[Viv92]

I have a flat boxxer crown. Anyway it's JUST too high. It fits on, but about half of that little beveled bit on the top of the stanchion is exposed. Basically it's about 1mm short of being right.

Can I run a flat crown for one ride and it won't destroy my forks?


One more thing, do I measure the 203mm for the bottom crown from where the forks want to sit after bouncing on them or from full extension of the forks (~5mm more).

 

[Viv92]

Crown question is irrelevant now. I stripped one of the bolts on the bottom crown.

New question, anyway to fix this without buying a new crown and stanchion?

 

[Udi]

You just stripped the bolt head right?
If you haven't munted it up too badly, it's probably not too hard to sort out provided you go about it carefully and in the right way. If you want to swing by on an evening I'm home I can probably sort it out for you. If you want to DIY your best bet will be hammering in a slightly oversized torx bit all the way into the head and then using a small socket wrench or shifter to unscrew it carefully. It helps to do up the non-stripped bolt tight enough to relieve the stripped one of some load. My only warning is that if you try this method (or any other) and don't get it out, it'll make the next attempt much harder.

Also, I'm fairly sure you would have overestimated how much stanchion needs to be exposed... the morewoood should let you run the flat crown provided you haven't got a ridiculously tall headset on it.

 

[Sghost]

When you get the bolt sorted out, should knock the travel down to 7" until you get a new crown.

 

[Viv92]

You just stripped the bolt head right?
If you haven't munted it up too badly, it's probably not too hard to sort out provided you go about it carefully and in the right way. If you want to swing by on an evening I'm home I can probably sort it out for you. If you want to DIY your best bet will be hammering in a slightly oversized torx bit all the way into the head and then using a small socket wrench or shifter to unscrew it carefully. It helps to do up the non-stripped bolt tight enough to relieve the stripped one of some load. My only warning is that if you try this method (or any other) and don't get it out, it'll make the next attempt much harder.

Also, I'm fairly sure you would have overestimated how much stanchion needs to be exposed... the morewoood should let you run the flat crown provided you haven't got a ridiculously tall headset on it.

Stack height is pretty big, almost 15cm. Headset is a King... are they tall?

 

[fred.r]

I have a buddy that will trade you his tall crown for your short if it doesn't work out. Kings are 24mm? I think... which is about standard I think. Just throwing that out there though, don't really know for sure.

 

[Viv92]

How do I set it at 7" of travel? this would fix it for the day...


Anyway I'm incredibly confused.

Udi tells me max stack height for a flat crown is 150mm. Mine is 146-147mm. I am also told you measure the travel from where the fork sits in it's travel after bouncing on it.

Now my bike shop as well as another guy who has been a mechanic for years tells me you measure it with the spring side stanchion extended as far as possible.

No disrespect to what any of you have told me, I'm just very confused. Udi, please don't take this as I haven't read your post. I have, but I'm still confused and it's even possible you could be wrong... unlikely but possible. With so many different opinions, some of them have to be wrong.

 

[davep]

Any sag amount is out of the total travel. So if you are sitting at 20mm of sag for example, the remaining travel would be 183mm....ish.

All forks have a variation in travel of a mm or so due to top out bumpers, bottom out bumpers and mfg variances.

Best way since you have a coil fork...

Pull the top cap of the spring side and compress the fork fully...add about 5mm for botom out bumper compression.

Thd flat crown will fit up to 150mm of total stack height. My guess that you can slide your lower crown down.

 

[Viv92]

Yep RS say 150mm stack height. It has to be right then, I'm sticking with the flat crown.

 

[Udi]

Now my bike shop as well as another guy who has been a mechanic for years tells me you measure it with the spring side stanchion extended as far as possible.

No offence to any bike shops / mechanics here, but most are morons. What they said above is incorrect, because if you forcibly extend the fork, you will be compressing the topout bumper/spring. This travel is not included in the fork's total travel (203mm). That's precisely why I told you to lift the fork to full travel forcibly, and then gently let it go before taking any measurements. This ensures that the fork isn't sitting into its positive travel, while also ensuring that you aren't including topout travel in your measurements.

It's entirely possible that you just misunderstood what they meant when they said "extended as far as possible" but hopefully any doubt is now cleared.

 

[Viv92]

OK. The only conclusion I can come to is the 150 stack height thing is wrong. There is no way the fork would fit with flat crown on a bike with a 150mm stack. Mine is less than that and there is no way a flat crown is getting on there with enough stanchion exposed.

