Dynohub cable length and autoswitcher circuit location

[russellg]

Firstly, a big thank you is in order to Martin. I finally got my autoswitcher circuit built up and yesterday I had my first run. I'm impressed. I need to tweak the R15 changeover point to stop the flicker, but all things considered it working pretty well. I'll post the build pics in due course.

That said, I only have one issue: -

I'm looking for ideas of where to actually locate the circuit. Although it's the ideal location, unfortunately it doesn't fit so well into my steerer tube, well it does fit but I really need to use a preload adjuster as my headset keeps coming loose no matter how tight I do up the stem pinch bolts. It would be alright if I could push the circuit lower down, but I'm running a FOX TALAS and it appears to have quite a severe taper down to the crown of the fork.

However, I have a couple of options in mind: -

First option is installing it inside my seatpost/seatube. Overlooking the problem of running the cable out of the post, is there any restriction on how long the wire can be from the Dynamo (DH-S501) to the circuit and back to the headlight?

Second option is installing it in the top tube. Only problem there is running the cable out of the top tube, not to mention actually getting the circuit and capacitors in the top tube!

Third option: - Modify the circuit board to make it a little slimmer and shorter. That way I can push it further in the steerer tube. Hopefully I'll be able to use stem adjuster in the top then.

The final option is to pop the circuit into one of the effervescent Vitamin C tablet containers, but I really want to avoid having the circuit cable tied to the frame somewhere, inside the frame is preferred.


The big question is about the length of the wire from the dynamo, but does anyone have any other ideas for the location?

 

[znomit]

... unfortunately it doesn't fit so well into my steerer tube, well it does fit but I really need to use a preload adjuster as my headset keeps coming loose no matter how tight I do up the stem pinch bolts.

Have you thought about a removable star nut? It means pulling the circuit and installing the nut whenever you need to adjust the tension but possibly the best option.

 

[Eamon]

First question.
What is your fork/stem/headset? Consistent loosening is an indicator of something wrong. If your LBS has not been able to fix it, I would encourage a second opinion. Running with your headset loose is a great way to break your frame.

Second. Is there any chance one of these would do the job for you?
http://www.use1.com/products/ring-go-star/

http://www.eastonbike.com/downloadable_files_unprotected/instal_instr/beartrap-EN.pdf

There is also a problem-solver part that works, although not really well. Timesport used to make something they called the "microset". Their part # was 53002934. It was the pick of the litter. I have three in long service with never a problem. It may not be made anymore, and it was never cheap.
It sounds like you almost have enough steer tube for the board, and all you would need is an external adjuster.

Eamon

 

[russellg]

Hi there, thanks for the replies,

I actually use one of those preload adjusters, its an FSA conix. Its pretty big so to save some space in the steerer I was going to use an old X-lite one, as it has a lower stack height.

The reason is that because of the internal taper of the steerer tube the dynauto circuit board will not slide far enough down, meaning there is no room for the preload adjuster.

I checked out the ring-go-star. I dont that that will work because there is just not enough clamping force for the carbon stem to hold itself in place without working loose. My original plan was to just use the preload adjuster, remove it and pop in the circuit. But it just keeps working loose. I must stress though that with a proper adjuster in place there are no problems.

I reckon my best bet is either to make the circuit slimmer, so it slides further down and I can use the preload adjuster, or mount it somewhere else.

I'm keen on putting it in the seatpost, I can't see run of cable (specifically length) being a problem.

I might try triming a bit off the board first...

Russell

 

[russellg]

I forgot to mention...

The fork is Fox TALAS RL,
The Stem is Bontrager XXXLite (Carbon)
The headset is Chris King No-threadset.

Without changing the stem I dont think an external adjuster will work. I fear it may keep pushing the stem up.

If I adjust teh headset properly with an adjuster and remove it, I can ride for a few miles (depending on terrain) before it works loose.

Maybe the best ption is to change out the stem for the dark nights, might give me a wee bit more clamping force with an external adjuster.

 

[syc]

The late, great Sheldon Brown had a good trick for threadless steerers - just use a pinch collar/clamp to secure the steerer so that you don't need any of that compression bolt nonsense. See the section, threadless without spacers.

If you can find the right sized collar, the whole length of the steerer will be available to you. I used a 1 1/8 clamp on a previous bike and had zero issues.

Steve

 

[Eamon]

Russell,
I figured that was the issue from what you said. That's why externals occurred to me. From there you could top the ST with tape, wine cork, whatever.
It's not entirely a lighting sort of answer, but 20+ years in the industry tell me that your stem is a problem. If you haven't already, pull the stem, and clean off any sort of grease that might be on the stem and ST.After doing that, I would reinstall that stem with friction paste and a torque wrench. Something is moving that shouldn't be moving.
At the last, I would invite a dealer to install that stem, and possibly to warrantee it.

I don't care much for Sheldon's rig. It's not a precise adjustment, and some headsets do care. Any sort of setup with a King headset, I wouldn't do that to.

</OT>

Eamon

 

[syc]

I don't care much for Sheldon's rig. It's not a precise adjustment, and some headsets do care. Any sort of setup with a King headset, I wouldn't do that to.

wrt to the precise adjustment, why can't you just put the clamp in place of one of the spacers, perform the load adjustment with the compression nut, then tighten the clamp to lock it all into place and take the compression nut out?

The CK headset won't care whats holding it in place, though you would probably lose a lot of bling points.

 

[Eamon]

You could,
but then you're getting into enough spacers to cover however much steer tube you're wanting to run, or a pre-cut piece of tubing, or something else. Think about applying it to the setup that Sheldon's description shows.
In Russell's case, the board would have to come out every time he adjusted his headset.

It was the "push the stem down as hard as you can" and tighten the bolts that I was objecting to. One of the reasons I'm so fond of external adjusters is that I've had to do exactly that, and found it to be a pain.

Eamon