220 rotors and trek warranty

[Sfs1973]

Hey guys. Looking to upgrade to a Magura MT7 with the 220 rotors. I thought I should double check with Trek to see if this would be in conflict with the warranty so called the 1-800 number

I didn't get the greatest answer from Trek as it seems like a bit of a grey area however the person on the phone ultimately said that it would go against warranty.

I'm sure some of you have tried a 220 on the bike and I was wondering if you have had any kind of issues. Thanks so much!

 

[Planemo]

I really don't understand the nervousness of the riders or the unwillingness of the manufacturers to be so tetchy about bigger discs. I am clearly missing something because IMO a good 200mm disc setup can stand a bike on it's nose from any decent speed. Hell, even a very good 180 setup will manage it. A bigger disc can't do better than that because a bike on it's nose is already at it's maximum torque potential.

Of course bigger discs can disperse heat better, therefore can repeatedly stand the bike on it's nose, and they generally provide more modulation with less lever effort, but all of these things I see as a benefit rather than a concern re warranty issues.

For the rear the situation is even more odd because just about anything 180 and over can be brought up to lockup point up at will, so again already maxed out re torque.

In short, I don't see any way a bigger disc can exert more stress on a bike which is already capable of maxing out stress levels to the frame/fork anyway. The benefits I see for big discs (and they are good ones) are rider focused but I can't for the life of me see they would threaten reliability. It's not like we are going from a ropey old Sturmey Archer hub brake on a Flimsolite frame to a 220 disc setup.

 

[R120]

Personally (I am by no means a super sensitive to set up pro rider) I could tell the difference on my Lyric Ultimates with how they flexed more under heavy braking when I went from a 200 to 223 rotor. The new big rotors give crazy levels of power when set up right, I have been running 223’s up front for nearly 2 years now and wouldn’t go back.

I now run Zebs and unsurprisingly they are affected far less, but from my experience the bigger rotors definitely put more stress on to the bike.

 

[Smittylube]

220 f&r for me. Works killer..

 

[Planemo]

from my experience the bigger rotors definitely put more stress on to the bike.

Ya canne defy the laws of physics Captain

Either that or your old brakes were sub par or simply weren't squeezing the lever hard enough

 

[Sfs1973]

Thanks for the responses!

I also contacted Rock Shox regarding putting a 220 on the Yari and was told that it's approved for the large disc.

My friend who also rides a Rail put on 220s, I gave it a test ride and it was clearly far better. I absolutely could feel the difference.

I think I'm gonna pull the trigger and do this upgrade.

 

[Stihldog]

My neighbour and I both have Rail 9.7’s and installed the mt7’s with 220mm rotors in the past couple of months. His riding style is ‘more betterer ’ than mine. He’ll ride double black and I’ll occasionally ride single black diamond. We both agree that mt7’s are a huge improvement for our trails. Long decents are less of a concern.

However, the LBS discovered a cracked rear triangle on his 9.7. They were uncertain whether the larger rotor caused the crack and they are having discussions with Trek regarding a warranty claim.
IMO, I can create more torque, during a steep climb while peddling for 20+min. I have a small rear fender that rubs/buzz when I apply excessive torque during climbs. Not really a concern. But never buzzes while braking with the mt7’s.

I installed the mt7’s on his bike and never noticed a cracked rear triangle so we don’t really know whether the crack was there before the install (he’s an aggressive rider) and perhaps over time his bike would become un-rideable.

We’re not taking advantage of warranty claims as the history on both our bikes prove. I’ve had to replace my rear triangle last year (operator abuse) and he has recently replaced his dropper (operator abuse).

We’re both happy with the mt7’s and other eMTB’s around us are making the upgrade. Our trails and this mountain can be fairly harsh on an average MTB so upgrading some of the components is necessary.

 

[R120]

One thing I think, and to be clear I have no engineering expertise, but it makes sense to me that for example on the likes of the Zeb fork they are designed for a minimum 200mm rotor, and as such the adapter you run for is 220/223 isn’t that big or stressed.

if you are running a big rear disc on a frame with a 180mm mount, you are running a bigger adapter and presumably putting more force through that as a result.

No idea if it makes a difference or not, but if I was running a big rear disc I would be hot on checking the mount before every ride.

for me the advantage of running the big rotor up front is that it can bail you out of “ohh shit” moments.

200/203 rotors are perfectly capable of doing the job of you are riding well, but for me the 223 has saved my bacon when I have been coming into something too hot or made a mistake.

 

[Doomanic]

I also contacted Rock Shox regarding putting a 220 on the Yari and was told that it's approved for the large disc.

That's a relief, I've been running a 223 for 18 months...

 

[Slapbassmunky]

Thought I'd better add my experience. I talked to Trek UK, they said 220 rear would be 'fine' on the ally frame but not on the carbon one. Something to do with how the carbon is laid up and the amount of braking torque on the upper bolt. The guy I spoke to was actually really helpful.

 

[Smittylube]

Alu 7 here.

 

[Sfs1973]

One thing I think, and to be clear I have no engineering expertise, but it makes sense to me that for example on the likes of the Zeb fork they are designed for a minimum 200mm rotor, and as such the adapter you run for is 220/223 isn’t that big or stressed.

if you are running a big rear disc on a frame with a 180mm mount, you are running a bigger adapter and presumably putting more force through that as a result.

No idea if it makes a difference or not, but if I was running a big rear disc I would be hot on checking the mount before every ride.

for me the advantage of running the big rotor up front is that it can bail you out of “ohh shit” moments.

200/203 rotors are perfectly capable of doing the job of you are riding well, but for me the 223 has saved my bacon when I have been coming into something too hot or made a mistake.

Are you riding an Aluminum or Carbon Rail?

 

[Sfs1973]

Thought I'd better add my experience. I talked to Trek UK, they said 220 rear would be 'fine' on the ally frame but not on the carbon one. Something to do with how the carbon is laid up and the amount of braking torque on the upper bolt. The guy I spoke to was actually really helpful.

Well, I went ahead and put on the MT7s 220 front and back. I guess the frame will let me know one way or another.

 

[Stihldog]

Update; regarding crack in rear triangle.
Trek replaced the lower rear triangle on my neighbours 9.7 after I installed the Mt7’s f/r 220mm rotors. I don’t think this is a common issue with the 220mm rotors. More of a riding style issue.
Regardless, Trek graciously replaced the cracked rear triangle under warranty. The effort required on the brake levers is much easier/less. Loss of braking is no longer an issue on long descents likely because heat is dissipated faster/better. A thicker rotor is reassuring also.
Side note; Bleeding the Mt7’s is a bit of a process. The initial bleed (f/r) yields a good result if done properly. However, after a few rides, some trapped bubbles are dislodged and rise to the master cylinder (lever). The brakes then feel spongy but are easily restored with a simple mini-bleed. The rear brake cylinder seems to accumulate more bubbles (likely because of multiple positions needed and length of line).
I don’t use the syringe method for a mini-bleed. Instead I screw in an adapter with a small funnel. Actuating the brake lever exspells any air trapped in the master cylinder. This is probably the last time you’ll have to bleed these brakes for several hundred Km/Miles but it’s good to check once in a while.

Some of you may use a different method or already know this stuff, but these are my experiences after installing several Mt7’s. (I’m not a LBS btw, only a neighbour with some tools).