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 Post subject: XT Freestroke
PostPosted: Sat Sep 22, 2012 3:49 pm 
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Posts: 311
Location: Chelmsford
Hi All,

I'm hoping to get out and ride with some of you soon, probably on a Saturday at Epping, but work just keeps getting in the way just recently. I need to shoehorn a ride in desperately.

I was hoping someone may be able to offer some advice on the XT Freestoke adjustment, as to me it doesn't really seem to do a great deal. The issue with my brakes is the stroke distance on the lever before the pads engage. The pads are new, the brakes have recently been bled and everything is in good order. However, despite adjusting the leaver to the right finger distance for one-fingered braking, the stroke is so long that the lever is almost touching my grip fingers before I get any decent brake bite.

I don't want to move the lever any further away as this just causes over extension and arm pump.

Any suggestions? I just want a nice short stroke distance so I can have the lever close to the grip.

Here's a link to a .pdf mentioning free stroke:

http://techdocs.shimano.com/media/techdocs/content/cycle/SI/Deore-XT/DiskBrakeSystem/BRM775/SI-8EP0A-007-ENG_v1_m56577569830745900.pdf

Cheers.

@pples :mrgreen:

--------------------------------------
Butcher | Hanzz | SL3


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 Post subject: Re: XT Freestroke
PostPosted: Sat Sep 22, 2012 4:54 pm 
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Posts: 1335
They look similar to the Saints, its well known that the mysterious free stroke adjustment on Saints does bugger all....and Ive yet to read a good explanation as to what it does (or even what Shimano intended it to do), I believe its supposed to bring the pads nearer to the rotor but it doesn't appear to do that.

Use the reach adjustment to get the lever to the right place, if you feel there is too much travel in the lever then new pads/ a fresh bleed might help, when the system is bled I like to squeeze the levers and keep them in that position (using cable ties or something) for a few hours or overnight.

Google Saint or XT free stroke and youll find lots of other baffled users :) http://www.pinkbike.com/forum/listcomme ... did=130872

Andy


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 Post subject: Re: XT Freestroke
PostPosted: Sun Sep 23, 2012 12:12 pm 
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Posts: 311
Location: Chelmsford
Cheers Andy, I'll try this theory of moving in the piston with the rotor out. Apparently it fools the piston into being closer to the rotor. I'll also look into a bleed with the lever partly depressed to draw more fluid into the closed chamber. We'll see.

-Dave

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Butcher | Hanzz | SL3


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 Post subject: Re: XT Freestroke
PostPosted: Sun Sep 23, 2012 7:53 pm 
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Posts: 1335
As mentioned, googling it, brings up a million and one suggestions, Im about to bleed my Saints so Ill post how I get on.

Andy


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 Post subject: Re: XT Freestroke
PostPosted: Mon Sep 24, 2012 9:11 am 
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Posts: 2082
Location: Southend
How about swapping the 10mm spacer for a narrower one when bleeding ?

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It doesn't matter what you ride


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 Post subject: Re: XT Freestroke
PostPosted: Mon Sep 24, 2012 11:15 am 
Posts: 110
Location: Colchester
+1 on adnydd's comments. The freestroke on Shimano's brakes is well known for doing next to nothing!

Sounds like they might need bleeding again. If you reverse bleed them using the syringe method you can sometime squeeze a little extra oil in the system before you nip the bleed nipple up which will help.


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 Post subject: Re: XT Freestroke
PostPosted: Mon Sep 24, 2012 11:50 am 
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Posts: 311
Location: Chelmsford
Cheers, this seems like such a fundamentally basic function of a braking system, yet so much work has to go in to achieve the desired setting. hang your head in shame Shimano R&D!

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Butcher | Hanzz | SL3


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 Post subject: Re: XT Freestroke
PostPosted: Mon Sep 24, 2012 12:13 pm 
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Posts: 2082
Location: Southend
I'm not disagreeing with anyone but find this hard to get my head around seeing as i've spent the last 19yrs perfecting hydraulic applications.

if the system is full of good condition fluid there is nowhere for extended movement of any part unless it is engineered into the system.
only contaminants (water or degraded hydro oil) or air ingress will allow for any extra compression resulting in extra movement of the lever

but.... the length of your lever directly affects the amount of pressure you can exert, perhaps a thicker oil would give you the feel and resistance you need, shimano hydraulic oil is incredibly thin, there are loads of different viscocities you can use, just make sure its mineral and not fully synthetic as it will eat away the small seals in the system

better add that the lower the viscoity the higher flow rate (but not the volume) which will mean quicker acting, before you pour higher viscocity oil into your system beware that your brakes will start to feel sluggish in comparison to the lower rated oil.

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It doesn't matter what you ride


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 Post subject: Re: XT Freestroke
PostPosted: Mon Sep 24, 2012 12:34 pm 
Posts: 110
Location: Colchester
I totally agree. In the majority of cases the issue is usually air in the system somewhere, especially if the lever is hitting the bar. Sometimes its just very hard to get out without a judicious amount of tapping and fettling. Even good mechanics will swear all the air has been bled, only to find there is a bit lurking in some dark corner of a calliper!

As for the freestroke adjustment I've never seen much point in it. Most of them (with the exception of Hopes for some reason) does very little and is just something else to go wrong. I picked new SLX brakes over the XT ones mainly because they didn't have it!

I've not much experience of hydraulics beyond mtb brakes and forks, although I know viscosity makes a massive difference in forks. I'd guess the shimano oil is so thin because the ports and hoses are really only a 1mm or so diameter and thicker oil would probably slow the lever return??


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 Post subject: Re: XT Freestroke
PostPosted: Mon Sep 24, 2012 6:20 pm 
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Posts: 1335
Last year in Morzine, one guy had some Hopes and the Free Stroke (or whatever Hope call it) adjuster did indeed appear to have quite an effect.

Id be interested to know what the Shimano one does, does the screw potrude slighly into the resevouir and when tighten in, reduce the volume(slightly !) and thuis push the pads out ?

Having said all that, Im very pleased with my Saints and they can have awesome stopping power.

Andy


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