Thursday, April 9, 2009

Single Eyebolt Fender Attachments - The Verdict Is In

Several days ago, while testing my newly installed Velo Orange fenders, I observed that they were significantly less rigid than fenders from other makers. Investigating this, I hypothesized that this was due to the single eyebolt attachment unique to the VO product.

To further delve into this, I sent Jan Heine, Editor of Bicycle Quarterly, the following email:

"Mr. Heine,

I'm doing a little investigation into an issue I observed while testing a set of Velo Orange fenders on a daily rider I'm building for myself. The issue is that the fenders seem to have significantly less lateral rigidity. When riding on rough surfaces, this effect of this is that the fender will frequently deflect enough to actually contact the tire.

I was rather surprised by this, as it never happened with Berthoud, Honjo, or SKS fenders on bikes I've ridden under the exact same conditions, some of which fenders were installed with substantially less clearance. So I've begun looking into this. The upshot is that I've concluded that the Velo Orange system of one fender/stay attachment eyelet results in a significantly less rigid or stable fender/stay assembly.

This conclusion is based upon several factors, the gory details of which are on my blog at First, just testing with my hand, the VO fenders installed on a bike are perceptibly less rigid when pushed side to side than Honjos or Berthouds currently installed on my other bikes. This was especially surprising for the Honjos, as off the bike, the Honjo is a lighter gauge aluminum that is readily observed to be more flexible. The second is sort of an thumbnail geometry evaluation (I have a fairly significant engineering background), that supports the idea that the VO attachment scheme would be substantially less rigid than a two attachment configuration.

The third is some historical investigation. I did some image searching of old randonneur and other fendered bicycles; all the images I found showed examples with two attachment points between stay and fender. This unanimity among the historical evidence suggested to me that the builders of yore had a pretty good reason for 2 attachment points per stay and perhaps I'm rediscovering something that was common knowledge in their community.

However, the documentation on the admittedly obscure topic of bicycle fender/stay attachment practices is pretty thin, to say the least; all I found were images, no real discussion of why things were fashioned this way. This is why I'm contacting you, to ask if you know anything about this in general, or if you know whether one stay/fender attachment schemes were ever common or even existed.

Any light you could shed on this would be much appreciated, as well as any indication of whether I can cite any or all of your response on the blog reference above.

Apropos of nothing, other than to demonstrate that the fenders are properly installed, here is the pedestrian workaday Fuji that has inspired this odd quest:

Thank you,

Jay Roberts
Silver Spring, Maryland"

I had no idea how such a cycling luminary would respond to an oddball request from a plebe schmoe like me. I didn't have to wait long to find out because, to Mr. Heine's immense credit, I received the following response 55 minutes later:

"This is one of those things I picked up in the Singer shop. One day, Ernest Csuka said: "Yes, some builders use a single eyebolt at the back. Their fenders all break, because they can flex too much."

Indeed, even the superlight bikes for the technical trials used two eyebolts to mount the fenders. (The eyebolts were custom-made from aluminum to save weight.) A broken fender incurred more penalty points than the credit for lighter weight.

So yes, you are rediscovering what the old guys had found out in the 1930s. This also was discussed in Bicycle Quarterly's article on how to mount aluminum fenders.

Please feel free to quote the above on your blog.

Jan Heine
Bicycle Quarterly
140 Lakeside Ave #C
Seattle WA 98122

P.S.: The leather washers ONLY should go between frame and fender, not between the stay attachment bolts and the fender... As you point out, they don't do anything at the stay bolts, because the stays already are flexible."

Well, there we have it - single eyelet fender/stay attachments are a questionable practice, permitting the flexibility I observed. This flexibility is doubly pernicious because it poses an immediate safety hazard as well as causing premature failure of the fender. I take pains to emphasize will cause premature failure, rather than may cause, because, as we all know, aluminum has no lower fatigue limit.

Now, beyond the fender issue at hand, a tip of the hat to Mr. Heine for being so promptly helpful. In addition to reading my email and quickly responding, the content of his response indicates he took the time to view my blog entries on the issue.

In case any readers are unaware, Vintage Bicycle Press, while largely silent on the topic of Fujis, is one of the superpowers in the vintage cycling world. I've been meaning to subscribe to their periodical, Bicycle Quarterly, for some time now, only sloth and procrastination has prevented me from doing so. I do need to get off my duff and subscribe; I urge readers to consider doing so as well.

Vintage Bicycle Press also publishes a variety of books, most notably The Golden Age Of Handbuilt Bicycles. This is, hands down, the best book ever published on vintage cycles, both in its lush photography and informative text.

Mr. Heine, should you be reading this, thank you for your prompt and helpful response.

1 comment:

Jim G said...

I mounted my VO fenders w/ 2 eyebolts per stay and they've been pretty solid. Berthoud style stays are the best, w/ a flattened section that bolts to the fender using regular bolts.