Just upgraded mechanical brakes to full hydraulics on my new giant defy. Is changing the rotors good or bad idea?

The rotors are only a chunk of aluminium. The power comes from the pistons and the pads. Heat build up is another matter.

I changed the trp Spyres on my Defy for shimano hydros and left the trp rotors on. No problems. I can’t imagine there’s anywhere in the UK with a long enough Road descent with enough braking for heat build up to be an issue. I’m darn sarf though so could be wrong

I changed mine from 160mm TRP to 140mm Shimano Freeza on my Defy – prettier aren’t they 😆

Dirty rider

How do you determine the rotor size? I thought I would have to stay at what bike came with.

How do you determine the rotor size? I thought I would have to stay at what bike came with.

You can use bigger rotors with adapters for the mounts

How do you determine the rotor size? I thought I would have to stay at what bike came with.

the defys all use the same frame (apart from the ones with the ISP)

the TRP brakes come with +20mm post mount adapters, the frame takes 140mm rotors stock (as seen on some of the other models) i went down to 140mm when i changed wheels as i didnt see the need for 160mm ones

Thanks dirtyrider I mite do the same. I think 160 mite be a bit too much.

They really aren’t too much. But if you want to save a few grams and have a nicer looking rotor crack on

Not if you’re 100kg !

the top spec defys come with 140mm rotors, i guess it was cheaper to spec 160mm on the lower end models

So if I take off the spacers I can have 140’s ?

Yes

160 won’t be too much. You just adjust how much you yank* on the lever. *More like gentle feathering 😉

Can’t say I’ve checked but isn’t it more likely to do with frame size? Mine is an XL. Can’t see how a bigger rotor with an extra adaptor is going to work out cheaper

The adaptor is already on the caliper. You just take it off which brings it in 20mm

Dirty rider
What do I need to do to be able to have centrelock discs. You can’t get 6 bolt on a 140mm.

ice tech rotors are just a steel-aluminium-steel sandwich to provide greater cooling when being used heavily (eg decending the Alps on a heavy full susser).

On a road bike, unless you are a big lad doing lots of downhill braking, I would have thought they were a waste of money.

Size, pad material and brake design will have more effect.

Centrelock disks need a centrelock hub so I would forget it. You can get 6 bolt adapters for centrelock hubs but not the other way round.

As for rotor size your frame and fork will have a size limit due to the forces.

Bigger rotors will also help with heat dissipation (as more area) as well as better braking.

I replaced the worm out TRP rotors on my CX bike a couple of weeks ago, I nearly went for the Icetech rotor but in the end went for the normal Shimano 6 bolt RT76’s and saved myself 8 quid an end.
I’m using RS685 hydraulics and I haven’t noticed any difference in the braking.

centrelock discs. You can’t get 6 bolt on a 140mm.

Bought centre lock wheels

FWIW I have the 140’s as standard on mine (Advanced Pro 2) and they are plenty powerful. 75kg rider. I have 160’s on my Croix De Fer and they feel just the same, although that is a heavier bike and sometimes loaded up for touring.

Sure you can’t get 6 bolt 140’s?

Google is indeed your friend…

Got a 6 bolt 140 on the back of my cotic x

Rocketdog send me a link please?

ice tech rotors are just a steel-aluminium-steel sandwich to provide greater cooling when being used heavily (eg decending the Alps on a heavy full susser).

On a road bike, unless you are a big lad doing lots of downhill braking, I would have thought they were a waste of money.

The difference between “decending the Alps on a heavy full susser” and a road bike, is the FS bikes loses a lot of energy to the ground/shock. On the road you have none of that, so the brakes do a lot more work. Also the speeds are generally higher, even on a DH track most people probably average 20mph though anything technical (where you’d need to be braking), on a road bike any chimp can hit 40mph downhill without breaking a sweat.

Not saying you need 203mm rotors, but bigger rotors, or rotors with more cooling capacity do have their place on the road. Similarly I’d not run ice-tech rotors on the commute or cross bike, the braking surface is way too thin to be durable in crappy conditions.

I can’t imagine there’s anywhere in the UK with a long enough Road descent with enough braking for heat build up to be an issue. I’m darn sarf though so could be wrong

I know of several descents on Exmoor and the Quantocks steep enough to turn my rotors blue. 😕

Derbyshire, North Yorkshire, The Peak District, Lake District and so on. Plenty of places where you can get some serious descending in.

Whats worse is a lot of them are relatively tight, twisty and steep with quite often poor surfaces. So lot of changes in speed. Some of the ones i’ve done are basically 4 or 5 minutes of repeated acceleration to 50 or 60 kph then braking to 20 or 30. Can get rims too hot to touch with no issues at all.

I’d prefer 100+kph down an alp than some of the descents in the UK.

I’ve passed 60mph (100kph) here quite a few times. 😉
Crowcombe Combe.

Anyone with links for 140mm rotors?

