Technical How to massage? Bicycle fenders?

Got the front wheels and tires for my 31 tudor and I'm making bicycle fenders for the front out of an old 35' tire ring as is traditional and I'm using 165/80r15 tires and they are just a bit wider than the tire ring.

I've searched for ways to gently massage the ring and flatten it out a bit side to side to widen it up without distorting the metal but haven't had any luck on info. Found an old video on doing it but it had been deleted so here I am!

So anyone have any info on the best way to take some of the curve side to side out of one of these old tire rings without distorting it? This is some heavy metal.

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Split it and widen it?

 

You could place the tire ring on a stiff piece of cardboard and place a fully inflated tire and wheel assembly (with adequate width to enable it to straddle both outer lips) and use your body weight to roll the tire over the ring. I've never done it but thought about doing it a few times.

 

COULDN'T YOU PUT IT IN A ROLLER AND GRADUALLY ROLL IT FLATTER?

 

There was a old video that showed how to easily do it but like alot of things (like my 6 pack abs) it disappeared over time off of youtube.

@Budget36 , thought about that but I didn't want to add a bunch more work if there were a simpler solution.

@A 2 B that's probably the best solution to try at this point. Thanks !

@Bad Bob I thought about that too if I had a English wheel. Just run down the middle of it just enough to flatten the center alittle and move the lips out.

Thanks for the replies gents !!

 

Is the radius of the fender currently correct for the tire? Flattening them is going to change that radius. As you spread the fender the radius will decrease.

 

I think the OP is wanting to flatten them out width wise so they will cover a wider tire.

And by the way, if you were to flatten a curve, I'm pretty sure you would be increasing the radius............

 

I understand what he is trying to do. As you flatten the side to side curve of a fender (the curve width wise) you are pushing the sides out as they go out that will pull the ends of the face radius in which will decrease that radius. Its a compound curve so there are two different radii one will increase as the other will decreases and vise versa depending on how you manipulate each one.

 

Hey guys yes it wouldn't hurt if it increased the radius too. Kind of hoping to kill 2 birds with 1 stone.

It appears that if the radius would increase evenly with the width it would be perfect.

A increase of a 3/4" in width with an increase of maybe 1 inch in radius would be perfection.

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It will decrease not increase.

 

@K13 sorry that's what I meant. Yes I would be happy if the radius spread out.

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I am not sure you are understanding. As you flatten the radius in one direction the circumference gets bigger in that plane but gets smaller in the other plane, so the more you flatten it across the top the more it will curl up the other way.

 

Using a 12" long rolling pin it would be a 3 man job. One to hold/rock the fender, one to hold your feet, moving to and fro (wheel barrel style) and you hanging on to the rolling pin. Extra points for posting video! lol

 

Surely the mounting brackets will be made last, to suit the fender and required tire/fender clearance.
Roll the fenders out to the width needed, then mount to suit...........

 

Deflate a tire, stuff it in, inflate tire to spread...

 

After a little more thought, maybe a simple wedge will spread it out enough. You would have to experiment to see how much spring-back can be expected. Just my opinion, I doubt that there would be a significant reduction in radius if any.

 

Thanks guys for all the thoughts and ideas!

@A 2 B the wedge is another good idea!.

If I could find an oxy or acetylene bottle shaped like a donut I'd be set!

I'm going to try and play around with different ways this coming week if I can get some alone time in my shop. Monday I'll have the tires mounted to the wheels and mounted to the front and see how it goes.

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nobody seems to be understanding what K-13 is saying. I do a lot of vintage bicycles, a lot happens to a bike fender after 70 - 80 years. you can't just tweek them one way without affecting the other way. period.

 

To keep K-13s explanation simple , get a round plastic bucket and pull out two sides by hand and see what happens.
Yeah i know , does a round bucket actually have sides