Fixing up a new-to-me DH bike

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Fixing up a new-to-me DH bike
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flag JRadM
Posted: Jan 12, 2015 at 10:01 Quote
I bought a bike recently hoping to use it to get into better shape. I race dirt bikes and this year I am moving up a class with one of the series I compete in. I will now be riding at an “A” level, so the races will be longer than before (usually 2.5-3.5hrs) so I could use some extra endurance. I am starting this thread to document the work I’m doing to my used bike and hopefully get some advice about how to get it ship-shape.
The bike I purchased is a 2009 Rocky Mountain Flatline Pro.

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I bought a DH bike in part because it looks most similar to riding a dirt bike.

I’m not new to mechanics generally – I do all of my own maintenance on my dirt bike. However, this is the first time I’ve ever worked on a bicycle. Many of the parts seem similar to my dirt bike. I don’t anticipate any issues working on the fork and shock, but some of the other bits are alien to me.

When I picked the bike up it was living up to its “flatline” name:

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Since the tires were losing air I figured the wheels were probably the best place to start the tune-up.
I removed them from the bike and was pleased to find they fit right on my dirt bike wheel stand.

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Then I removed the tires and cleaned up the dried tire sealant.

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While the tires were off. I struggled to figure out how to service the wheel bearings. This is not the same as a dirt bike.

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On my dirt bike, although the bearings are sealed, I knock out the wheel spacers and fill the area between the bearing and outer seal with grease to keep out water. When it gets contaminated, I wipe out the grease and refill it. This greatly increases the bearing life.

When I finally got into the bearings on my wheel, everything looked dry. Is this normal? I don’t normally mess with the seals on the bearing itself since they are so easy to ruin, but since it didn’t look like grease had ever been added and I didn’t know how old they were, I figured I would try to carefully pry them open.

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The front bearing looked dry. The rear had a bit of grease visible inside. I filled them both up and pressed the seals back on. Then I filled the space between the bearing and the outer seal and reassembled. I’m curious, is this is something other people do? I can’t see any issues with it other than if I get it wet I will have to take it apart and re-grease again and it probably adds a few grams. It occurs to me that people probably don’t ride through mud and water as often as dirtbikers, so maybe this is overkill?

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Also, what are the copper-colored parts of the spacer for? Is this part worn?

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I remounted the tires, then wasted an hour and half driving around town to find an adapter when I realized the presta valves wouldn’t work with my normal air chuck. When I finally did find the adapter, I could only get the rear tire to seat. The front was just losing air in too many places for the bead to set.

I assumed I should mount the tire, seat the bead, then use a tire iron to pry it away from the sidewall in one spot to add the Stan’s sealant. After my frustrating attempt to seat the tire, I’m now thinking this might be wrong.
Any tips? Should I add the sealant before trying to seat the tire so it can help fill the leaks? Should I get the bead wet to help it slide on?
flag JRadM
Posted: Jan 13, 2015 at 7:58 Quote
Got the tires mounted up with some Stan's sealant. That was kind've a pain. Had lots of little leaks around the bead that I had to work the sealant into.

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I put the wheels back on the bike hoping to go for a bit of a ride before taking it apart to service the shock and fork. No dice though - turns out the rear wheel is pretty badly out of true. Guess that's what I'll work on tonight.

I noticed the brakes seem pretty weak too, so I ordered some new pads.
flag JRadM
Posted: Jan 15, 2015 at 6:36 Quote
I worked on truing the wheels last night. I think the front is pretty good, but I'm not sure about the rear. It's heaps better than it was, but there's still some wobble visible when I give it a spin. I'll post up a video later and hopefully someone with some expertise can comment if that's good enough, if I need to replace something or if I just need to keep at it.

I also did some repair to the seat. The stitching had come loose at the rear.

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I will likely just buy a new seat eventually, but I don't like things to look busted. So for now I spent some time darning it.First by sewing all the way around the outside edge, then by sewing the two halves together. I usually try to match the thread to the repair, but sometimes I like picking a contrasting color so the bike looks like it has some scars.

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flag JRadM
Posted: Jan 16, 2015 at 6:18 Quote
Do these wheels look to be trued well enough? It took a lot of fiddling to get them this straight. The front seems fine to me, but the rear still has a slight wobble...
flag JRadM
Posted: Jan 19, 2015 at 9:34 Quote
I don't seem to be generating any responses. Guess this thread is just documenting my slow progress.

Had more time to work on the bike this weekend, so I removed the fork and shock

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Opening up the RC3 leg, things didn't look so hot:
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I also had a leak at the bottom:
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Here's a comparison between new oil and what came out of my fork.
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This is the preferred method of driving in seals right? Razz I pushed in the new seal with my fingers to get it started, then put the old seal on top of that plus these two large sockets. Then went to town with my hammer.

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Success:
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flag JRadM
Posted: Jan 20, 2015 at 6:38 Quote
Next up, the shock:
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First let the air out, then remove the valve core.
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Do the same for the valve on the piggy back chamber:
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Remove this retention ring:
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Then this part slides off:
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Use either a strap wrench or oil filter wrench to unscrew the air chamber:
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You should be using a large box-end wrench on the piggy-back, but it's not very tight so a crescent wrench will get the job done. Just beware of scratches if you slip. Ps. There shouldn't be oil here.
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Guess I forgot to take pictures of removing the piggyback chamber and IPV. It just unscrews and you can push the IPV through carefully with your finger.

