Knock-Block failed - Trek Rail 9.8 carbon frame damage

[Jamescoughlan]

Agreed, a reasonably high leveraged force through the headset with 80kg and a 780/2mm lever.

 

[Mteam]

may be worth replacing the zero stack lower headset cup with an external cup to move the forks away from the frame , so this cant happen again? Ok, so you raise the BB a smidge, slacken the HA a smidge etc etc, but might be worth it.

My bike (orbea wild fs) has a similar design, and uses an acros block lock headset to do the same thing, I was wondering about doing the above.

 

[Jamescoughlan]

Good idea but the headset is intergrated into the frame's headtube. I could have a spacer machined to go under the lower bearing race I suppose. The bike's BB is low anyway that i wouldn't see a compromise there. Only issue is that the forks steerer tube is probably too short, although even a 3mm spacer would probably work ok?!

 

[RickBullotta]

I think the problem is you crashed your bike.

I'm not sure what a 'simple washout' is but whether it was slow, not from a great height or whatever, sometimes it can still put a lot of force in to just the wrong place...

Unfortunately the knock block is just another component, not an insurance policy.

Respectfully disagree. Without a functioning knock block or other protective device, the frame design is fundamentally flawed. It's an integral part of the design and the operation of the bike. This is CLEARLY a warranty issue, though I must say I think the knock block is a bad idea and that frames/forks should simply be engineered to not have that type of interference with the fork crown.

Also, I personally would not ride the bike with that damage. Having had a headtube almost shear off once, it isn't pretty, and can lead to a lot of dental work. Thankfully I got away with some bumps and bruises but it could have been FAR worse.

 

[Madmountainman]

An interesting read and i'm in agreement with the 'not fit for purpose' group. This failing also means I won't be looking at any bike that has this sort of system as it can't be trusted. Both the Trek and Focus' new Sam2 share this feature, so they're off my list and they can tot up the loss of a sale due to this thread.

 

[R120]

Brands love to overcomplicate things dont they

 

[Like a Boss]

If you do have to buy a frameset at cost tell Trek you want a Project One paint job of your choice.

 

[seamarsh]

Approach it calmly and with a good attitude. Ask to speak to the rep or go straight to corporate and state your case. I’d be very surprised if you didn’t get a new frame.

as for threatening to get legal...only do that if you want to join the pool of douchebags that make this world suck.. that will get you nowhere except more frustration.

be persistent and have a good attitude you will get a new frame.

 

[Paul Mac]

I have every sympathy with the author.
I to have a trek rail 9.8 and luckily the knock block has saved my bike from two big crashes.
I think you've just been unlucky with the way the bike went down.
The knock block can't be unbreakable otherwise all that would happen is the next weakest component will just fail.
This would probably be the handlebars which in turn could leave the top tube hitting the ground.
I would be gutted if it happened to me though ?

 

[Bertquist]

Unless I’m missing something the Knock Block failed and did not do its job, Damage should have never occurred.
Trek should replace the frame no cost.
Reason enough for me to shy away from Trek Rail. I crash a lot and would surely ruin a frame quickly.

 

[Madmountainman]

Going way back, Mountaincycle's San Andreas, of which I still own one, had some frame failures when people started fitting triple clamps. Their answer was to modify and strengthen a new mount for a bolt on bump stop. This was machined ally with a rubber bumber that ran the full width of the frame and there was no chance of it allowing any sort of fork to come in contact with the frame. A simple solution to a problem, which Trek would appear to have put form over function by comparison and i'm concerned that Focus have followed suit, as their bump stops are somewhat similar. I think i'll stick with a frame design that doesn't require bump stops, which seems to be more of a flawed design process, as other manufacturers have bikes they've designed that don't need these protective add-ons.

 

[markfitton]

Its a mtb , surely it should be designed to crash. Ask yourself : is it fit for purpose:.
Im glad I didn't buy one , I washed out last week at cannock on the marbles 3/4 of the way down the last decent of the Monkey. When I managed to extricate myself from the tree stump I landed on the bars were back to front.

How can they build bikes that break after a simple wash out.???

 

[Philly G]

Its a mtb , surely it should be designed to crash. Ask yourself : is it fit for purpose:.
Im glad I didn't buy one , I washed out last week at cannock on the marbles 3/4 of the way down the last decent of the Monkey. When I managed to extricate myself from the tree stump I landed on the bars were back to front.

