Cyclist0383

Have you ever heard of a rear rack brazon cracking? Mine just did on a frame that is less than three months old. Why would this happen?

I'm depressed...

Bekologist

What the heck is all that stuff below the fender braces? What's that piece of angle iron that looks like its torquing right into the bolt in the braze on that's cracked?

Cyclist0383

The stuff below the fender braces are adjustable dropouts.

I don't understand your question about angle iron. Could you please clarify it? Thanks.

NoReg

It certainly shouldn't happen. What kind of loads were you carrying?

If there isn't perfect contact between the rack and the face of the brazeon, you can develop a lot of torque on the fitting. It should still be fine. Take it back.

Cyclist0383

I was carrying about 5kg regularly on the side that cracked. The other side had heavier loads of about 12-15kg.

I have no idea how to return it as it was bought in the States and I am in Lativa. There is no Kona dealer here in Latvia.

I'm thinking about having a buddy weld it tomorrow AM. I think the shipping will be too expensive for guarentee service.

psykelnut

and you did not have any issues with the heavier side?
i have a sutra too..
this problem has not shown up yet. i load my rear with 55lbs or more and so far i've been in some rough stuff off road.
so sorry to hear about your problem.. real bummer
hope the weld goes well
STRONG LIKE BULL!

cyclintom

I don't know what your frame material is. If it is steel then do not WELD it but braze it. It appears that the braze-on was welded on and that causes hardening of the area around the weld. This is usually "normalized" by heating the completed frame in an oven at the correct temperature for the correct period of time which relieves the stresses which caused the cracking.

If the material is aluminum you're stuck with heliarcing it together and it might well fail again. If that's the case a new frame might not be any better.

There are brackets that you can buy which replace the braze-ons but having a braze-on already there may interfere with the mounting of them.

Cyclist0383

It's Cro-Mo steel. What's the difference between welding and brazing?

Cyclist0094

in welding you heat the base metal (seat stay and rack boss) till they melt and you then add a steel filler material to complete the bond. Brazing you are heating the base metal to about 1500 degrees ( bright cherry red) then adding a bronze filler material to bond the parts together. If you have it welded the welder will need a TIG welder with the proper rod and experience in welding tubing that has a wall thickness of .06mm . It should be brazed back on.
When I look at the picture it appears the strut of the rear rack is touching the seat stay it this is so
it could be another source of your problem since the rack would be pulling outward on the rack boss. Also when you attach aluminum racks use a washer under the hex bolt it spreads the load out on the rack strut instead of concentrating the weight around the hole which is the weakest part.

MichaelW

Are you sure that the damage is to the braze or is it just cracked paintwork?
You usually attatch braze-ons using low temp silver solder.
It may be worth replacing your std brazeon eyelet with an extended one that sticks out so you can fit the rack strut flush with the end of the eyelet

Cyclist0383

Thanks to all who have replied.

What are the negative possibilities if I weld the braze-on?

Cyclist0094

The negative and likely possibly is that you will overheat the seat stay tube which will crack at the dropout in a a month or two or you will burn through it. the tubing is very thin it takes a welder with experince in that type of tubing to make a good weld, If you are thinking that a weld will be stronger or last longer, you are wrong. I have brazed on probaly 50 of these things over the years, I have never had one break loose.
Most anyone can braze. Brazing will not burn through the tube. silver braze (45-50% silver)would be nice but 35%nickle bronze will also work just fine. If you can't find the correct rod email me and I'll send you enough to make the repair.
rickc10ny@yahoo.com

sth

Before you do any welding/brazing you should contact Kona. You may have a warranty claim and trying to repair the frame without finding out Kona's position may snooker you for any possible replacement of the frame. They are a pretty good company, see what they have to say.

If you do end up trying to repair it, I agree with others here that say you should only braze it. All the hype about steel being repairable by the local welder is overblown. Modern bike steel is soooo thin that you would likely end up with a puddle of molten steel if a weld was attempted.

STH

Cyclist0383

UPDATE- I had contact with Kona and their response was shocking. Their suggestion was to switch the rack to the fender mounts which are located BELOW the disc brake. They mentioned something about the braze-on might crack again if the rack has too much weight on it. IT'S A TOURING BIKE! The pannier on the broken braze-on side mostly held my lock during commuting. No heavy weight has ever been on it. This is sooo disapointing. Kona really dropped the ball on this one. BTW, local Kona dealer thought the frame should be replaced.

