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HELP! I don't understand disc brakes...

secretsamsecretsam Posts: 4,864
edited September 2016 in Commuting chat
So, just pulled the trigger on a disc braked bike. Apparently, it has Centre-lock discs on it, but it's a road bike. Now I'm new to all this disc malarky (have an MTB but that's just a toy :lol: ).

As the stock wheels are likely to be a tad weighty, I may replace them and flog the originals or use them elsewhere.

Questions:
1. Can centre-lock discs be used on 6 bolt wheels? Or would I need to get new rotors for a 6-bolt wheelset
2. The bike uses standard QR as far as I can tell. AFAIK, it's 135mm spaced at the back. Could the wheels therefore be swapped onto my MTB for road use (assuming discs are same size)

This is like learning a new language. Some standardisation would be really nice, perhaps? At least I don't have to learn what the hell a "Thru-axle" is :oops:

It's just a hill. Get over it.

Posts

  • cooldadcooldad Posts: 32,601
    1 - you can get adapters the other way round, but not the way you want, I don't think. So new rotors.
    2 - Assuming they will fit. Road wheels may not fit a 26er.
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  • veronese68veronese68 Posts: 24,662 Lives Here
    1. No, I think not. I believe you can get adaptors to use 6 bolt rotors on centre lock wheels but not the other way around. Rotors aren't expensive so don't restrict yourself to centre lock wheels. I bought some 6 bolt rotors for peanuts off the Bay and keep them as spares.
    2. Possibly. Depends what size wheels your MTB is running and how much frame clearance you have. 29er MTBs have the same rim diameter as 700c road wheels so no problem. 26.5 or 650b whatever they call the middle size that is current favourite they will probably fit as road tyres are much smaller so the overall diameter should be similar. If the MTB is 26" they may fit depending on what the overall diameter is.
    Standard QR MTB spacing is 135mm at the back so that's not a problem.
  • SecretSam wrote:
    Questions:
    1. Can centre-lock discs be used on 6 bolt wheels? Or would I need to get new rotors for a 6-bolt wheelset
    2. The bike uses standard QR as far as I can tell. AFAIK, it's 135mm spaced at the back. Could the wheels therefore be swapped onto my MTB for road use (assuming discs are same size)

    1. Nope, and Shimano, in their wisdom don't make the 140mm Ice-Tech rotors that it comes with in a 6-bolt version either. This is a pain and the XT rotors are really, really good. Also be a bit careful as when I replaced the front wheel with a dynamo hub, the large flange caused the spokes to foul the caliper when using a 140mm rotor, I added a spacer to the caliper and used a 160mm rotor on the front to stop this.
    2) Yes, if you have clearance for 700c. The quick release and spacing is the same as my QR MTB. That said, the rotors will be different as mountain bikes generally have bigger rotors.
  • SecretSam wrote:
    So, just pulled the trigger on a disc braked bike. Apparently, it has Centre-lock discs on it, but it's a road bike. Now I'm new to all this disc malarky (have an MTB but that's just a toy :lol: ).

    As the stock wheels are likely to be a tad weighty, I may replace them and flog the originals or use them elsewhere.

    Questions:
    1. Can centre-lock discs be used on 6 bolt wheels? Or would I need to get new rotors for a 6-bolt wheelset
    2. The bike uses standard QR as far as I can tell. AFAIK, it's 135mm spaced at the back. Could the wheels therefore be swapped onto my MTB for road use (assuming discs are same size)

    This is like learning a new language. Some standardisation would be really nice, perhaps? At least I don't have to learn what the hell a "Thru-axle" is :oops:
    What bike and what wheels?
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  • Ah, a Pinnacle. Weight of 8.9kg.

    Now then, those might be quite ok wheels actually. These MIGHT be lighter.

    http://www.wiggle.co.uk/cosine-23mm-all ... -wheelset/

    this adaptor

    http://www.superstarcomponents.com/en/c ... oCXDDw_wcB

    but if you bought new wheels I'd just get some discs for it and have two sets of wheels
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  • secretsamsecretsam Posts: 4,864
    Ah, a Pinnacle. Weight of 8.9kg.

