Exceeding max fork rotor size by 10mm = certain death?

Now then…

After much investigation I have found the adaptor I need to get my old school Hope M4’s (IS) to fit my RS lyriks (Post). However, as the caliper was originally designed for 200mm rotors it seems I will need to go up to 220mm rotors.

RS state that max rotor size for fork is 210mm….

Does anyone know what the risk is here? Is it cracking lowers? I guess the warranty on my forks is up as they were 2nd hand and are now old so not worried about this..

Any advice would be greatly appreciated.
Ta

Yes you will die, there is a zero plus IS to Post mount out there though

Seriously probably not

Almost as bad as jetwashing your bike. So you will probably only be wounded, badly in the goolies.

Max rotor size recommendations are an odd one.

A smattering of physics will tell you that the larger the rotor, the smaller the force on the mounting bolts etc. The ultimate big rotor, of course, is a rim brake.

So why do forks have max sizes? I think it’s more to do with the kind of person who wants to run big rotors, and whether they’re more likely to do big jumps on XC forks. It’s a subtle way of saying “this is an XC fork, don’t be daft” 🙂

A smattering of physics will tell you that the larger the rotor, the larger the force smaller the force on the mounting bolts etc.

For the same stopping power a bigger rotor needs less force from the pads. But you’ve put it on a biger lever (the addapter) so the force on the bolts is about the same (probably bigger on one, smaller on the other as your mounting the calliper further from the center of the 2 bolts). However bigger disks give more stopping power as at the end of the day you’re going to pull the lever as hard as you can and the ‘lever’ is now bigger = more force.

10mm probably wont kill you though.

That’s kinda what I was getting at – larger rotors encourage more extreme behaviour which generates higher forces 🙂

I feel better about this 10mm now.. Thanks!

Mike – do you have any more detail on this zero plus IS to Post mount adaptor please? Can’t find much online and if there is one out there it will save me £30 on a big rotor.

Cheers

Link HereWas on an old post

I had a pair of pace triple clams fail due to too large a disc, carbon on te back of the leg folded, luckily while riding around a car park!

Conan – how much did you exceed the maximum by? Do you think it was the carbon that played a part in it?

Getting a little worried about this 10mm again…

Cheers