Message-Id: <3.0.5.32.19990405005428.007a0740@inca.nscl.msu.edu> Date: Mon, 05 Apr 1999 00:54:28 -0400 To: bikecurrent@cyclery.com From: Pawel Danielewicz Mime-Version: 1.0 Sender: owner-bikecurrent@cyclery.com Content-Type: text/plain; charset="us-ascii" Following a discussion from a few weeks ago I mounted a Union 9430 front lamp on my bike, replacing my older Soubitez. Catching the last moments of darkness on my route I managed to test the Union thoroughly. The older Soubitez came with the Soubitez roller in a set that I bought at a local bike shop in '97. (No, they don't have these anymore.) The lamp might be one of the first halogen lamps for bikes around; from markings inside it must gone into production at the beginning of '80s. The bulb cannot be changed without pliers. The lamp in the shape of a squashed elongated cone nicely fitted in the setup in the front of my bicycle. The appearance and the model number 80 of the roller suggests that it is pretty much the same Soubitez roller that is marketed nowadays. When I used it, the roller generally worked quite satisfactorily. In the first comparison of the Union and the Soubitez, the Union seemed twice as bright. An inspection revealed that part of the difference arose from the haze that the bulb in Soubitez acquired after more than a year of use. The weatherproofing is clearly an issue with the halogen bulbs; while the Soubitez had some weatherproofing it was not quite sufficient. After cleaning, the Union was still brighter by a factor of 1.5 or more. When taken out, the bulbs seemed to be equally bright, so that the remaining difference must be attributed to optics. The Soubitez uses an elongated squashed conical mirror while Union a shallow round mirror than restricts the angles of reflection to about 45 degrees. The beam appears to be spread is sideways by refraction in the front plastic. When directed straight on, the Union beam consists of a series of horizontal stripes of varying intensity filling out an outline of a horizontal rectangle. When directed downward, the beam shape turns into a diverging trapezoid, nicely covering the path in front. In comparison, Soubitez beam is wider but has dark holes inside its outline and loses out completely at farther distances. My overall impression is that an optimal beam shape would be that of a trapezoid straight on, with a wider base than the top. Directed downwards, the beam would turn into a less divergent trapezoid than from a rectangular beam straight on, improving vision at farther distances. Of course the angle of vision is also of concern. However, when an area is poorly lit, one cannot see it at all, so it may be better to have a narrower angle than not see at all. My one more option for a lamp was an older Axa that had an OK beam shape, but the weatherproofing issue came up: I could easily blow air into the lamp. Thus, I dropped that the Axa from the consideration. On occasion, I tested few incandescent rears: Soubitez, B&M, and Spanninga. They differed quite a bit in their brightness and shade of red. B&M uses a red so pale that it gets close to white. That and a reflector give the light such brightness that it appeared blinding in darkness to a person standing nearby. I have no doubt that it satisfies DIN requirements, but I have reservations with regard to using it our area where paths are shared with pedestrians often with no street lamps around to reduce contrasts. Pawel Danielewicz