 

[Wobbler]

How much less? I just measured mine (cove shocker with cane creek IS2 (I think..) its 148mm stack and I have flat crown on with about 3 mm above them till the little beveled bit on the stanchions. I set the lower crown up with a little bit of extra clearance last time I serviced them (~209mm from memory). I'm pretty sure you are measuring the stanchion exposed length wrong.

 

[Viv92]

I'm not including crown race in the stack if it matters, not that it actually adds any height though...

I'll just run mine as high as they can get on the stanchion and hopefully that'll work then.

 

[Udi]

Haha dude, the 150 stack thing isn't wrong (it's been that way for years). Like a few people have said now, I think you just measured the exposed stanchion wrong.

However yes, the stack height should include everything between the two crowns (headtube, headset, races).

 

[Viv92]

This is so confusing. I'll just run the stanchions as high up the crowns as they will go, once I get a new crown that is.

The guy who I bought the frame off was running a flat crown so it must work.

 

[andy_n]

No offence to any bike shops / mechanics here, but most are morons.

But off course Internet know it all's are soooo much more reliable. Udi, you come across as such a elitist bike guru that loves to cut people down in the anonymity of the internet.

Viv, if you want an opinion stop asking every person you know and then trying to play them off against each other. When I was at your place and you were desperate to ride on the weekend, we measured more than the 203 mm and made sure the top crown went onto at least the bevel.

 

[Udi]

But off course Internet know it all's are soooo much more reliable. Udi, you come across as such a elitist bike guru that loves to cut people down in the anonymity of the internet.

If you know me in person, then feel free to come and explain which part of my previous post/s were incorrect.

Until then though, I'm just telling it how it is. I've seen these issues and have been through it all before, and was just hoping someone might be able to benefit from my experiences (and "elitist anonymity"). The boxxer flat crown does allow for a 150mm stack height (with the top of the upper crown just below the stanchion bevel) and I was trying to explain that so that Viv could keep his flat crown - they are more valuable and are easier to trade than trade back.

If you're the Andy I know, then I'm surprised you chose the public snipe over the private argument; because in doing so you've made a personal attack and contributed nothing to the discussion. I try to limit myself to one of those mistakes per elitist, anonymous post.

 

[andy_n]

If you're the Andy I know, then I'm surprised you chose the public snipe over the private argument; because in doing so you've made a personal attack and contributed nothing to the discussion. I try to limit myself to one of those mistakes per elitist, anonymous post.

Yes it is the Andy that you know. I took it as a personal attack on me, in your post. Is isn't from what you wrote so much as you wouldn't know, but because of the fact that Viv has no idea what he is doing. Gets the facts from you. I help him measure at least 207mm just to be safe and the flat crown just fitted. Then he continues to post on the internet asking for help from people he doesnt' know when he already had the answer.

I did make a mistake when first talking to Viv in person, as I thought from when I last had boxxers, that the flat crown stack height was more like 130 mm. I was therefore quite surprise that with the 150mm (not loaded) that the flat crown appeared just to fit. He was still worried that it didn't fit well enough.

 

[Udi]

Do you work at a bike shop? Last time I checked you didn't, and that was the only attack I made (certainly didn't mean for you to be personally offended, I didn't even know you were involved). Everything else was pure facts and figures. The correct figures (straight from rockshox) are 203mm exposed stanchion, and 150mm maximum stack height to run the flat crown. The correct way to measure exposed stanchion is with the fork at full extension, however not forcefully extended (because that will eat into the topout travel, which would throw off the measurement). I did point out that "the mechanic" may have known/meant that, but I figured it was worth clarifying because Viv didn't sound too sure.

Ultimately the best way to measure is to remove the spring and bottom the fork out (as davep suggested), but given that Viv has measured the stack height (with 3mm to spare), it's easy enough to calculate without having to do that.

I know it's down to semantics now, but had you known what I did, you would have known that you could run the upper crown with all the bevel exposed above it (albeit no more) and no problems would occur. Had that been the case, this thread probably wouldn't exist.

No hard feelings!

"Minimum upper tube exposure, WC/Team/Race - 203mm"
"Use short upper crown for stack heights of less than 150mm"

 

[andy_n]

Do you work at a bike shop?

Had that been the case, this thread probably wouldn't exist.

No hard feelings!

During Uni, I did.

I only wish.

 

[Viv92]

To clear this up with both of you, I just wanted to make sure so I didn't end up smashing the dust wipers against the lower crown and having to buy new dust wipers. No hard feelings.