Paging Keefer, or ML. KTM race team question

The frame definitely isn’t breaking in at 10 hours, but I think it’s all the components surrounding it making the bike feel less harsh. Probably mostly suspension components

The same weekend warriors claiming they can feel their frame breaking in are the dudes buying different motor mounts thinking it'll make them faster.

This is it. It’s all the linkages and bolts, motor mounts, bearings etc settling in. It’s definitely noticeable though if you ride a ktm at zero hours then hop on one with 10 back to back you’ll feel it. 

I ride Hondas, I just went from a 2022 with 37 hours to a 2024, got the same exact suspension set up. I am pretty picky (I can tell 1-2mm in fork height right away, for example), and it felt super similar to me, most noticeable was just fresh tires versus the ones I had with 10 hours on the 2022. After an hour the stiffness in suspension / chassis was totally gone. I don't get why folks think there is something special about steel frames breaking in at 10 hours. It has to just be the wear parts, which is the same across all bikes...

Then why does MXA always state the new KTMs need 10 hours to "break-in." 

The reason people believe it is someone, probably mxa, said it took 10 hours. Now its the gospel. Nobody will think for themselves because they "heard it" so it must be true

Admittedly if you took a brand new bike, rode it for the first time for an hour at say GH, then someone else put 10 or so hours on it, then rode it again you'd notice a difference. Not the frame being "looser" but as was mentioned, components/engine break'ing in giving it a more relaxed feel.

A buddy of mine stretched his 05 CRF450  3/4'  measured from swingarm pivot to front axle.  He had ridden it a season at the local Pro level, a national at Southwick and also over jumped a jump and flat landed very badly. 4th or 5th gear and arm pump so bad   he could not let off. he went about 197' to a flat landing and knocked himself out he landed so hard.  If an aluminium frame can stretch that much , I bet steel can too.  Not an argument , just reminded me of my friends story .  

So its possible, but I do doubt that Factory Honda would allow a frame to get to that point. 

I used to ride MTB's a ton. And I had a chromoly frame that I put around 22K miles on and it became very worn out and flexi VS a new one. I got a fresh frame under warranty and was surprised at how much stiffer it felt. The old one was flexing so much the reay wheel was rubbing. It ended up cracking at the headstay . I could never feel flex on a MX bike. I rode a 99 CR250 and loved it. But on a MTB I had a very good feel. It would not surprise me if riders can feel a frame flex and or prefer one that has some time on it.  

So you guys are saying that frames stay 100% the same, then one day they go from same as day 1 and just fail?

You’re saying FEA and stress testing isn’t real?  I understand the argument that maybe “10 hours” is just a number, maybe it’s 25 or 73 or 123 hours.  But man, these bikes aren’t the same as day 1.

FEA will show you what's undergoing the most stress and force and where its most likely to flex or break. Those red places will still be under the most load when its new or right before it breaks but that still doesn't predict how it "felt" between those two times. 

Sexton on this week's pulp show was asked what the main thing he noticed different from the Honda when first getting on the KTM and he said the frame feeling firmer and that he was working towards it feeling more comfortable...or wording similar to that.  

If I had to take a guess I would think that factory riders would just always ride on a brand new frame and set the bike up around that. If theyre riding on frames that are changing over time that would make their settings creep over time too. Teams/riders like consistency and known entities to work from. A well broken in frame would be a little different from a broken in frame which would be a little different from a barely broken in frame. All of these phases of frame breaking in would require different settings.
 

If they just always swapped the frame out after only a few rides then they have a consistent base frame setting that theyre always working from. They have access to every part they want so if theyre chasing comfort theres tons of things they can change to get what they want without having to screw with the frame. 
 

Just my opinion, but I think this would make the most sense.

Bruther, I dont know how else to tell you this..

If your frame is 'changing', you got a huge ol' problem. Period.

-Written from my work computer inside the engineering firm i am employed at as an engineer lol

The AER fork definitely gets less sticky / smoother over time compared to a spring fork which will feel mostly free when new. I assume it is mostly the air cartridge causing this. Most steel bikes have had AER forks since 2017 so that may be where the KTMs take 10 hours to break in came from. All the pivot points will have a similar thing happen including the engine.

Pop stalls are a lot more common on a 4 stroke with under 5-10 hours. Even the internal engine parts bed in and get smoother over time.

Fatigue cracks in the frame would make it soften over time of course if that is happening you are probably on a path to frame cracking at some point in the future. 

I had a 2023 FC250 that felt like riding 4x4 the first 5 hours or so. I then got a 2024 250xc, and it didn't really feel that way. The two differences in those bikes other than the engine were MX suspension/air fork vs XC suspension/coil spring fork. Frames while not identical are pretty similar. 

