David Posted October 31, 2017 Report Share Posted October 31, 2017 Hi all, Potentially looking to change the discs on my Czar Ion 24" to 203mm rotors. They come with 180mm as standard and both are IS. Do I simply need the front and rear "203mm" Shimano adaptors? http://www.chainreactioncycles.com/mobile/shimano-mount-adaptor-front-post-to-is/rp-prod13743?gs=1&utm_source=google&utm_term=&utm_campaign=Chain+Reaction-UK-PLA-PLA-All-MB-SE-Shopping+QLB+Manufacturer+Mobile&utm_medium=base&utm_content=mkwid|sfn1nSdVW_dm|pcrid|161814140553|pkw||pmt||prd|38589UK Quote Link to comment Share on other sites More sharing options...
Daviesdt Posted October 31, 2017 Report Share Posted October 31, 2017 Are your brakes post mount? You don't mention. Have you checked that your forks are ok with a 203mm rotor? The large rotor increases the stress on the forks IS mounts so you need to check the max rotor size the manufacturer recommends. Quote Link to comment Share on other sites More sharing options...
David Posted October 31, 2017 Author Report Share Posted October 31, 2017 1 minute ago, Daviesdt said: Are your brakes post mount? You don't mention. Have you checked that your forks are ok with a 203mm rotor? The large rotor increases the stress on the forks IS mounts so you need to check the max rotor size the manufacturer recommends. Brakes are both post mount. Warranty only covers up to 180mm which seems fairly standard but I'm willing to take that risk. 1 Quote Link to comment Share on other sites More sharing options...
Daviesdt Posted October 31, 2017 Report Share Posted October 31, 2017 Ha! Go for it then. Dude, those Shimano brackets will do the job. Quote Link to comment Share on other sites More sharing options...
Mark W Posted November 2, 2017 Report Share Posted November 2, 2017 If you've got BB5s (which I think the Ion has from standard?), then before going to bigger rotors it might be worth giving the Trialtech Sport Disc Brake Pads a try. I've used them on my Hope and my Magura brakes and the difference in braking power from normal pads is pretty amazing! Quote Link to comment Share on other sites More sharing options...
monkeyseemonkeydo Posted November 2, 2017 Report Share Posted November 2, 2017 +1 for@Mark WÂ there. I actually went down from a 180mm rotor to a 160mm on the back of my Arcade when I changed to Trialtech pads on my Hopes. Quote Link to comment Share on other sites More sharing options...
David Posted November 5, 2017 Author Report Share Posted November 5, 2017 On 11/2/2017 at 9:40 AM, Mark W said: If you've got BB5s (which I think the Ion has from standard?), then before going to bigger rotors it might be worth giving the Trialtech Sport Disc Brake Pads a try. I've used them on my Hope and my Magura brakes and the difference in braking power from normal pads is pretty amazing! Hi Mark, Yes BB5 on the front (which works well to be honest) but I've upgraded to an old Saint M810 on the rear. However, the brake just isn't performing well at all. It's brand new (I got very lucky on Ebay!) with sintered pads and I've given it a fresh bleed. If I wet the rotor it works amazingly but progressively gets worse after a short time. I've had quite a lot of rides on it now and followed all the normal bedding procedures so something isn't right. I thought starting again with a new rotor and pads might help things but maybe I am going over the top?! Quote Link to comment Share on other sites More sharing options...
Mark W Posted November 5, 2017 Report Share Posted November 5, 2017 Nah, that sounds like you've got either a contaminated rotor or contaminated pads (from your "Good when wet, then gets worse" comment), so switching both out would be a good call. Just as a random other point of order, don't use disc brake cleaner on them Quote Link to comment Share on other sites More sharing options...
David Posted November 5, 2017 Author Report Share Posted November 5, 2017 34 minutes ago, Mark W said: Nah, that sounds like you've got either a contaminated rotor or contaminated pads (from your "Good when wet, then gets worse" comment), so switching both out would be a good call. Just as a random other point of order, don't use disc brake cleaner on them I suspect it is contamination. Oh, what's wrong with disc brake cleaner? Quote Link to comment Share on other sites More sharing options...
Mark W Posted November 5, 2017 Report Share Posted November 5, 2017 They just seem to leave a residue that doesn't really help things. Mountain bikes or motorbikes go fast enough that the brakes generate heat to burn it off, but trials bikes don't so it seems to be unhelpful overall. Quote Link to comment Share on other sites More sharing options...
Mikee Posted November 5, 2017 Report Share Posted November 5, 2017 What brake cleaner are you using? I've never had any "residue" problems. Quote Link to comment Share on other sites More sharing options...
monkeyseemonkeydo Posted November 6, 2017 Report Share Posted November 6, 2017 Brake cleaner + a lighter is always good for a laugh. If I've had contaminated rotors a good douse of cleaner and set it alight... do it outside of course Quote Link to comment Share on other sites More sharing options...
Scott B Posted November 6, 2017 Report Share Posted November 6, 2017 I've had good luck with taking a micro torch to the disc and pads to burn off any crap. Quote Link to comment Share on other sites More sharing options...
David Posted November 8, 2017 Author Report Share Posted November 8, 2017 So the new rotors and adaptors arrived today. The front works fine but the rear caliper sits too high on the rotor  The adaptor appears to bring the caliper more towards the front of the bike than the previous one. I've attached a photo of the rear adaptor I purchased. Any ideas?    Quote Link to comment Share on other sites More sharing options...
David Posted November 8, 2017 Author Report Share Posted November 8, 2017 (edited) Hmm, it looks as if the equivalent shimano adaptor in 180mm might do the trick... Edit: On second thoughts I noticed the original Avid mounts appeared to both be identical. Does this mean maybe the Front 203mm Shimano mount will work on the rear? Edited November 8, 2017 by David Quote Link to comment Share on other sites More sharing options...
David Posted November 8, 2017 Author Report Share Posted November 8, 2017 Update: Mystery solved! (or more mystery uncovered). Out of curiosity I took my new Shimano front adaptor and tried it on the rear...a perfect fit! So looks as if you require two FRONT shimano 203mm adaptors to run 203 rotors. Quote Link to comment Share on other sites More sharing options...
richard0800 Posted November 23, 2023 Report Share Posted November 23, 2023 I asked the manufacturer, they said rear mount needs to run a size smaller, so 180mm rotor needs 160mm adapter. (yeah, it's an old topic, but i think this might help others) Quote Link to comment Share on other sites More sharing options...
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