Lightcarbon: LCR018-D (endurance all-road)

[JensenMacD]

I do sit on the back of the saddle, so I agree trying to shift it forward/up is a free way to test. I also took 5mm spacer out. Lets hope the slightly greater drop and further forward COG helps. Possibly ordering an inline post and longer bar in the future.

Thanks for the help everyone, I will update once I can test.

[KRoser]

I figured it would not be the bearings but at this point, if what I did last night does not solve it, it becomes a game of trying a few things.

I initially thought may have been the 58mm front wheel but I have still got the wobble with an alloy wheel with a different tire. I do have a a bit of spacers above/below as I dial position but nothing I think is crazy. I have some extra extra hyd hose stuffed in the handle bars to give me the length I need to cut/reconnect once I dial the stack. I have the shifters hard wired, so there is 2 cables for the shifters. Again, none of that to me would cause the death wobble.

That is pretty weird, if you tried to balance wheels. Bike looks good nothing that stands out. I would try to look at that headset, I dont thing different bearings will do something, but if you are confident that your headset is correctly put together I would try to a bit more preload on the top cap to headset bearings.

I pretty much universaly preload headset bearings top cap to 2N-m, I think that is good balance for preload bearing stiffness and bearings still runs smoothly.
From what I found out that people who build bike for the first time and try to preload headset to "feel" according to internet do not put enough preload to bearings, they are just scared to tighten it too much.

So try that preload with torque wrench, I would say even 3N-m should be perfectly fine and if you tighten top cap bolt to 3N-m and your steering locks out, then there is something put together wrong.

[POTOOOOOOOO]

I've got a 0 setback seatpost and the saddle almost in maxed out forward position with 120mm stem.

So in my case I can't believe it's weight distribution.

I did however crash earlier in the race when the whole group slowed down all of a sudden. I was braking really heavily and went from nose wheely to hitting the wheel of the guy in front and then I got catapulted off the bike. Maybe that impact caused some kind of disbalance in the setup.

I've ridden about 1000km now with the bike and during the race was the first time that I experienced the speed wobble. And I have definitely ridden without hands on the bar before yesterday.

I will check it and update here.

You’re an experienced rider, but maybe chasing a more aggressive position has shifted the weight too far forward.
I know when I tested mine with a 130mm stem and more forward saddle positions it was frankly fucking terrifying - hyper sensitive front end.

I quickly went back to my usual 110mm and regular set back 😂

[POTOOOOOOOO]

I do sit on the back of the saddle, so I agree trying to shift it forward/up is a free way to test. I also took 5mm spacer out. Lets hope the slightly greater drop and further forward COG helps. Possibly ordering an inline post and longer bar in the future.

Thanks for the help everyone, I will update once I can test.

Usually people sit at the back of the saddle as it’s too low. They’re trying to make the effective length to the pedals longer.

[JensenMacD]

The first time I built it up, I did 3nm. Got the wobble and then did the 6nm LC suggests. Still got wobble. Went to 8nm last night to try that, bar moves smooth with no binding from the tightness. Possibly the fact I can get to 8nm and it still moves freely, indicates an issue with how I have it setup?

I've been sitting on the back on this bike and my other, that had a bike fit done. It's the spot that felt comfortable and avoided the rub of my retired powerlifter legs, haha. As I wait to get a bike fit done on this bike, doesn't hurt to try the forward, up and up a touch more.

[bastianb]

The first time I built it up, I did 3nm. Got the wobble and then did the 6nm LC suggests. Still got wobble. Went to 8nm last night to try that, bar moves smooth with no binding from the tightness. Possibly the fact I can get to 8nm and it still moves freely, indicates an issue with how I have it setup?

I've been sitting on the back on this bike and my other, that had a bike fit done. It's the spot that felt comfortable and avoided the rub of my retired powerlifter legs, haha. As I wait to get a bike fit done on this bike, doesn't hurt to try the forward, up and up a touch more.

Hi, but you did loosen your stem before torquing more? Otherwise you just preloaded your stem.

