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PostPosted: Sat Sep 21, 2013 3:09 pm 
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Joined: Tue Sep 21, 2010 8:08 pm
Posts: 1939
Location: East Lothian
I recently acquired a 185mm Hope 5 bolt disc and spider to fit my old hope bulbs.

I want to fit them on to Marzocchi Forks and use Magura post mount disc brakes. When I previously used this combination with a Magura 180mm Disc, I used a 160mm IS to Post adapter which gave a perfect fit.

However the Hope disc is just too big - but not by much.

Can I space out the adapter with a couple of washers as shims between the adapter and caliper and use longer bolts to compensate?


Many thanks


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PostPosted: Sat Sep 21, 2013 7:25 pm 
MacRetro rider
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Joined: Thu Jul 30, 2009 4:56 pm
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Location: A Fifer furth o' the Kingdom
I would do that no problem. Depending how many washers you have to use, the original bolts might be long enough.

Seem to remember having a problem with a Hope 5-bolt disc and a non Hope IS caliper, so couldn't space it, with the edge of disc touching inside of caliper. Solved it with an angle grinder :shock: , by putting wheel and disc in fork, then using sanding-disc against edge of disc. As disc/wheel was spun by the angle grinder, the sanding disc gently and evenly reduced the diameter of disc enough to fit in caliper.
I've no idea why Hope made discs with diameters of 185mm and 203mm when everybody else used 180 and 200 discs.


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PostPosted: Sat Sep 21, 2013 10:46 pm 
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Thank you - I was all set to do that at first but the outer line of drill holes is very close to the edge...


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PostPosted: Sat Sep 21, 2013 11:14 pm 
Gold Trader / MacRetro rider
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Joined: Sun May 25, 2008 11:03 am
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Location: Sunny Glasgow
Yes indeed. the bolts should be fine. By how much are we talking ? 3mm :?

The extra couple of mil would no doubt translate into some advertising blurb about 5% more power over the competitors rotors. Or something such.


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PostPosted: Sun Sep 22, 2013 8:41 am 
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Using primary school maths, we're talking about 2.5mm of washers as spacers.
I can't see any negative issues with doing it


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PostPosted: Sun Sep 22, 2013 9:39 am 
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Location: Berks
203mm is almost spot on 8". 185mm is more or less 7.25". Should have gone for 184mm if that was the logic...


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PostPosted: Sun Sep 22, 2013 9:58 am 
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Thanks All

My bolts were all either 3 turns or so too short or too long. I went with the over long versions. I cleaned the disc with brake cleaner and refaced the pads with wet and dry. I just need to re-bleed the brakes.


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PostPosted: Sun Sep 22, 2013 12:29 pm 
Gold Trader / MacRetro rider
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Location: Sunny Glasgow
Bullpup wrote:
Thanks All

My bolts were all either 3 turns or so too short or too long. I went with the over long versions. I cleaned the disc with brake cleaner and refaced the pads with wet and dry. I just need to re-bleed the brakes.



I also use a blowlamp(the kitchen type is best as it isnt too harsh) and then face the pads with 1000 W&D stuck onto a small piece of glass to ensure flatness.

I really hate the way many bike shops used to insist the customer changed their pads even if it was minor contamination from a leak or bleeding spillage. Thankfully more customers are aware you dont have to.
Bit of a con and it probably hasnt done the reputation of LBS's too good, and with online sales :?


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PostPosted: Sun Sep 22, 2013 2:19 pm 
retrobike rider
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Joined: Thu Apr 17, 2008 1:24 am
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Location: Manchester
Use decent washers, not the pressed steel ones that aren't flat.

Or use the Avid washer kit with the V-brake cup and cone washers, they should be about the right size.


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PostPosted: Sun Sep 22, 2013 2:56 pm 
MacRetro rider
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Joined: Thu Jul 30, 2009 4:56 pm
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Location: A Fifer furth o' the Kingdom
dyna-ti wrote:
Bullpup wrote:
Thanks All

My bolts were all either 3 turns or so too short or too long. I went with the over long versions. I cleaned the disc with brake cleaner and refaced the pads with wet and dry. I just need to re-bleed the brakes.



I also use a blowlamp(the kitchen type is best as it isnt too harsh) and then face the pads with 1000 W&D stuck onto a small piece of glass to ensure flatness.

I really hate the way many bike shops used to insist the customer changed their pads even if it was minor contamination from a leak or bleeding spillage. Thankfully more customers are aware you dont have to.
Bit of a con and it probably hasnt done the reputation of LBS's too good, and with online sales :?


Agree with that, I just put the pads on the electric cooker at a low heat. It's flat so heats evenly and I can see brake fluid come to surface and boil off. They're designed to withstand heat but I'd not let them get so hot the metal backing changes colour. :roll: Once cool enough I rub them friction side down on flat paving slab outside. It's flat and just rough enough to clean up pad surface. I've found that the pads grip just as well as when new.


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