How can they build bikes that break after a simple wash out.???

100% agree. If you're going to design a frame where the crown can hit the down tube, the knock block should be strong enough to withstand the impact of crashes

 

[KeithR]

Its an mtb, surely it should be designed to crash. Ask yourself: is it fit for purpose?

Still not defending Trek, but ask yourself something else: is there any actual evidence out there that Trek bikes are worse than other brands when it comes to crash damage?

I can't find any - and I've really looked...

100% agree. If you're going to design a frame where the crown can hit the down tube, the knock block should be strong enough to withstand the impact of crashes

Same question. If Trek can honestly say that they're no worse than any other brand (and as I say, I can't find anything to suggest that Trek is any more prone to frame damage in crashes than anyone else) they can also say they are - self-evidently - strong enough.

Given that the vast majority of opinions about anything on the internet come from people who aren't happy about something, the lack of complaints about Knock Block's ability to protect the frame is compelling by its sheer absence.

People dislike Knock Block for other reasons, but not - if the internet is anything to go by - because riders are busting up frames with alarming regularity.

 

[Philly G]

Still not defending Trek, but ask yourself something else: is there any actual evidence out there that Trek bikes are any worse than any other brands when it comes to crash damage?

I can't find any - and I've really looked...

Same question. If Trek can honestly say that they're no worse than any other brand (and as I say, I can't find anything to suggest that Trek is any more prone to frame damage in crashes than anyone else) they can also say they are - self-evidently - strong enough.

Given that the vast majority of opinions of anything on the internet come from people who aren't happy about something, the lack of complaints about Knock Block's ability to protect the frame is compelling by its sheer absence.

People dislike Knock Block for other reasons, but not - if the internet is anything to go by - because riders are busting up frames with alarming regularity.

Ok, yes, the knock block may well be strong enough in the majority of cases. But even if damage is rare, is that reason not to warranty when it does occur? I come back to my Bike Yoke dropper. They didn't say because the fault is rare, we aren't going to warranty. They honoured their warranty, as they should. I believe Trek should do the same here.

 

[markfitton]

All I can say is , after reading this thread , I would never buy a trek or any other bike that has this problem. I can’t understand why anybody would. It’s got to be a design fault.

 

[RickBullotta]

All I can say is , after reading this thread , I would never buy a trek or any other bike that has this problem. I can’t understand why anybody would. It’s got to be a design fault.

Particularly with the creative design options that frame builders have nowadays (and the design tools that can simulate the physics and dynamics of a proposed design). There are other ways to solve the clearance problem.

 

[kenevonaive]

May I ask what is the size of your frame? I have a large Rail and my fork crown clears the rubber bumper when rotated with standard headset!

 

[Marke]

I sympathise with the OP. IMHO trek should just give him a new frame - how many people will read this and not buy a trek? It's terrible public relations.

I have two trek powerflys which have been great bikes so far. The only problems have been ones created by me. I have had numerous problems ordering spares from them. Their after sales service leaves a lot to be desired. I have a ktm exc off road motorbike, if i need a spare I download the parts fiche, find the part number, order the part online and it arrives in 2 or 3 days.

I need some parts for my trek bikes, I sent 2 emails to chevin cycles otley describing what i need which were completely ignored despite 2 follow up phone calls. I am now dealing with another shop who are having problems identifying which parts to order. It seems like part numbers are hard to aquire, although i know parts fiches exist. We are on about 5 emails so far.

Shame the after sales service is poor. The bikes (in my experience) are great.

 

[Doomanic]

Trek have an excellent dealer portal so if your LBS is struggling to find part numbers I have no idea why...

What parts are you after?

 

[markfitton]

Just heard from a mate today , he's just taken delivery of an 01 trek rail 9.8 XT. I haven't seen it but , I'm really hoping this isn't an issue for him. All the reviews look good and I haven't seen anybody else with an issue .


fingers crossed ...