    Now then, those might be quite ok wheels actually. These MIGHT be lighter.

    http://www.wiggle.co.uk/cosine-23mm-all ... -wheelset/

    this adaptor

    http://www.superstarcomponents.com/en/c ... oCXDDw_wcB

    but if you bought new wheels I'd just get some discs for it and have two sets of wheels

    LOL, yes it's the great SecretSam C2W assault on Evans: a Pinnacle 5 disc, in a lovely red :D

    Funnily enough, it was checking out those Cosine wheels that made me ask the original question!!!!!! :lol:

    It's just a hill. Get over it.
  • The Cosine wheels should be a marginal upgrade. The set yours came with and the Cosines are both essentially Alex Rims builds, but the Cosines are cartridge bearings (vs the loose in yours) so potentially easier to maintain and the overall wheel will probably be a bit lighter (I found their quoted weight to be spot on). I'd just buy some new rotors like everyone's suggested - adaptors are a faff and rotors are cheap!

    I was very impressed with the Cosines for commuting - though the freehub splines are made of cheese and getting cassettes on and off was a pain after a couple of hundred miles. I only got rid of them because I sold a bike and they were the cheapest wheels I had left to pair with it. Doubt you can get much more for your money anywhere else.
  • dhopedhope Posts: 6,699
    I very nearly bought some Fulcrum 5 DB's a week ago. If PBK have the reducing discount on again then have a glance - centrelock with QR was already cheaper there than elsewhere, and with the discount would have dropped to £184 from £229

    They're on now at £206 though
    http://www.probikekit.co.uk/bicycle-whe ... 34077.html
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  • mtb-idlemtb-idle Posts: 2,179
    I think we are getting there but just for clarification, the difference between centre-lock and 6-bolt if it wasn't already obvious is the way the disc is secured to the hub.

    Centre-lock - check out the alu coloured serrated section on left hand side. This is where the disc sits

    shimano-xt-front-hub.jpg?w=430&h=430&a=7

    6 bolt system - clue is in the question, it's got six bolt holes that secure the disc to the hub

    HU8417.jpg

    So are they interchangeable? In short no although i think you can get adaptors but replacement discs are dirt cheap so just buy another set

    your wheels should be able to be swapped to your MTB. Again it depends on clearances but I have 700c wheels on a 26" steel frame and it works fine. it may just need the disc calipers on the mtb to be re-aligned as the discs are bound to be in a slightly different plane than the existing wheels.

    21-07-2012_01.jpg

    5 minute job

    Thru-axle? An axle that is a lot fatter than the 9mm QR axle you currently have e.g. the below which would probably fit through that shimano hub up there (note it has a lot larger hole for the axle than you would expect).

    2204929_1.1rlslylvso.jpg

    It needs to have a thru axle specific frame
    FCN = 4
  • dhope wrote:
    I very nearly bought some Fulcrum 5 DB's a week ago. If PBK have the reducing discount on again then have a glance - centrelock with QR was already cheaper there than elsewhere, and with the discount would have dropped to £184 from £229

    They're on now at £206 though
    http://www.probikekit.co.uk/bicycle-whe ... 34077.html

    Bloody great wheels and it should be very easy to find some "new customer" deal with PBK to get some money off.
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  • DrLexDrLex Posts: 2,142
    If it helps, there's a chap on STW who is a senior Pinnacle bod - jameso who is very helpful on the subject of his bikes - maybe drop him a short mail?
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  • secretsamsecretsam Posts: 4,864
    Thanks all for the advice!
    MTB-Idle wrote:
    21-07-2012_01.jpg

    LOL looks like it's on stilts...

    It's just a hill. Get over it.
  • mtb-idlemtb-idle Posts: 2,179
    yup, but it does the job. Here's my youngest climbing on it last year

    TDF_016.jpg
    FCN = 4
  • The RookieThe Rookie Posts: 27,748
    MTB-Idle wrote:
    It needs to have a thru axle specific frame
    Sort of, you can also get 9/10mm through axle setup which will fit in a normal 9x100/10x135 frameset.
  • secretsamsecretsam Posts: 4,864
    MTB-Idle wrote:
    yup, but it does the job. Here's my youngest climbing on it last year

    TDF_016.jpg

    That's sickening. I get out of breath just looking at that photo :lol:

    Reminds me of seeing kids romping up Bridge Valley Road before the Tour of Britain came through...4 year olds zooming up... :oops:

    It's just a hill. Get over it.
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