Knock-Block failed - Trek Rail 9.8 carbon frame damage

[MLX John]

I 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?

"The revised down tube–which they’re calling Straight Shot–is said to make the new Fuel EX stiffer than the current Remedy" - Trek

Funny, you would think their big bad enduro bike (Slash) would be the perfect candidate for this design, but they have clearly abandoned this engineering "marvel" for the Slash. Why does it have the knock block if the fork does not contact the frame now? Weird.

Carbon molds cost quite a bit of money, I think there will be bent downtubes on all of their redesigned frames in the future. Maybe they included the knock block on the Slash to kind of hide or obscure the fact that they will eventually be moving away from the straight shot downtube.

 

[Mikerb]

If you look at a supposedly bent down tube it is in fact straight but has a much bigger joint at the junction with the top tube and headtube. I suspect the rationale behind the "straight" down tube was more to do with the cost and complexity of a more complex moulding of a carbon down tube. It is clearly a much easier design to fabricate but at the expense of it being at the mercy of the fork crown. Other models without the straight down tube will have the same headset because that is the stock they bought!

 

[coregrind]

It would appear the secondary protection for the Rail frame is not very effective, since the damper knob made little contact with the armor piece. From the looks of the pics, the majority of the damage to the frame of the OP is in the unprotected area of the downtube. The area under the armor piece, now that it's removed, looks to just be paint damage. The design of the armor for the Rail seems to be flawed, with Trek doing a slightly better job with the armor on the Fuel EX.

Fuel armor:

I'm waiting for delivery of my carbon Rail and am gathering bits for some customizations. Already on hand in my spare parts are +3mm & +6mm crown race options from Cane Creek, as well as an Angle Spacer from Reverse Components that is effectively a +8.5mm crown race. I'm curious what amount of spacer height is required on the Medium size frames for proper clearance?

 

[Slapbassmunky]

Already on hand in my spare parts are +3mm & +6mm crown race options from Cane Creek

I'd completely forgotten about those spacers, what a good idea! Cane Creek P/N's BAA0855K and BAA1078K respectively.

 

[Slapbassmunky]

Right guys and gals, i can confirm the 3mm cane creek spacer will clear a medium frame with the adjuster removed. Just!

I've filled the gap left with a large o ring (not in the pics) glued to the frame. I'd rather it rubbed on the fork crown than the frame. It's flush with the head tube and looks good.

 

[Jamescoughlan]

nice one! Are you in the US? I can't find that part in stock in the UK.
Cheers

 

[Slapbassmunky]

nice one! Are you in the US? I can't find that part in stock in the UK.
Cheers

I'm on the Isle of Wight. My local shop ordered it up and it arrived within a week.

 

[coregrind]

Right guys and gals, i can confirm the 3mm cane creek spacer will clear a medium frame with the adjuster removed. Just!

That’s still closer than I expected with the cap off. My plan now is to fit a FOX 36, so I’ll have to compare the crown and cap designs for clearance differences. Regardless, I’m now leaning towards the +6mm crown race as a starting point.

Thanks for the update with pics!

 

[Jamescoughlan]

I'm on the Isle of Wight. My local shop ordered it up and it arrived within a week.

good to know, thanks for that. If only I had an LBS!
cheers

 

[Slapbassmunky]

That’s still closer than I expected with the cap off. My plan now is to fit a FOX 36, so I’ll have to compare the crown and cap designs for clearance differences. Regardless, I’m now leaning towards the +6mm crown race as a starting point.

Thanks for the update with pics!

Going on problems friends of mine have had with creaky crowns I'm not sure I'd let my bike even be in the same room as a set of 36's ?

It might look a bit odd with the +6 in there, the gap looks strange enough with the +3

 

[coregrind]

Going on problems friends of mine have had with creaky crowns I'm not sure I'd let my bike even be in the same room as a set of 36's ?

It might look a bit odd with the +6 in there, the gap looks strange enough with the +3

I haven’t had issue with my previous 2019 and 2020 forks so I don’t expect anything different from the 2021.

The look is not much of a concern for me. If it was, I wouldn’t purchase an eMTB in the first place.

 

[ekruegerv]

Ugh, just had a get off this morning and a quick google search brought me here..

I've got the exact same damage to my frame. XL trek rail 9.7, Yari converted to RCT3. Top cap damaged the carbon.

If I may ask, what ever happened with this @Jamescoughlan ?

 

[leix_toffee]

This is really putting me off buying a Trek Rail unless there is an off the shelf option to give the clearance not to have to use the knock block

 

[Gyre]

You don't design a bike with a downtube that doesn't clear the fork crown and then abandon the customer when your design fix for the problem fails its intended purpose.