Maybe I’m crazy, I’ll dig for some real data. Right now I have nothing to else to prove my case…

Man, some of you guys need to loosen up and learn to read between the lines or something. When they say "the frame/bike breaks in" or "loosens up" they are referring to the fasteners, connection, suspension, all the parts that flex and pivot! It is just easier to say it the other way. As far as factory pros, I would bet none of them ride the same frame all season. And when they do swap, I would assume that factory mechanic knows what torques and such his guy likes. 

You guys should watch one of Billy Bolts recent videos when he gets a new race bike. He says something like "nice with a new bike.....well it will be once i overjump some stuff"

And then proceeds to flat land every log jump on the EX track for a good while haha

I started saying RIDIGITY instead.

I don't think so, dungey didn't for sure.

Old frames used to stretch as hell. Listening to an old several time GP champion in enduro. He suddenly couldn't close the door on his truck when he was a factory rider and wondered what was wrong. Frame was so stretched, they had to throw it away. 

This is coming from the same guys who think that torquing their engines mounts to 14 ft/lbs instead of 20 ft/lbs changes the whole bike. The dude from Luxon (Billy ?) Disproved all of their theories with quantitative data.... But it still never quite stuck. 

I always wondered what the point of me breaking in a bike is, considering that a pro breaking in a bike would be riding 100 times faster than I am, so why can't I just go balls out from the start.

You may experience certain fatigue issues with bikes I’m not aware of but just thinning through classical mechanics and machine design…

if metal stretch, problem = huge. 

Bob… don’t forget the washers behind the bolts that make your triple clamps more compliant (per keefer). 😂

I’ve lost count of the riders I’ve worked with, or heard say, that they preferred the plusher feeling of their practice bike, compared to their race bike, even though they’re both serviced the same and have the same suspension and setup.
Only difference being the hours on the bike. Make of that what you will.

They do in fact have professional level riders who break in frames for factory teams.  

I understand they ride with one frame for a specific amount of hours, and they have 24 to 36 frames they need to break in for a season.

This is not just a KTM thing, I know of at least two factory teams who do this.

Maybe there is some middle ground we are missing where both can be true?  I’ve never tried different torque specs. What I do know for sure the ktms feel less bound up after being ridden a few times. Both in the chassis/susp and engine department. 

100% the frame breaks in. An 8-12 hr aluminum frame is usually the target. I've built many race bikes using this method, rider breaks a bike in, then we swap entire bike to new bike keeping frame, clamps, swingarm together. Broke in Frame, clamps, and swingarm go to race bike. Every single part on a bike will be timed out at some point. Its all a big giant spring... regardless of how "far" the components are moving, they're still moving. If you take a coat hanger, and bend it just a millimeter back and forth, eventually, it will become weaker.

A lot of people in this thread have it figured out already, but I'll throw in a few things:

There is absolutely a break-in period for the full bike. Everything seats in, high spots are worn away from moving parts, bushings wear a bit, seals break in, etc., all over the bike. That's A LOT of parts and the rather small contribution of each part adds up quick to a significant difference in feel. This is what I believe most everyone is feeling when they say they prefer a broken in chassis vs. a new one.

One thing that I don't think has been mentioned yet, is that people who are riding a bike new, then breaking it in and feeling a difference, are doing that over multiple hours and riding sessions. It's really difficult to know how it felt brand new vs. how it felt on the latest ride. Unless they have two identical bikes, one new and one broken in that they can ride back to back, it's hard to know how much of a difference it really is. They're also likely on a new bike - different brand, different generation of the same brand, etc. than what they were on last. And during the break-in time, they're also getting used to the bike. 

Regarding the frame itself, it does break in to a VERY SMALL extent. There will be some small areas that have stress levels above yield in the as-produced frame when ridden the first time. These areas will locally yield and settle to a stress level that's acceptable. That will result in a very small geometric difference, likely something so small it's well within the manufacturing tolerances, so it's hardly worth mentioning. The metal of the frame itself doesn't soften over time. If anything it gets harder as it starts to fatigue, but it will be at a pretty small scale on localized areas on the frame, not across the whole thing. 

Finally, you sometimes hear about frames stretching. And people are offering evidence of that by measuring axle to axle or similar. The only real way to tell if it's stretched is to measure the frame all by itself in a jig, with a CMM, or similar setup. You can't measure axle to axle and know; there are a ton of other variables in that measurement. Adjusting the chain tension will throw off that measurement, and that's just one of many things that can change an axle to axle measurement. 

Can a frame stretch? Sure, but if the frame is well designed (as it should be), it's going to take a really big hit outside it's design loads to do it. Huge overjump, big crash, etc. It doesn't stretch a little more and more over time from regular use. A new frame should measure out pretty much identical to the same frame after 3 years of normal use. If it's measuring out much different, the engineers need to have a hard look at things and strengthen it up!

This is simply incorrect. Sorry. You can bend that coat hangar plenty of times as long as you do not yield it then it is fine. I don't really care what you believe lol but this thread was started to get to the bottom of some things.