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ST-785 Disc brakes excessive throw distance

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ST-785 Disc brakes excessive throw distance

Old 08-06-20, 08:04 PM
  #1  
Chandne
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ST-785 Disc brakes excessive throw distance

I have Shimano ST-785 hydraulic disc brakes (Dura Ace) on my Tarmac, The throw distance seems to be very long and it gets quite close to the handlebar before engaging. No adjustment seems to fix this. The side screw does not move the pistons in as they are apparently supposed to. Is there any sort of fix for this? I guess one could overfill the system through the caliper slightly to push out the pistons but I was hoping someone had a better idea (besides replacing them) since I cannot afford a new groupset. I had a baby and the nanny take all my disposable income.
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Old 08-06-20, 08:29 PM
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dsaul
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This is for a different lever, but the procedure should be the same.
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Old 08-07-20, 06:57 AM
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Canker
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or they just need bleed
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Old 08-07-20, 07:07 AM
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On my Shimano hydro brakes, the lever travel increases as the pads wear down...So you might try new pads.

By the way, using your nanny as an excuse for not being able to afford to replace your top-of-the-line groupset will not garner you much sympathy.
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Old 08-07-20, 12:23 PM
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vane171
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If it is the same as on an automobile brakes, then it needs proper bleeding. I don't have disc brakes on my bike but I bled my brakes on my vehicle and low brake pedal means not enough fluid in the system, or it wasn't bled properly. Also hope you know such things of 101 type lesson, like that fluid in the refill bottle shouldn't be shaken up, it introduces bubbles into it...
If the pads are worn but not beyond some set limit, that shouldn't affect the brake levers travel if the brake housing fluid container holds some extra fluid, like in an automobile. If not, then you would need to top it up at some point as the pads get wear out.

Also I noticed some concerns people with disc brakes bikes have, like you shouldn't store them hanging upside down. Don't know if that is valid concern or it might affect only some older types of brakes, but that is something to look into if bleeding tip fails you.

Last edited by vane171; 08-07-20 at 12:34 PM.
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Old 08-07-20, 12:59 PM
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Air bubbles..

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Old 08-07-20, 01:11 PM
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Get new pads, maybe new rotors, then if it still doesn't feel right, bleed it.

Fire the nanny and get a baby trailer.
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Old 08-07-20, 01:29 PM
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Checklist:
-Inspect the system for leaks (especially around the pistons)
-Check pads (and replace if worn)
-Bleed
-Top off fluid in the system
-Adjust reach
-Adjust free stroke
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Old 08-07-20, 01:36 PM
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I don't remember the brand that comes on a Motobecane fat tire bike, but I do know that it would take some extreme wear on the pads to even notice a slight difference in the lever travel. If you've adjusted the clearance on the pads properly, then the only thing it can be is air in the line or a low reservoir. Bleed them. Some great Utube vids on how to service and adjust them you might want to check out, maybe snuggled up to the nanny with a bowl of popcorn after you put the kid to bed. Good luck,
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