve on hose.
3. Install the barbed o-ring fitting in the end of the hose.
4. Use the Tektro tool to push the fitting all the way into the hose. If you don't have the tool what worked for me was to wrap the hose in a thick fabric napkin, hold the hose tightly with pliers (protected by the napkin from direction crushing) and then tap the fitting into the hose using the flat surface of a wrench. It took several resets of the hose out of the pliers/napkin but each time the fitting was a bit further in.
5. Once the fitting is in place, carefully insert the hose into the lever house until it seats deep in the housing, slide in the brass compression fitting and compression nut and tighten to recommended torque (see Tektro videos on this). Not having a torque wrench I did this until I felt the compression would have taken place which was not super tight...if it leaked I could always tighten more...
6. Slide the plastic hose protector sleeve over the compression fitting nut. It should stay in place without taking much load/stress (since the tube now enters perfectly straight!)

Step 4: Fill the line with hydraulic fluid and bleed the brakes (This is surprising hard and I 100% failed first try. ).

1. Use the 2 syringe method for this repair. There is far too much air in empty lines for the 1 syringe and bowl method I tried first. 20ml was enough fluid
2. http:// https://youtu.be/hJfYiDSsjZ8 (Tektro brake bleed on youtube) is the procedure I followed. The key is to use the 2 syringe method (start with full on the caliber and empty on the brake lever assembly). Then cycle back and forth until a caliper to lever flow has no bubbles. For me this required 5 cycles!! Always do an extra cycle was the advice I got.
3. Another thing I missed was to use my rotating bike stand to position the brake line as vertical as possible (and adjust the brake lever assembly to be level at the bleed port). With the bike angled like this bubble migrate to the top and out much more quickly.

Hopefully a long lived repair based on the correct hose angle and what appears to be a higher quality hose in the Tektro kit.

[a82912]

It seems to have come up before but was "out of scope", anyone figure out if this motor is available from anyone except Luna? I'm very interested in buying the bike because the price and features seem about perfect for me, but being as the Luna page for spare motors is currently listing it out of stock and so many people have had problems, I'd feel a lot better if I knew that I could swap in some motor that was likely to be available long-term. (Is it maybe just a standard form factor that other manufacturers also use?)

[Kenjeet]

It was the temp sensor shutting off the motor automatically. I'll try the lower gear today.

[paxtana]

Yes I think it may do that if it gets dangerously hot. I would probably put it in a lower gear if it was not already, and possibly scale back the power level. Could be you ran out of power too, might try charging it.

[Kenjeet]

Has anyone experienced overheating issues? My commute to work has 600-700 ft of elevation gain in 3 miles. Temp in the upper 80's right now. I had the bike in assist level 3 on the steeper parts of the climb, and about 200 yds from the office the bike died. Screen will not turn back on. I've tried unplugging and reconnecting and nothing happens.
Does anyone know if the bike will auto shut off if it gets too hot as a safety measure?

[paxtana]

A bar is a bar, long as you got the right size or have shims to make it work with the stem should be good to go. Your local bike shop would probably be happy to swap it over for you if you want to just take it there and have them pick out whatever you need.

[Kenjeet]

How would one go about replacing the factory bar and shifter/brakes with a drop bar and road bike shifter/brakes? Are there compatible shifters with the nexus hub?

[paxtana]

Sorry that is outside the scope of the services offered at this time