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PostPosted: Tue Aug 30, 2011 11:47 am 
Retro Guru

Joined: Mon Jun 02, 2008 2:52 pm
Posts: 347
Ok so this is now done, it didn't turn out quite as I had hoped but its pretty cool :)

I used an SRAM X9 gripshift fitted upside down so to speak on the left bar side and a Suntour (urgh) trigger shifter next to it for the front three. The Suntour was the only one I could find that had both trigger levers in a 'push' configuration from the front; no need to pull the rear lever. This meant it would fit and work alongside the bulbous nature of the gripshift.

I made it harder by using a Hope brake lever which took up a lot of room. I had to grind/slim the cable adjuster on the Gripshift and take a little off the 'paddle' on the Suntour shifter so it would pass under the gripshift.

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PostPosted: Tue Aug 30, 2011 12:30 pm 
Gold Trader / rb Rider / Special
Gold Trader / rb Rider / Special
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Joined: Mon Aug 31, 2009 12:26 am
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Location: Rurally close.
Top work

If by both levers being pushed you mean all thumb? Some Sram shifters are thumb thumb if you were looking to upgrade.

Nice bike too!

Does the reverse grip shift make it like rapid rise?


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PostPosted: Wed Aug 31, 2011 10:46 am 
Old School Grand Master

Joined: Sun Jun 27, 2010 9:37 am
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nicely done sir :D


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PostPosted: Wed Aug 31, 2011 12:26 pm 
retrobike rider / Gold Trader
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Joined: Sun Jun 06, 2010 4:21 pm
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Location: Gateway to the Lake District
One of the posts made by the infamous 'Srands' had a link to a Tricycle disc brake that operated two calipers from one lever (designed to operate on both rear wheels).

http://www.pedicabshop.com/shop/spare-p ... rakes.html

Maybe with a bit of tinkering it could be fettled for F&R use and avoid any over the handlebar shenanigans with twin pot Hopes?! :shock: :wink:


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PostPosted: Wed Aug 31, 2011 12:59 pm 
Dirt Disciple
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Joined: Sat Mar 26, 2011 3:32 pm
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Location: Oxford
I had a friend who was born with one arm. He used to race with the same setup as that. Good work :)


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PostPosted: Wed Aug 31, 2011 1:49 pm 
Retro Guru

Joined: Mon Jun 02, 2008 2:52 pm
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Thanks :D

The brake looks crazy but the Hopes are a disappointment in terms over over the bars stopping power, rather it has a beautiful progressive feel thats super easy to modulate so the risk is minimal. We did debate a rear setup but he doesn't go offroad enough to warrant the work. We tried different forks at first (shorter) but it messed up the geometry so it has 5" Marz Air forks with a lot of air in them now, its quite hard to get the rear off the ground unless you shift weight.

The shifter is working in reverse but the mech is working as normal, the thing is as a two armed guy it takes me enough time to get used to having it all over the left anyway so any issue with the shift twisting the 'wrong' way is lost :o

I will look into the Sram triggers, it was so hard to see from photos how some stuff worked and I'd bought so many crap parts that I had to flog on/return I didn't want an expensive shifter that didn't fit.

I got the wrong frame, I'm out of the loop and didn't realise a jump frame weighed so much (duh). Its a beastly 5 n bit pounds but over all the bike is just under 28lbs. Considering he was riding something from Halfords at more like 38lbs he is happy now :O


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PostPosted: Mon Sep 05, 2011 4:17 pm 
Old School Grand Master
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Magsy wrote:
Thanks :D

The shifter is working in reverse but the mech is working as normal, the thing is as a two armed guy it takes me enough time to get used to having it all over the left anyway so any issue with the shift twisting the 'wrong' way is lost :o



You can get XTR rapid rise rear mechs if you want the numbers in the SRAM shifter match the gear or work in the correct way.

I have wonders about have a T-piece so that front and rear brakes can be operated by one lever - the callper piston sizes would need to be selected in such a way that the main braking is done by the front wheel; am sure it is doable but would need a fair amount of trial and error to get the pstons of the right size and then a brake lever so that it does not have excessive travel.

Oh, and good job BTW, 8)


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PostPosted: Mon Sep 05, 2011 5:14 pm 
Gold Trader / rb Rider / Special
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Joined: Mon Aug 31, 2009 12:26 am
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02gf74, it has been done!

http://www.bikeradar.com/news/article/eurobike-2010-trickstuff-cyclo-cross-disc-brake-converter-27723/
Although im not sure if that just converts it to cable (but that would be easier though)
http://www.cxmagazine.com/summit-labs-harnesses-the-power-of-hydraulic-disc-brakes-for-cyclocross-with-the-324-brake-adaptor

http://www.pinkbike.com/photo/7075637/
http://www.pinkbike.com/photo/6384073/

Getting varying powers from different pistons could just mean using different calipers. Single pot on rear and 2pot on the front or whatever.


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PostPosted: Mon Sep 05, 2011 6:13 pm 
retrobike rider / Gold Trader
retrobike rider / Gold Trader

Joined: Mon Oct 15, 2007 9:05 pm
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You could use the guts from two hope levers and get a local machine shop to mill you a new lever body. Run two master cylinder bores side by side with a push rod and pivot pushing on both pistons. You can then run a threaded screw down the centre of the pivot bar which will change the pivot point anabling you to tweek front to rear bias. Whilst you are at it get them to machine a perch on the new master cylinder body to take a Dura Ace bar end shifter, fitted on the left and inverted it will give you 9 speeds. Fit a single 34T ring up front and a 12/34 at the back and you will have all the gears you need.

Sounds complicated, but it'll be easy to design and build and shouldn't cost much either.

Si


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PostPosted: Mon Sep 05, 2011 7:02 pm 
Gold Trader / rb Rider / Special
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Or just get a dual/split banjo. Hydraulics see 8)


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