Is it safe to add dimples to the chainstay?
 

I have a Charge Plug 5 steel frame.

https://i.imgur.com/gQ5ef7F.jpg

Currently i'm riding 700x37 tyres, that's about the max I can fit. There is tons of room at the front, tons of room at the seatstay, and a bit more room at the chainstay. Problem is, the seatstay and chainstay bridges are about 2mm from the top of the tyres. I would like to go bigger, and even with 37s there is no room for fenders.

I was thinking about going down to 27.5 with 47mm tyres. More tyre volume and the ability to run fenders = heaven.

I don't have any 27.5 stuff yet, but i've done some measurements and I think the 47mm tyres would just barely fit with super tight clearance on the sides. Maybe 1-1.5mm.

I was wondering if it would be safe to add dimples on the inside of the chainstays for more tyre clearance. Would it hurt anything at all or is it perfectly safe to do?

https://i.imgur.com/Bfcf59C.jpg

The chainstays don't have any dimples on the inside, only on the outside for chainring clearance. They're slightly ovalized and pretty big in diameter for a steel frame IMO. The frame is made out of Tange Prestige tubing, not sure if that matters. It's 4130 double butted tubing.

There is a framebuilder not too far away. I just want to hear a few opinions first. :)

I assume that is the new Tange Prestige, which is not the same as the vaunted Prestige of old.

it's not 100% safe. I forget if it was on here, but I have seen someone asking what to do after they split their chainstay dimpling it. And it likely will mess up your paint. Having said that, plenty of people have done it.

I think i would try to be happy with 42mm tires

Yeah the frame is from 2015.

That's not good news. :( Sadly 42s don't fit and I can't even fit fenders with 37s. :(

I meant with 650b. Should work, right? I'm pretty sure you can find some used 42's on the 650b email list for the price of shipping just for testing purposes.

Yep, that should work.

I wanted to go as big as possible but 650b with 42s are probably worth it just for the ability to run fenders, and I need a stronger wheelset anyways.

Coming from 28s I thought even 37s are going to be overkill and I also thought I wouldn't ride in bad weathear... I guess things change. :D

I went from really large 30mm tires on my gravel bike to 37's. It really made things better on sketchy surfaces. But the 2.25" tires on my mountain bike are better yet. I guess that's 57mm. So I understand. The biggest I have gone on a road bike is 38mm, and I was pretty happy with that. Mostly because I didn't have to worry about hitting things at night since I do so much night riding on bad pavement.

I think you should consult the nearby framebuilder and see what they say about it. Back in the day, we pretty much had to dimple every chainstay, and it was no problem on tubing that isn't heat treated. I am not sure about your tubing. And I'm not sure how easy it is to get tech data on it. Even heat treated tubing will dimple.

This is the chainstay of a Kona Sutra LTD that's made out of Reynolds 853, does that mean anything? :)

https://i.imgur.com/owKeFbY.jpg

The asphalt roads where are live are horrible but my 37s are fantastic on the road. I'm starting to ride more and more offroad tho. Don't want a MTB just yet.

ISTM that *how* you add the dimples would be important. I've read suggestions here to pound on a dulled chisel with a heavy hammer, which seems to invite cracked metal along with damaged paint, but I'm not a pro framebuilder.

When I dimpled my chainstays to add a few mm clearance, Clarence for 650B tires, I used a large pair of vise-grips which had one face ground to about the shape of the outer side of the chainstay and padded with duct tape, with the side of the open end of an 8mm wrench on the inner side of the chainstay. That wrench had a nice radius for the dimple. So I squoze firmly but carefully and checked my work several times until I was happy with the job. No damaged paint or anything. :)

Not sure about modern Prestige tubing, but the original Prestige tubing from the mid-80s was heat-treated and didn't take well to cold forming after heat treatment.

Reynolds 853 is a proprietary alloy. It's possible Reynolds may have bent/indented the stays prior to heat treatment, if any.

I have found this on the Tange website:

https://www.tange-design.com/tubing_detail.php?sn=52

According to this chart the chainstay and seatstay are not heat treated.

What about the indent for the chainring, when was that done in the build process?

indenting on a heat treated stay is certainly done prior to hardening. I suppose you could anneal that part of the stay. With as radical as that dimple is on the 853 bike, I can't imagine it was done in the hardened state. I'm sure Reynolds will do that sort of thing for a volume customer.

Thanks for the help guys.

So I guess i'll either screw up my frame or not. :D

I think i'll contact a frame builder and go for it. I got the frame for super cheap and I love it, the only complaint is the rear clearance. Hopefully it works, if not then time for bigger and better things. I just wish steel all road/gravel/adventure etc. frames were cheaper. :( And most of the good stuff is in the USA and i'm across the pond...

Here are two examples of self made crimpers. Both are easier to use if the stays are still separate of the frame. I used a broom handle and a mallet the first time I needed clearance for a ring, on a built bike, and I still use this at work maybe once every couple of years. A filed down puck of steel double sided taped to a vice jaw was my next method for my hobby building. Works well enough but sure is a pain to align and hold everything. I only made these crimpers last year so I'm still learning their best manors.


Just found the shot from years ago showing the bench vice method. The wood block is on half of the stay ovalizers. Basically two mating blocks (they slide together on the nails as guide pins) with a groove for the stay to sit in. This groove is hourglass shaped to focus the squeezing along a few to 15cms of stay (depending on how much pressure) making a round stay into a round/oval/round one. This is the first way I control chain stay clearances, I'll dimple in a small local area only if really needed. Andy

Nice work, looks amazing!

I use the top part of an old pipe wrench as the forming die, and half of an aluminum tube block, all pushed together in the bench vise. Sometimes I then also work in a bend to the stay using a 2.5" very thick tube and the afore-mentioned tube block halves, again squeezed in the bench vise. Works well, though this is also done before assembling the stays to anything else.

David, do you have pictures?

I'll have to take some with the next build.