 

[Mikerb]

I have the greatest sympathy for the OP but from a purely engineering point of view I cannot see that any headset mounted contraption could withstand the potential forces in a crash that rotate the bars sufficient to bring the fork into contact with the frame. So in my book if the fork can in any way hit the downtube the fundamental design of the bike is flawed, especially as there is no specific reason for that to be the case. I was just looking at another post on here of a Canyon Spectral where the OP want to change the headset bearings. The bottom bearing does not look like it can be drifted out past a collar that has a castellation....ie a knock block. The frame is carbon. So how is that collar fixed to the headtube?? Bonded, threaded, press fit? Which ever , if it is strong enough to prevent it rotating it will rip the carbon it is mounted on. If it is not strong enough to prevent rotation it will achieve nothing!! Stupid engineering design!!

 

[Philly G]

I have the greatest sympathy for the OP but from a purely engineering point of view I cannot see that any headset mounted contraption could withstand the potential forces in a crash that rotate the bars sufficient to bring the fork into contact with the frame. So in my book if the fork can in any way hit the downtube the fundamental design of the bike is flawed, especially as there is no specific reason for that to be the case. I was just looking at another post on here of a Canyon Spectral where the OP want to change the headset bearings. The bottom bearing does not look like it can be drifted out past a collar that has a castellation....ie a knock block. The frame is carbon. So how is that collar fixed to the headtube?? Bonded, threaded, press fit? Which ever , if it is strong enough to prevent it rotating it will rip the carbon it is mounted on. If it is not strong enough to prevent rotation it will achieve nothing!! Stupid engineering design!!

I think Trek designed the straight downtube & knock block simply to have a point of difference from other brands. They claimed the downtube was stronger if it didn't have a bend where it joins the headtube (although other brands seem to do perfectly fine). Having a straight downtube meant the fork crown would hit the downtube, hence the knock block. Irony is, at least on the L & XL Rails, the fork clears the frame anyway. I've taken a dremel to my knockblock so I can run a normal stem and spacers. I see the latest Slash still has the knock block, but for no purpose whatsoever. The downtube has a bend at the top so the fork will clear it. They even say the knock block can be removed if desired. So why even bother?

 

[Doug Stampfer]

Besides which frames with bent downtubes look very sexy. Frames with straight ones look like they should have v brakes. Mind you, you know how I feel about the Trek aesthetic designers

 

[Philly G]

Besides which frames with bent downtubes look very sexy. Frames with straight ones look like they should have v brakes. Mind you, you know how I feel about the Trek aesthetic designers

Painting your frame is one thing, but I hope you're not planning to "upgrade" to v brakes!? ?

 

[Slapbassmunky]

Just had a look at my medium 9.8XT with Zeb's, glad I saw this before my first big off! The easy solution is to remove the adjuster and screw an M4 dome head screw into the top of the cartridge. Then it has about 3mm clearance. I'm not bothered about using the adjuster, how often do you tweak your LSC? I'm amazed trek can come up with such a terrible design, a fork adjuster that can write a frame off, ridiculous! ?

 

[bluewater87]

at least on the L & XL Rails, the fork clears the frame anyway.

My zeb ultimate lsc adjuster misses the rubber bumper on the downtube and hits my frame enough to scrape through the paint (and perhaps the frame) if I let it. Enough to do some serious damage.
this is on a XL rail 9.7.

I intend to either grind down the edge of the adjuster or remove the adjuster and replace with bare screw as per the comment above.

 

[Philly G]

@Slapbassmunky @bluewater87 that's good to know about the Zeb, that fork is on my wishlist as an upgrade. I have the 2020 Rail 7 with the Yari, which does clear the down tube OK

 

[Sean0711]

My zeb ultimate lsc adjuster misses the rubber bumper on the downtube and hits my frame enough to scrape through the paint (and perhaps the frame) if I let it. Enough to do some serious damage.
this is on a XL rail 9.7.

I intend to either grind down the edge of the adjuster or remove the adjuster and replace with bare screw as per the comment above.

I’ve just taken my knock block apart to check clearance as had a little washout the other night and felt the bars go a bit further than usual, read this then sh*t myself! Made sure the standard Zeb select + on my 9.8 clears the frame (large) and it does... just. ?

 

[Mikerb]

Sounds like someone needs to come up with a soft silicon LCS adjuster to replace the ally one these forks, such that it either does no damage or gets knocked off completely without damaging the frame or fork. Alternatively is it not possible to add a spacer between the crown and head tube??