If you want to remove the compression stack (not necessary for an oil change, just unscrew the tiny allen bolt on top of the compression adjuster. Then the knob can be pulled off. Careful, there is a tiny spring and sphere under the knob.

Then from the otherside, you must carefully pry up the o-ring sitting in the groove just above the compression stack. After that, the compression stack can be removed and there is a spring underneath.

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My compression adjuster was stuck.
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When I took everything apart, I realized one end of this part had snapped off inside the compression adjuster knob.
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Even with the compression stack removed and using a pair of pliers to turn the broken part, it remained stuck so I presume its best to replace the whole stack.

In this picture, you can see it was turned so hard this part started to bend:
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My theory is that the shock was leaking oil, so the last owner probably kept tightening the compression knob to compensate.

I ordered the new bits from Marzocchi and was pleased to find they were cheaper than I expected: they said around $25 for the whole compression stack.
flag Loki87
Posted: Jan 20, 2015 at 8:28 Quote
Just wanted to give some response.
I did actually enjoy reading this thread.
It´s kinda interesting to see that bike come back to new life. And i like how well you documented everything.
Might be useful to someone who just bought a used bike as some kind of guideline how to get things back in shape without much money.
So keep it up, you got at least one follower Wink
flag JRadM
Posted: Jan 20, 2015 at 10:29 Quote
Cool. i was beginning to think it was just me and the crickets. tup
flag jwollerton
Posted: Jan 21, 2015 at 8:24 Quote
Loki87 wrote:
Just wanted to give some response.
I did actually enjoy reading this thread.
It´s kinda interesting to see that bike come back to new life. And i like how well you documented everything.
Might be useful to someone who just bought a used bike as some kind of guideline how to get things back in shape without much money.
So keep it up, you got at least one follower Wink
+1
flag JRadM
Posted: Jan 23, 2015 at 9:48 Quote
I'm somewhat stalled right now as I wait for some parts and tools. I ordered a new oil seal kit and valve stack for the shock, a new rebound adjuster for the fork, new bars, seat and seat post and a few other bits.

I must say, the two fellows I contacted at Marzocchi Canada were a pleasure to deal with. The parts were cheaper than I expected and they even gave me some tips for bleeding the shock.

I took apart the headset/triple clamps while I had the forks off.

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Things were a bit grungy. I think I need to replace the bearings and races. For now I cleaned everything up, then pried open the seals on the bearings to add some lube. The bottom bearing seemed fine, but was a bit dirty. This top bearing slid out with finger pressure - I assume it should be an interference fit.

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Are double crown headsets somewhat universal or can anyone explain how I figure out what to order?
flag JRadM
Posted: Jan 23, 2015 at 10:22 Quote
According to bikepedia, my bike came stock with a "1 1/8" - 1 1/2" integrated FSA Orbit Z 1.5R" headset. My forks aren't stock (I have Marzocchi 888 RC3 vs the ATA WC that came stock).


Would something like this work?
http://www.ebay.ca/itm/J-L-1-1-8-1-5-1-1-2-Tapered-Headset-Sealed-Cartridge-Bearings-Semi-Integrated-/291174507004?pt=Cycling_Parts_Accessories&var=&hash=item43cb5a61fc
flag JRadM
Posted: Jan 28, 2015 at 6:27 Quote
I swapped and bled the brake hoses last night. I wanted to run the brakes moto-style so I don't have to pause and remember which side does what every time I stop.

It was a relatively straight forward process.

Just slide back the plastic caps on the hose near the master cylinder, then the hose has an 8mm part that holds the hose on. Unscrew, rock the hose back and forth as you pull and it pops off.

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If you remove the caliper and pads, you can pump the brakes to push the caliper piston further out, forcing some extra fluid into the lines to help with bleeding afterwards. I didn't bother since I knew my brake fluid was very old.

You're also supposed to change the "olives" on the end of the hose since they crush to fit the MC. I didn't have any handy, so I'm crossing my fingers I can get away with it this once. I'll keep an eye out for leaks.

When the swap was complete, I used a rag to soak up the fluid in the MC (that's why it's empty in the first picture), then added fresh stuff and tried to bled the brakes the conventional way. That was not successful. I suspect I introduced too much air into the lines.

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I ended up back-bleeding it from the caliper with a short piece of hose and a 50mm syringe.

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Now my brakes are much firmer than before.

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flag THE15
Posted: Jan 28, 2015 at 6:46 Quote
Great thread - the olives will be fine as long as you've tightened the 8mm i have the same brakes and have done it numerous times.

As for your wheels are they definitely tubeless if so you need to ensure that you have tubeless rim tape and also tubeless tyres otherwise you'll struggle to keep them up. Might be easier to run tubes just to get you up and running.

For your headset you will be able to find replacement sealed bearings for it rather than replacing the whole unit. It doesn't matter that you have different forks they have the same 1 1/8 steerer tube.

Be careful with all bearings as most tend to be sealed you may be pulling the case apart when often replacements are relatively cheap like the below;
http://www.chainreactioncycles.com/s?q=headset+bearing
flag JRadM
Posted: Jan 28, 2015 at 8:14 Quote
Thanks for the tips THE15.

For the rims, I assumed I didn't need rim tape since the rims don't have holes for the spokes. They look like this on the inside except for the hole for the valve:

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I didn't realize I could just buy new bearings for my existing headset. I'm wondering if that's worthwhile though - couldn't I just buy this headset for ~$40 and be done with it?
http://www.chainreactioncycles.com/ca/en/fsa-orbit-mx-headset/rp-prod2217
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