The tape is probably to attach the bent-wire thorn catcher to the fork. Here's a detail shot of the rear brake on Antonin Magne's 1934 TdF bike, showing how the thorn catcher is taped to the stays:
http://www.wooljersey.com/
Sometimes one or two small clamps were used instead of tape, and sometimes the clamps were taped-over to protect the rider from sharp edges in the event of a fall. Interestingly, there is no front thorn catcher on Magne's bike.
Now then... what's the purpose of the dark tape ABOVE the rear brake on Magne's bike?
Aldo Ross
Middletown, Ohio
<Classicrendezvous@bikelist.org> Cc: <aldoross4@siscom.net> Sent: Tuesday, November 15, 2005 7:07 PM Subject: Re: [CR]Fork taping, why?
> May be for a light clamp?
> Ted Ernst
> Palos Verdes Estates,CA
> ----- Original Message -----
> From: "Neill Currie" <neill_currie@comcast.net>
> To: <Classicrendezvous@bikelist.org>
> Cc: <aldoross4@siscom.net>
> Sent: Tuesday, November 15, 2005 8:54 AM
> Subject: [CR]Fork taping, why?
>
>
>> Aldo wrote:
>> ---------
>> Early Weightloss
>>
>> I've posted this before, but here's a pic of Andr=e9 Leducq
>> at the 1935 TdF... note the drilled brake levers. Lighter
>> weight, or better grip?
>>
>> http://www.wooljersey.com/
>> -----------
>> Neill asks:
>>
>> Looks like he has tape on the non-driveside fork blade too, up near the
>> crown. Whatsupwidat??
>> ------------------
>> Neill Currie
>> Hillsborough, Nh, USA.
>>
>> My blog, bike related, I think, is at http://blogericious.blogspot.com/
>>
>> The Mountain Goat bicycle website is located here:
>> http://www.geocities.com/