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The other day I left my mountain bike upside down overnight as I was changing a tyre. The next morning i had a puddle of what seem to be oil next to the handle bar. Does anyone have an idea where is this coming from? As far as I am aware my disk brakes are not hydraulic would it be from my front shocks? If so how do you replace, and is it safe to ride it now before putting some oil in?

This is my bike:

http://www.performancebike.com/reviews/performance/power/pwr/product-reviews/Specials/Spin-Doctor-Pro-Bike-Build/MONGOOSE/p/30__1446-2009-Mongoose-Canaan-Comp-Mountain-Bike-U-S-Exclusive.html

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  • I'm pretty sure your brakes are hydraulic. – Batman Nov 7 '14 at 11:19
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    A bicycle should never ever be turned upside down, There is no reason for this except if you want to scratch the saddle and the bars. After you've removed a wheel the bicycle rests on the left side! – Carel Nov 7 '14 at 14:31
  • See Rule #49. – andy256 Nov 9 '14 at 9:02
  • @Carel - Sorry, but I disagree. When you have to fix a tire on the road turning the bike upside down is the best way to handle it. Unfortunately, most newer bikes have cables arcing up off the handlebar, so this is not possible on newer bikes, making on-the-road repairs much more difficult. And, of course, hydraulic brakes also make it a problem. – Daniel R Hicks Nov 9 '14 at 11:59
  • @DanielRHicks - Sorry, but the dropouts are designed to work with the bike the right way up. It's more difficult to get the wheels in and out when it's upside down. – andy256 Nov 9 '14 at 23:55
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Presuming it came out of the bike, probably oil from Hydraulic brakes. Although the link does not specify things in detail - A 2009 bike with Tora Rock shox and Deore components would almost certainly have had hydraulic brakes.

Check the brakes are working and not spongy. If in any doubt take it to the LBS for a check over - a leak from the shocks needs fixing but would not be the same seriousness as a leak from brakes.

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  • Looking at the spec elsewhere, it looks like it had Avid Juicy 3s as standard. – Holloway Nov 7 '14 at 9:26
  • DOT brake fluid feels oily too (which the Juicy's should have - but if its not a DOT brake, mineral oil is obviously oily too). I would bet that it is the hydraulic brakes though. – Batman Nov 7 '14 at 11:20
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Almost certainly oil from your shocks or brakes. Neither are designed to be upside down.

Another possibility is that in rare cases if the drain holes in your bottom bracket or chainstays are plugged up, you can get moisture accumulation in your frame. That can mix with oil and dirt from your BB and headset and drain out of other areas when the bike is upside down. The resultant black gook can look like oil, with the only caveat that it will actually evaporate.

If you leave your bike outside in the rain, it's a good idea to: 1) don't do that; 2) make sure the drain hole is clear if you have one; 3) if not, occasionally remove the seat and try to drain moisture out that way.

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