 

[Jamescoughlan]

Ugh, just had a get off this morning and a quick google search brought me here..

I've got the exact same damage to my frame. XL trek rail 9.7, Yari converted to RCT3. Top cap damaged the carbon.

If I may ask, what ever happened with this @Jamescoughlan ?

hi there, well Trek showed no interest in taking responsibility for a design, therefore product, failure but they did offer me a replacement frame at cost. This was nearly a third of my original purchase price so not really a goer.
In the end I had it repaired with carbon fibre epoxy filler then applied a Kydex patch over it (with automotive grade silicone) which is pretty bombproof material.
Undoubtedly Knock Block is a total joke if the fork crown can still hit the down tube. My mates large with Zeb’s actually has clearance, the bastard!

I think their response and lack of interest is really sad but I don’t have the bandwidth to push beyond my lbs where I bought the bike, too much other more important stuff going on in the world right now.

still gutted, the bike is bloody brilliant.

 

[Slapbassmunky]

The thing is it's not the frame that's the issue, as it clears with lyriks/Yaris/36 etc. I wonder if 38's clear? Anyway, the problem is specifically down to fitting Zeb's.

I'm no law expert, but in the UK if something is sold and not fit for purpose you take it back for a full refund, no questions asked.

There are countless cases in the automotive industry of cars chewing themselves to bits due to shitty design or engineering choices. When these cars hit the second hand market no one touches them, but the manufacturer is required to fix the ones that go wrong in the warranty period.

However, Trek could argue against that because it's crash damage. I know this is going to cause crap feelings because they market the bike as an electric slash (reminds me of when I took a leak on an electric fence once ?) which is designed to get 'rad' on and inevitably get crashed hard. Clearly the knock block isn't up to standard.

The best we can do as a group is highlight this fact to as many people as we can, buy out Cane Creeks entire stock of 3/6mm spacers, and live with it. I'm prepared to live with it, the rail is an amazing bike in all other areas.

Rant over. ?

 

[Gyre]

I'm no law expert, but in the UK if something is sold and not fit for purpose you take it back for a full refund, no questions asked.

In the US we call it the implied warranty of mercantibility.

 

[Jamescoughlan]

The thing is it's not the frame that's the issue, as it clears with lyriks/Yaris/36 etc. I wonder if 38's clear? Anyway, the problem is specifically down to fitting Zeb's.

I'm no law expert, but in the UK if something is sold and not fit for purpose you take it back for a full refund, no questions asked.

There are countless cases in the automotive industry of cars chewing themselves to bits due to shitty design or engineering choices. When these cars hit the second hand market no one touches them, but the manufacturer is required to fix the ones that go wrong in the warranty period.

However, Trek could argue against that because it's crash damage. I know this is going to cause crap feelings because they market the bike as an electric slash (reminds me of when I took a leak on an electric fence once ?) which is designed to get 'rad' on and inevitably get crashed hard. Clearly the knock block isn't up to standard.

The best we can do as a group is highlight this fact to as many people as we can, buy out Cane Creeks entire stock of 3/6mm spacers, and live with it. I'm prepared to live with it, the rail is an amazing bike in all other areas.

Rant over. ?

Slight correction for you: the Zeb’s clear on a large and the Yari/Lyrik hit on my medium.

I’ll be buying a spacer too!

 

[Jamescoughlan]

Thinking about this, all MK1 Rail's came with RS Yari/Lyrik forks, Zeb only came out end of 2020 so the Trek Engineers/Designers would have 100% known that in the event of a crash, even a fairly mild one given the weight of the bike, once the knock block failed the top caps would damage the frame.
That really is piss poor. You think they'd have a robust FMEA process in place by now given their size, age and turnover.
I've just ordered the Cane Creek 3mm crown race spacer. £11 for peace of mind but disgraceful I have to go this route.

 

[Jamescoughlan]

Grr. Who bought this topic up again?! I was getting pretty zen about the damage and now I'm angry again!
Jokes.

 

[leix_toffee]

This is a very good thread to get the word out to Trek Owners and buyers to use these spacers. Thanks all for putting this here

 

[Mteam]

My orbea wild fs has a similar design, where by default the fork hits the downtube, so they've built a steering limiter into teh headset similar to the trek knock block.

Anyway - I fitted a superstar components -2 deg angleset in order to slacken the head angle, and a side effect of this is that the fork now clears the downtube.

I didnt fit the headset for this purpose, but its a happy coincidence. Might be the same for the rail?

