My experience with a few pairs of Bont's, including the Zero, is that the molding claims are mostly marketing BS. Even heating in an oven and going above the recommended temp, and even with a heat gun on low, I could never get them to change much at all.
So to answer your question, if you heat them based on the recommendations from Bont, you shouldn't hurt them. BUT, IMHO if they don't feel good on you out of the box, then chances are no amount of 'heat molding' is going to change that.

My Bonts always feel perfect right out of the box.

 Mine feel perfect out of the box too, so i won't mess with them

I second this sentiment as a wearer of Bont shoes for the last dozen years. One thing however, that you might notice while standing on them when trying them on, is that you feel pressure on the arch of your foot. I've only felt this off the bike, standing, it's never something I've had to deal with on the bike. I think when we stand on cycling shoes, we put a different type of pressure on the shoe.

The last thing everyone does out of habit is walk in the shoes. Don't do this, it makes no difference as far as how good of a shoe they are for you... your heel will feel like it slips out of the shoe, which it will because your heel lifts, and the shoe doesn't bend with it like a walking/running shoe.

Great shoes, but like anything, they're not for everyone. Don't waste your time going through the heat molding process if they don't feel comfortable. Or if they do.

At least 6 pairs of various Bonts. Never tried to heat mold them.

I've had 4 pairs of Bonts now and the Zero+ was the only one I tried heat molding. Honestly, I couldn't tell a difference and I've never had an issue with Bont out of the box.

I’ve had Bont speed skates and molded them quite well. There are parts of the fit that are amenable to molding and others that aren’t. You can’t make the shoe wider, longer, or change the arch. With skates you can definitely push out against hot spots or areas that compress in focal ways. My experience is that oven heating isn’t great, I couldn’t get them warm enough. I took my skates to a professional fitter who used a heat gun pretty aggressively. Then they were pliable with your hand or something blunt like a spoon. But, the resin they use with speed skates may differ from bike shoes slightly so YMMV.

I've had to go medieval with a heat gun on a couple of pairs of Bonts. They seemed not the least affected by the oven heat process done to prescribed temperature.

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Genetics load the gun, lifestyle pulls the trigger.

I have two pair of Bonts, and I have successfully heated molded both pair. I have slightly wide feet, and two different sizes, with the right foot being a full size smaller, If I fit my left foot, the inside-back portion of my right toe is too far back in the shoe, and I develop a very painful hotspot after 2 or 3 hours of riding. The Bonts allow me to reshape that portion of the shoe. I also push out the outside of the toe box on the left shoe.

Bont says to heat the shoes at 160F for 20 minutes. Any higher temperature will void the warranty. I have found that 20 minutes at 160 doesn’t soften the shoes at all. I heat mine at 190F for 30-40 minutes (or longer), and the sides of the foot bed become slightly pliable. I work the hot spots with my thumbs, or use the butt end of a screw driver to push out the hot spots. The results are unbelievable - they are like custom shoes. I also use G8 Performance insoles to get a custom fit for my instep/arch.

NOTE: AS I STATED BONT DOES NOT RECOMMEND DOING WHAT I DID! I REALLY DON’T KNOW IF THIS WILL DAMAGE YOUR SHOES, SO PROCEED WITH CAUTION. That said, it has worked great for me.

I had Bont Zero +. The sizing was perfect, but the problem is that my pinky toe was in pain after riding.


I don't have wide feet, though - all my running shoes are M.
I molded it several times in an oven, but it didn't make things better, so I switched to Garneau Tri Air Lite, and love them - they have an adjustable area near the toes.


//edited:
I've just checked that there are Wide Bont Zero+. Maybe I should have gone with those.

I can say that Bont will urge you to use their sizing calculator.

I did and need a wide. Also some shoes are on different lasts which may make a difference in sizing. Like a bike, the numbers are important.

I have 3 pair custom Zero+
2 pair custom Vaypor G
1 pair Ryot

I have to agree with this. Never tried their bike shoes but I've had several of their skate boots. Very poor results trying to heat mold them. Very disappointing because ill fit is killing my love of skating.

Interesting responses here. Sounds like a lot of folks don't think the heat molding does much. My experience is quite different.

I've had 3 pairs of bont shoes that have all been great with heat molding. But my particular feet are a good use case for it. I have a really prominent 5th MTP joint that tends to hurt in most cycling shoes. The Bont shoes feel almost unwearable out of the box.

Here is what I do (learned this trick from an orthotist who used to work in our clinic):

1. Put the insoles that I'm going to use in the shoe. Yeah, they probably shouldn't be heated, but it seems to be fine.
2. Start with a cold oven.
3. Put a big dutch oven full of cold water in the oven to keep it from overshooting the temperature I'm aiming for too quickly.
4. Hang a meat thermometer with an external monitor from the handle of the dutch oven so that the sensing tip isn't touching anything.
5. Put the shoes directly on the wire rack
6. Close everything up and set the oven to 160
7. When it is fully heated, it won't be exactly 160. But start the timer now.
8. Adjust up or down a smidge to try to keep it as close to 160 on the thermometer as possible.
9. At 20 minutes, take the shoes out and use the handle end of a screwdriver to push out any spots you are worried about pushing too hard on your foot. For me that is anterolateral toe box and a bit under medial mal. But whatever.
10. Shoes back in the oven for another 10 minutes
11. Put on some medium thickness wool socks (less likely to burn your feet)
12. Put a towel on the floor
13. Take shoes out of the oven, put them on and cinch them up as tight as you can
14. Stand on the towel for 10 minutes, then take the shoes off
15. Let them cool completely before mounting cleats

Again, this works great for me and is only marginally more involved than how Bont describes doing it. Plus it helps my insoles fit perfectly in the shoe.

Andy