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PostPosted: Fri Oct 04, 2013 9:45 am 
Retro Guru

Joined: Mon Oct 05, 2009 10:58 am
Posts: 377
Location: Esix
After many many seasons of racing my 97 hei hei with orig 96/97 m952 xtr 2 things have become very apparent, (1) my bike needs to be a whole lot lighter and (2) I cant replace the parts that have come to the end of their working life (but given that most of it was bough 16 years ago I cant compalin!)

However the rear disc brake, or rather lack of fixings for it, is becoming a problem.

After all these years has anyone come up with a secure, light, safe answer to putting a modern (ie 2014 XTR) disc brake on a retro frame. My concerns being the chainstay not being strong enough to cope and not being able to release the back wheel without a lot of faffing when I puncture in a race.

Comments / suggestions welcome please....

Oh and on an aside anyone who says retro bikes dont cut it with the modern stuff - this bike (with original 96 crossmax wheels) came second overall in the vets category at this whipstakes races in kent (against the usual aray of 29ers and 650b) - :D


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PostPosted: Fri Oct 04, 2013 9:54 am 
King of the Skip Monkeys
King of the Skip Monkeys
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Joined: Wed Nov 07, 2007 4:34 pm
Posts: 26154
Location: Moomin Valley
I used to use something like this on my Zaskar around 1998, maybe earlier as I had a Hope disc on the front.

Image

Current version:

Image


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PostPosted: Fri Oct 04, 2013 10:03 am 
Retro Guru

Joined: Mon Oct 05, 2009 10:58 am
Posts: 377
Location: Esix
Ive seen that 2nd one and looks quite neat but wont be able to get my back wheel out in a hurry without 'modification'

I love the first one but dont think I can fit modern calipers to it - looks quite light too....


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PostPosted: Fri Oct 04, 2013 10:05 am 
King of the Skip Monkeys
King of the Skip Monkeys
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Joined: Wed Nov 07, 2007 4:34 pm
Posts: 26154
Location: Moomin Valley
modern calipers would go straight on with all the adapters that are available. I ran a Hope on the rear for about five minutes before sacking the whole thing off and went over to a Marin Mt Vision instead...


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PostPosted: Fri Oct 04, 2013 10:12 am 
Devout Dirtbag
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Joined: Fri Sep 10, 2010 12:28 pm
Posts: 149
Location: Basque Country
Front brake is responsible of most of the braking power on a bike, knowing this, why not just use a front disk brake on the fork and a rear V Brake?


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PostPosted: Fri Oct 04, 2013 10:21 am 
Retro Guru

Joined: Mon Oct 05, 2009 10:58 am
Posts: 377
Location: Esix
i did consider staying with v fullstop but then found there was no such thing as a sub 1400 rim brake whell that would accept 10 or 11 speed..


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PostPosted: Fri Oct 04, 2013 10:31 am 
Gold Trader
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Joined: Fri Jan 23, 2009 2:30 pm
Posts: 12407
Location: Surrey
bigdawg wrote:
i did consider staying with v fullstop but then found there was no such thing as a sub 1400 rim brake whell that would accept 10 or 11 speed..

I'm surprised you can't get a light rim brake wheel, as th hub doesn't need any additional material to fit the rotor, saving weight there. Isn't it also as false economy comparing wheels as you will also need to count the rotor in any calculations. I'd imagine that the overall overall disc brake system is also heavier than a v brake set up, so even if the wheels are slightly more portly, wouldn't the overall weight if these system be less?

No idea myself, just a brain dump.


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PostPosted: Fri Oct 04, 2013 10:42 am 
Retro Guru

Joined: Mon Oct 05, 2009 10:58 am
Posts: 377
Location: Esix
a year ago you would have been right but the new XTR has set a new benchmark with weights now slashed to that of near M952 v brakes

the other thing I noticed (with my racers head on) was that as you pointed out the weight is centered aroundthe hub whereas with rim brakes the there is ibviously extra weight at the rim as they need to be stronger which means more effort required to push it up hills - yes we are talking minimal gains and possibly seconds a climb but tbh that could make a big difference over a 2 hour plus xc race especially a hilly one.

Also Ive noticed a lot of the new xc courses (the olympic one esp - as its on my doorstep) depends a lot on partially applying the brakes to temper entry speed to some of the obstacles and get safely down some of the drops, with 'V's theres always been an on/off feeling to braking.

Tbh I would love to carry on racing a totally retro bike, its not a decision Ive taken lightly at all, but having to spend a month sourcing a new chainring or cassette when I ve got a race in a week or so is getting harder and more expensive.


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PostPosted: Fri Oct 04, 2013 10:47 am 
Retro Guru

Joined: Sun Aug 07, 2011 10:55 am
Posts: 2920
Location: Dorset
I have noticed recently after riding my old and new mtb's almost side by side the v brakes are either on or off like you say. The modulation of the hydraulics seem to allow me to just dad a little on the brakes, shed a tad of speed.


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PostPosted: Fri Oct 04, 2013 10:52 am 
MacRetro rider
MacRetro rider

Joined: Fri Feb 09, 2007 4:16 pm
Posts: 8658
Mavic Crossride UB rear rim brake wheel is 1040g which seems pretty light plus wouldn't a Magura hydraulic rim brake give you plenty modulation and still be retro ?


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