 

[Slapbassmunky]

My orbea wild fs has a similar design, where by default the fork hits the downtube, so they've built a steering limiter into teh headset similar to the trek knock block.

Anyway - I fitted a superstar components -2 deg angleset in order to slacken the head angle, and a side effect of this is that the fork now clears the downtube.

I didnt fit the headset for this purpose, but its a happy coincidence. Might be the same for the rail?

It's a direct fit headset on the rail so a no-go. In fact, the headset on the ally Rail I demoed creaked like mad. On inspection the lower race was sat in a DIY mix of valve lapping compound (grease and grit) and had been rocking in the frame enough the cause serious problems.

When i got my 9.8 the very first thing i did was remove the headset bearings and reseat them in some low strength bearing retainer.

 

[Mteam]

It's a direct fit headset on the rail so a no-go. In fact, the headset on the ally Rail I demoed creaked like mad. On inspection the lower race was sat in a DIY mix of valve lapping compound (grease and grit) and had been rocking in the frame enough the cause serious problems.

When i got my 9.8 the very first thing i did was remove the headset bearings and reseat them in some low strength bearing retainer.

ah - I hate integrated headsets, forget my idea then.

 

[Gyre]

It's a direct fit headset on the rail so a no-go. In fact, the headset on the ally Rail I demoed creaked like mad. On inspection the lower race was sat in a DIY mix of valve lapping compound (grease and grit) and had been rocking in the frame enough the cause serious problems.

When i got my 9.8 the very first thing i did was remove the headset bearings and reseat them in some low strength bearing retainer.

I'm not sure of the Rail's specific headset dimensions, but 9point8 sells an IS angleset. They also mention Trek bikes and the knock block. Between the lift it provides and a bit of slackening maybe a good outcome isn't out of the question.

Slack-R (9point8.ca)
Knock Block (9point8.ca)

Edit: I spoke to a 9point8 rep who had this to say:

So the Slack-R does fit. The lower (and upper) cup adds 10mm of stack (each) We do not have one that doesn’t adjust the angle less than 1.2°. If you run it in the Slack-R format your fork will be far enough out and up to clear the frame in most cases. Some chunky fork crowns still contact on the fork dials. If you run it in the Steep-R format. Your fork will be closer to your frame a little and would still make contact in most cases.

Frankly, I'm a little surprised. On the forum here it looks like a +6 spacer could do the trick but 9point8 is doing 10mm and slacker head angle and according to them there may still be contact.

 

[1Nixxxo]

Merida e one Sixty has the same low downtube, but they use different solution: there’s an attachment on fork steer tube and metal limiter inside the frame. My friend did gave it loose after crash, but with no consequence. Seems a bit better solution, but still no totally convinced.

 

[Slapbassmunky]

Frankly, I'm a little surprised. On the forum here it looks like a +6 spacer could do the trick but 9point8 is doing 10mm and slacker head angle and according to them there may still be contact.

Going on my medium 9.8 the 3mm spacer allows the Zeb's to clear with the adjuster removed, the 6mm would allow them to clear with the adjuster still on.

 

[Gyre]

My orbea wild fs has a similar design, where by default the fork hits the downtube, so they've built a steering limiter into teh headset similar to the trek knock block.

Anyway - I fitted a superstar components -2 deg angleset in order to slacken the head angle, and a side effect of this is that the fork now clears the downtube.

Some relevant information here. Superstar no longer ships to the USA, so I had to get the Works Components equivalent of the same headset. On my Orbea Wild FS with a Fox Factory 38 (using the Works -2 headset) the damper dials definitely do *not* clear the downtube. I would imagine that a 3mm headset spacer would help it clear the downtube if not the bumpers, but I don't have one handy to test.

 

[coregrind]

...My plan now is to fit a FOX 36, so I’ll have to compare the crown and cap designs for clearance differences. Regardless, I’m now leaning towards the +6mm crown race as a starting point.

I finally installed a 36 on my Medium size, carbon Rail with the Cane Creek +6mm race. This effectively had a gain of 6.8mm over the stock (FSA) race. While the air cap cleared the downtube, the compression adjustment knobs still make contact. I'm not sure the additional 1.7mm the Reverse race would provide will lead to satisfactory results, so I'm giving up on the idea of eliminating the Knock Block.

 

[Willie Los Angeles]

My knock block did not protect my frame Trek Rail 9.9 yesterday. I will bring by bike today to Trek of Westlake Village and see if they have solution to protect my carbon frame on my next crash. Definitely design or manufacturing issues model year 2021 also.