Son dynamo for off sized front dropouts.

[Glenymact]

Hi there,

I have a 1974 Fuji special tourer, that i have built up as a touring bicycle and have ridden for the past 3 years. I have used a battery bank in the past but now i have the means to buy a dynamo hub. The dropouts are 100mm's apart but the slot width is smaller than what is standard. I know this because on the last set of 27.5" wheels i bought i had to file down the edges of the hub axle (just the threads) to get it to fit into the forks (online sources dissuaded me from opening up the dropout width with a file). The rear axle size was standard. I had no problem filing down the hollow axle on my wheel set because it was about the cheapest wheel set i could find. I was wondering if the hub axle is a replaceable part on the Son dynamo's, as I don't want to permanently devalue an expensive hub.

[heinrich schulz]

Poor options:

1. File the fork ends- dangerous.

2. File the SON threads!! Yikes.

3. Replace your fork with an  old style touring fork (used?) with proper slot fit.

Option 3 is probably the least expensive, (compared to wasting your SON), safest and allows for future use of forks and SON.

   

On Mon, 5 Nov 2018, 12:41 Glenymact, <mactavi...@gmail.com> wrote:

Hi there,

I have a 1974 Fuji special tourer, that i have built up as a touring bicycle and have ridden for the past 3 years. I have used a battery bank in the past but now i have the means to buy a dynamo hub. The dropouts are 100mm's apart but the slot width is smaller than what is standard. I know this because on the last set of 27.5" wheels i bought i had to file down the edges of the hub axle (just the threads) to get it to fit into the forks (online sources dissuaded me from opening up the dropout width with a file). The rear axle size was standard. I had no problem filing down the hollow axle on my wheel set because it was about the cheapest wheel set i could find. I was wondering if the hub axle is a replaceable part on the Son dynamo's, as I don't want to permanently devalue an expensive hub.

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[satanas]

There aren't really any smaller than normal diameter Q/R front hub axles that I'm aware of; they should all be 9mm. A few bikes had ~96mm spacing, but that's another matter.

What I'm wondering is whether the fork has at some point received some sort of blow with the wheel out, thus closing up the dropout slots at the bottom. This could be tested by trying to insert the end of a normal front axle from the outside of the fork, at the top of the slot(s). If it goes in there, then there's probably been some sort of blunt force trauma applied to the fork ends at some point in the past, a more common problem with long horizontal rear dropouts.

If that's the case, then it should be possible to carefully(!) pry open the dropouts with a suitable lever, for instance a large flat file. They should then be checked for parallelism with Campagnolo H tools or similar; most good bike shops and all framebuilders should have these. I'd check the fork alignment too.

This shouldn't be hard to fix unless something really weird is going on.

Later,
Stephen

[Peter White]

If the bike came with bolt-on axles, they are 8.5mm, if my memory is correct. I think that's the simplest answer.

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Peter White

[Glenymact]

I had some misinformation in my first post. The bicycle has 27" wheels not 27.5" (mtb). It's an old 10 speed road bike with bolt on axles. I attacked the front forks with my micrometer and i believe that 8.5 mm is correct (readings between 8.6-8.8 in the dropout slots). The question now is what to do with them. In my mind 0.5 mm isn't to much to remove from the dropouts, its just a shame I will have to expose the steel which is currently (mostly) chrome plated. I'll model the dropouts on my computer and do an FEA analysis just to make sure the safety factor isn't impacted to much.

[Old Coot]

Unless I'm mistaken, the dropouts are the strongest steel parts on the frame unless they are the cheap squeeze together  tube type which may be the case on a bike that came with bolt on wheels instead of quick releases.  A forged dropout is a solid piece of good steel, and filing a bit off of it wouldn't hurt IMHO but I can't imagine that they would somehow be bent inward in anything short of an impact that would have destroyed the fork and possibly the frame.

I'll bet a new (used) fork might be your easiest and safest solution.

Dave

[Peter White]

On those bikes i wold be surprised to find the dropouts aligned correctly. It probably came from the factory that way. I see no harm in having the dropouts properly aligned and removing .25mm from each side of the slot. A few strokes of a file on each side and you're done. Also, no need to worry about the chrome. unpainted dropouts invariable lose the paint from most of the surface after a while. If you're concerned about rust, just put a bit of grease on the surfaces.

PJW

[heinrich schulz]

Except that:

It's very easy to nick with a file-almost as easy as a computer analysis.

And old frames/forks can be had very inexpensively or for nothing. Granted harder to find forks for 27 inch wheels than with 28 inch (700c) although I happen to have an old Fuji road bike with 27 inch wheels and 9mm dropouts.

Also  I had an inexpensive mild steel frame with a cheap fork. I replaced the fork with a new Chromoly touring fork with front pannier attachments, new bearings and perfect trail for touring, which transformed the bike to an excellent tourer. (It has been said that the fork is the bike). Which begs the question, which Peter is hinting at, why put a top end dynamo hub on inexpensive, poor fitting forks.

[John Thurston]

On 11/6/2018 5:52 AM, Glenymact wrote:
> In my mind 0.5 mm isn't to much to remove from the
> dropouts

Agreed. If it were mine, I'd confirm the fork is aligned and
then file 0.5mm off the lower surface of the fork's dropout.
I'd use a flat file for the bulk of the work, and a
half-round to smooth it into the top of the slot. As long as
you don't touch the upper surfaces of the slot, you won't
affect the axle position.

A little dab of black paint will protect the fresh steel
from rust. No one will ever see it behind your axle and
quick release handles. If you want to avoid the black paint
(or bit of grease), hit that surface with a bit of clear
polyurethane or finger nail polish.

--
John Thurston
Juneau, Alaska

[Glen MacTavish]

Thank you all for the useful advice. I know its an old cheap bicycle, but I like it. I will eventually be adding a nicer wheelset that is 700c once the aluminum rims are worn on the current 27" set. It's got heavy steel tubes which make it good for touring (soaks up a lot of road vibrations). In the end I will be carefully filing down the dropouts.

regards,

Glen.

[Steve Weeks]

Just a heads-up on the planned change from 27" wheels to 700c... You'll probably need longer brake calipers to accommodate the slightly smaller wheel diameter. Longer calipers may have less mechanical advantage and consequently less stopping power.

As far as keeping the modified dropouts from rusting, the first time you ride the bike any paint, nail polish, etc, that you put on the inside of the dropout will be scratched, scuffed and otherwise breached. The light coating of grease mentioned earlier would be more effective.

[Palmer]

Hi all,

A timely post for me, even though it was started months ago.

I have the same issue with both of my Fuji Finest (72 & 74). The son deluxe will mount normally in all my other bikes, Viscount Aerospace,  Mercier 300, AD Olympian, and all the 80's bikes. These Fujis came with quick release hubs and tubular wheels- no bolt on hubs. The fork drop out is just tighter on the Fujis. I will probably go with the removing a little from the front and back of the dropout, but would rather not.

I have no trouble mounting more modern wheels on them- a touring wheelset from late 80's and a shimano 105 hubbed wheel, which is the same era as the Son deluxe.

I thought there may have been damage to the first bikes fork, but two for two makes me believe they were made this way.

Thanks all for the input.

Tom Palmer

Twin Lake, MI USA