I’ve fitted a set of Rx4 calipers to my Planet X Tempest, and noticed the flat mount holes at the rear don’t quite allow for central positioning of the caliper (ie the slot the bolt goes through doesn’t allow the bolt to get close enough to the chainstay,it’s further toward the hub)

Was wondering if it was worth attempting to file it a bit to allow more accurate positioning. At the moment it’s causing the rotor to flex a bit but it’s not terrible…and I’m not sure how easy filing titanium is!

Anyone done similar? Did they die?

Bump – forum borked?

Titanium is no more difficult to file than stainless steel. As long as it is a sharp new file.

I remember planet x selling discounted frames where they actually said how to file the mount down to make the caliper fit 🤣 but that was a log time ago.

Before you touch the frame and cancel your warranty I would take some photos and email planet x and ask them for advice or perhaps a repair or replacement.

How old is it?

What have you removed and did the previous set have this same issue? Sure it’s the frame and not the caliper?

Piece of piss just keep the file clean.

As the man said, no worse than stainless. Just work deliberately and clean your tools between cuts.

Is it the frame or the hub?

You can have 6 bolt hubs faced can you not?  Not sure about centrelock. If possible I’d rather face a hub than file a frame.

Also is the hub sitting centrally? If it’s a Tempest, have you got Fulcrum wheels and are the 12mm caps properly fitted and screwed in.  If they’re a bit off then that could be the problem.  I know my ones like to unscrew occasionally (might be one side only, but worth checking before any filing or facing)

Thanks – it was a bit off with the Shimano’s as well, but it never bothered me…I only started thinking about it because the Hope instructions made such a big point about it being central (reduced clearance, I guess, so it affects it more?)

Definitely some food for thought – I hadn’t even considered the hubs; I’m using Hunt’s rather than the fulcrums it came with, but I’ll give them a check. Frame is a couple of years old so (just) out of warranty, but definitely a good call to ask if they have any advice.

Typical Planet X/on one quality!

Easy check with the hubs is borrow some wheels. Mates or bike shops ought to help if you don’t have a spare set.

Not sure if I’m reading your post correctly but sounds more like you need to shim the rotor to bring it out slightly? Same as fileing the inside of the frame to bring the caliper inboard.

Hope used to make them, I’ve got a few in the shed from the days when IS mounts were more of a suggestion than a standard 🤣

Thanks…think it’s more the other way around, though (ie rotor needs to be further away from caliper rather than closer).Will experiment with some different wheels this weekend!

Just an update on this in case anyone’s interested, or has similar issues.

Tried with a couple of wheels, and remounted the old caliper to check – the rear disk flatmount is definitely misaligned.

I noticed a couple of other older forum posts with people having the same issue, so this does seem to be Planet X “quirk”. I did reach out to them (was still just within warranty), and they were supremely uninterested. Didn’t push it as I can’t really stand the thought of being without my bike for however long it would take to post and sort out anyway

Current plan is to add a washer to the non drive side of the hub to push the chainstay out just a little (1mm)…hoping this won’t have a noticable effect on ride/balance?

A few tips when filing titanium, use a file that’s new or only been used for titanium, make sure it’s fine, grinding stones work well, little oil applied as well is always good. Don’t use power tools either.

Probably overkill, but these were the basics when rectifying titanium parts on aircraft back in my A/C tech days, worst job ever was rectifying massive titanium parts!

Personally I’d be pushing planet x to sort it. Good luck.

Sorry, misread the OP.

Could you put a round file in a drip and use that?

Hi all…just wanted to update on this with a thanks for all the suggestions, and a shoutout to Planet X; I took the advice here and followed it up with them, and they’ve been brilliant to be honest – problem sorted.

Well come on … what did they do to sort it? 🤷‍♂️

He sent it them back, they used a file and sent it him back fixed?

I’d have been happy with that! They replaced the frame in the end (including a new seatpost and collar as the v4 is a different size).

Years ago there used to be a px/oo bashing thread nearly every week. But there hasn’t been one for a while.

I think the last one @brant paid some money out from his own pocket for something that happened years before.

In fact there’s been a lot of love for them. They seem to be one of the only bike shops that have been able to keep up with demand.

Maybe the new Co op ownership is working well.