Cyclist0383

ANOTHER UPDATE- I just got off the phone with Kona Europe and explained the the rack fender switch won't work. They seemed helpful and are looking into it. Wish me luck!

Flaneur

Braze-ons are fine for stuff like attaching fenders and routing cables. The eyelet for attaching the bottom of your touring rack wants to be part of the dropout casting, not an afterthought. Can't see from your pictures whether this damaged fitting is one or the other..............

NoReg

I think if this thing is really cracked, your best repair would be a simple machined fitting. 1500 degrees (not my number) is close to the trans temp for most steel, if the steel does not cool very slowly, the result is significant hardening. If you are below the trans temp, or above and cool slowly the likely result is softness. In addition, you will have significant paint damage, and a significant possibility of burning the metal. You could also weaken other braze-ons.

Even TIG welding small parts like that, they get nuclear hot, and sometimes just melt, there isn't a sufficient heat sink in the frame or part. I don't doubt someone could do it, but not just anyone with a welder can. I regularly weld 1/8" material, but when I TIG tacked together my stainless fender bracket out of 1/8" rod, and a scrap of steel, I was running beads several times, when the whole thing just separated cause some part melted out. I reduced the amps way down, and just tacked it, and it seems to be holding, though areas are rusting slightly due to excess heat. The 304 I used doesn't harden like chromo, which would have totaly changed with that treatment.

All that is required is an axle mounted bracket that will transfer the weight from your load, not elegant, but much better option than burning your bike up. As I recall, no Kona has long stayss for massive heel clearance. Fix that and call it a win win. This Burley rack install kit shows the idea. Theirs goes way back, and uses two `brazeons, but you have the stays, the fender part, and the axle to develop something from.

You can then carry on your war with Kona, until they give you the new frame you deserve. 90% chance your welding job will remove all liability from them.

sth

Very disappointed to hear what Kona said! Hopefully you get better luck with Kona Europe.

I was looking at the Sutra and to me, and likely to anyone else that looked at it, those two attached eyelets on the seat stays looked like Kona's solution for the rear rack/disc brake fit problems. Kona's answer to you is a complete cop out.

I never really liked the idea of those little barrel braze-ons.

Fingers crossed for you.

NoReg

Oops! https://www.burley.com/products/recum...ation+Kit&i=13

Cyclist0383

UPDATE: Kona agreed to replace the frame. Good on them.

It seems that you shouldn't carry too much weight on the back of a Sutra while using the rack braze-ons. They suggest a clamp for weights over 20kg, FYI.

sth

Good news, Ziemas. Restores some faith in Kona. Begs the question though: why byild a "touring" frame with weak rack mounts? Interestingly, I looked at the Kona website the other day and the Sutra was missing.

Why dont you look at rear racks that mount to the rear axle skewer? Old Man Mountain comes to mind. I think Tubus has adaptors for this too.

NoReg

Go for them. I agree the BOs ought to be up to it, but 20 is significant weight. If they were just good for 30, it would eliminate all problems. But still, 20 front and back should get you most place.

Cyclist0383

FINAL UPDATE: I went to pick up the replacement frame today and Kona sent the wrong size. I had a 58 and they sent what looks like a torn down 60. The paint is already chipped in places and the BB shell is full of grease. Oh well, I guess I'll be riding a 60.....

DannoXYZ 

It certainly looks like the fender eyelet was brazed on, it cracked right at the joint. Most likely due to the torque of the single-shear mount. Welding's high-heat would cause carbide-formation and carbon-migration at the edge of the HAZ. The resultant crack would be on the tubing itself beyond the edge of the weld.

That crack could've been caused by insufficient heat and flow of the brass all the way down the joint. A better way to attach a rack would be with a double-shear attachment. The rack's bracket would actually split into an inverted Y at the bottom and it would bolt onto both sides of that braze-on. Then the load would push linearly onto the dropout rather than torquing it laterally. Another way to do a semi double-shear mount would be to have a braze-on on the bottom of the stay so that the rack bolts on above and below the stay. Then the force from the rack would be more linear as well.

Fixing this would be really, really easy if you've got someone around who can braze. Takes about 15 minutes for that repair, including prep and clean-up time.

sth

Me thinks you wont be Kona's biggest references. Sorry to hear that.