[JensenMacD]

Hi, but you did loosen your stem before torquing more? Otherwise you just preloaded your stem.

Thanks for checking that. Yes, both times the stem bolts were loosened so the bar could freely move. Then the top cap torqued before finally retorquing the stem bolts.

[KRoser]

The first time I built it up, I did 3nm. Got the wobble and then did the 6nm LC suggests. Still got wobble. Went to 8nm last night to try that, bar moves smooth with no binding from the tightness. Possibly the fact I can get to 8nm and it still moves freely, indicates an issue with how I have it setup?

I've been sitting on the back on this bike and my other, that had a bike fit done. It's the spot that felt comfortable and avoided the rub of my retired powerlifter legs, haha. As I wait to get a bike fit done on this bike, doesn't hurt to try the forward, up and up a touch more.

I think that could be your problem, even at 6N-m you should feel headset bearing getting a bit stiff. Think you just dont have enough gap between fork steerer tube and spacers and it all get stuck on fork steerer tube and your bearing are not getting preloaded no matter how much you tighten it.
Try to add one spacer bellow the top cap (above handlebars) to increase that gap and then you should be able to correctly preload bearings (2-3n-m)

[POTOOOOOOOO]

The first time I built it up, I did 3nm. Got the wobble and then did the 6nm LC suggests. Still got wobble. Went to 8nm last night to try that, bar moves smooth with no binding from the tightness. Possibly the fact I can get to 8nm and it still moves freely, indicates an issue with how I have it setup?

I've been sitting on the back on this bike and my other, that had a bike fit done. It's the spot that felt comfortable and avoided the rub of my retired powerlifter legs, haha. As I wait to get a bike fit done on this bike, doesn't hurt to try the forward, up and up a touch more.

It’s been talked about previously. 6nm and 8nm for a headset is just dumb. Way OTT and just not needed.
It just needs to be tight enough to compress everything so there is no movement when you pull the front brake and rock the bike forward and back wards.
2/3nm is plenty. More than that and you’re crushing the bearings.

Surely if you’re sitting at the back of the saddle you’re getting leg rub if you have big legs ?
Whatever. If you’re planning a bike fit, just get that done and ignore experimentation

[JensenMacD]

I had that concern previously and measured. 4-5mm of gap.

I agree the headset should not need that much. I was doing it to LC spec, as a way to test if it was the cause. Otherwise I would have left it at 3nm.

I was getting rub pre bike fit. When I had the last fit, I went wider Q factor and found that sitting position felt good. I probably attributing the lack of rub to the sitting position when in reality its the wider Q factor. Either way, it was feeling great on the old bike and never had issues.

I'm waiting to get in for the bike fit. It will likely be a few weeks, at best. So I want to try and get some resolution on the wobble, so I can enjoy the bike until then.

[POTOOOOOOOO]

I found moving to a T shaped saddle instead of a V shaped gave me more thigh clearance and avoided any rubbing.

I hope you get yourself sorted

[Samsonight]

Hi !

As you are talking about headset, mine has a little gap above the stem. Is it normal ?

[POTOOOOOOOO]

Hi !

As you are talking about headset, mine has a little gap above the stem. Is it normal ?

No, the steerer wasn’t cut short enough. Or change to a different compression plus with a lower stack (the metal rim at the top is a few mm thick. Others are 1mm thick and might address this)

[Samsonight]

No, the steerer wasn’t cut short enough. Or change to a different compression plus with a lower stack (the metal rim at the top is a few mm thick. Others are 1mm thick and might address this)

Ok, when I start to torque the top cap everything's good and the compression plus is under the top cap  when I've finished to torque it to 6newton it's like on the photo.

[POTOOOOOOOO]

Ok, when I start to torque the top cap everything's good and the compression plus is under the top cap  when I've finished to torque it to 6newton it's like on the photo.

Stop tightening to 6mn 🤦 it doesn’t need to be that tight.
Either everything is compressing - as it should, or it’s pulling the compression plug upwards with the stupid high torque.