Anyone with links for 140mm rotors?

You can’t get Ice Tech Freeza rotors in 140mm 6 bolt.

ghostlymachine – Member

Whats worse is a lot of them are relatively tight, twisty and steep with quite often poor surfaces. So lot of changes in speed. Some of the ones i’ve done are basically 4 or 5 minutes of repeated acceleration to 50 or 60 kph then braking to 20 or 30. Can get rims too hot to touch with no issues at all.

As I understand it, this is the sort of braking you want. High speed with a occasional strong braking effort, rather than continuous dragging of the brakes, which doesn’t allow the brakes any chance to cool down in between efforts.

jacob46 – Member

Dirty rider
What do I need to do to be able to have centrelock discs. You can’t get 6 bolt on a 140mm.

Plenty of 140mm rotors available with 6 bolts….

http://www.wiggle.co.uk/sram-centerline-disc-rotor/?lang=en&curr=GBP&dest=1&sku=5360664578&ci_src=18615224&ci_sku=5360664578uk&utm_source=google&utm_term&utm_campaign=UK_PLA_Components&utm_medium=base&utm_content=mkwid%7cswCRcF2M4_dc%7cpcrid%7c67090789262%7cpkw%7c%7cpmt%7c%7cprd%7c5360664578uk

http://www.wiggle.co.uk/tektro-lyra-140mm-disc-brake-rotor/?lang=en&curr=GBP&dest=1&sku=5360493419&ci_src=18615224&ci_sku=5360493419uk&utm_source=google&utm_term&utm_campaign=UK_PLA_Components&utm_medium=base&utm_content=mkwid%7csQLRujXFy_dc%7cpcrid%7c67090789502%7cpkw%7c%7cpmt%7c%7cprd%7c5360493419uk

https://www.cyclestore.co.uk/aztec_stainless_steel_fixed_disc_rotor_140_mm-ID_55529?gclid=CMO9ueyGxcsCFesW0wodB1sFSg&gclsrc=aw.ds

http://www.winstanleysbikes.co.uk/product/64804/Avid_HS1_HeatShedding_Disc_Brake_Rotor_AV175080?gclid=CN7Y7fKGxcsCFTMo0wodi6sGQA

http://www.ebay.co.uk/itm/like/400249907070?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=122&chn=ps&googleloc=1007143&poi=&campaignid=207297426&device=c&adgroupid=13585920426&rlsatarget=pla-131843277906&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0-L&ff12=67&ff13=80&ff14=122&ul_noapp=true

http://www.ebay.co.uk/itm/Alligator-Windcutter-BLACK-Disc-Brake-Rotor-140mm-Light-62g-CX-MTB-Road-bolt/151854192215?_trksid=p2141725.c100338.m3726&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20150313114020%26meid%3Dcbf1d6d0ab9e4a0f9378b565e9d67ea0%26pid%3D100338%26rk%3D15%26rkt%3D17%26sd%3D400249907070

6 bolt not Centre locking
I ain’t changing wheels as well.

Thanks.

Have you clicked on any of those links stumpy01 posted? People try to help……

jacob46 – Member

6 bolt not Centre locking
I ain’t changing wheels as well.

Did you look at any of those links? They are all 6 bolt. 😆

davosaurusrex – Member

People try to help……

Oooooh, you wonder why you bother sometimes, don’t you!? 🙄 😀

Oooooh, you wonder why you bother sometimes, don’t you!?

Got form for it, do you have a head office he can complain to? Await the “no one answers my questions about 140mm rotors thred”. 😉

http://singletrackworld.com/forum/topic/pinnacle-arkose-4-front-hub-bearings-help-please

As I understand it, this is the sort of braking you want. High speed with a occasional strong braking effort, rather than continuous dragging of the brakes, which doesn’t allow the brakes any chance to cool down in between efforts.

It’s not occasional, it’s repeated, hard on the brakes, off for 30 seconds, hard on the brakes and so on. It’s not as bad as dragging them (is anything?), but the long open descents in the Alps and the Pyrennes might give you minutes between applications, plus it’s quite often just to feather off a bit of speed. Not dumping half of it.

I’m surprised they aren’t looking at bigger discs on road bikes to give a bigger heatsink TBH.

I’m surprised they aren’t looking at bigger discs on road bikes to give a bigger heatsink TBH.

That’s what the ice-tech/freeza rotors give you, the disk is extended inwards from the aluminium core (aluminium conducts much better than steel) to the cooling fins which give you the area (and turbulent air) which is what gives you the heat transfer.

My Ice tech ones on the MTB do stay noticeably cooler than the equivalent solid rotors.

To be fair to the OP the title does say Shimano Ice Tech 6 bolt, which I’ve not been able to find in 140mm flavour.

Ah, gotcha. Will go and have a look at that then.

OTOH, if you get them hot enough, the aluminium melts and dribbles out the bottom. Probably fine unless you’re a dragger, but lots of people are.