Before and After

Before

After

No good blog emphasizing fatness would be complete without Before and After photos...

In addition to the pump, bottle cages, handlebar, rim sticker removal, grips, and cog, some of you may have identified the squishy fork as a difference between the photos. 

That's a 2012 Manitou Tower Pro in 100 mm flavor with a XX-Firm Spring (Clyde Ride kit) installed. There's a lot of information out there that sometimes contradicts other information sources, sometimes references another travel or year, or is simply too long to try to comprehend in one sitting.  So here is my post to document my experience of putting the XX-Firm spring in a 100 mm travel 2012 Tower Pro.

In addition to the Manitou website (where you can download the manual as well as service guide), I consulted these sources:
twentynineinches.com 
29eronline.com
MTBR (Even though it's the print view, that link includes all the 400+ responses...ugh)

Parts, Tools, and Oils/Grease:
Manitou recommends 5WT fork oil.  I have the email from them.  They said 10WT is too thick for their shim stack.
I'm going with Motorex stuff (their carbon grease is awesome - highly recommend):
5WT Fork Oil 
5W-40 Semi-Bath Oil
Manitou Prep Grease

I also ordered one of these to measure damper oil level:  Motion Pro 08-0121 Fork Oil Level Tool. I ordered everything from Amazon.

To put an XX-Firm spring in a 100mm fork, you need the XX-Firm Spring for the 120mm fork and the pushrod from the Medium kit for the 100mm fork.  The stock fork came with Firm Spring kit.

You'll need to call Manitou, get the part numbers you need, then have your local shop call and order the part. I'm sure there's another way to do it, but I'm not going to post up to order a particular part number from PricePoint, and then later find out Manitou changed their offerings or whatever. PricePoint obviously has a relationship with Manitou, as their page is linked from the Manitou home page. Ordering the $200 tuning kit for the damper is tempting, but more tempting is to call Suspension Experts and ordering whatever pieces I need, if I get to that point.

After installation of the XX Firm spring in my fork, I noticed some play in the fork.  Basically it felt like the spring or air wasn't pushing the lowers all the way out.  A quick email to Manitou revealed that in fact I needed the pushrod from the medium kit, which they dropped in the mail free of charge.  After the new pushrod installation the play is gone and I've begun the process of tweaking the fork.

XX Firm Ride Kit for a 120mm fork

XX Firm spring on Left
Firm (Stock) spring on Right

Pushrod from Medium kit on Right
Stock (Firm kit) pushrod on Left

Oil height (5WT Fork Oil) in all Tower Pro models is 85-90mm with 87mm nominal. I'm going to max this out to 90mm to get things running a little stiffer. Oil height is listed on page 23 of the fork manual. If this plus air pressures don't get me to where I want, then I'll get into shim stack adjustments and calls to Suspension Experts. Sag settings for the 100mm are 15-20mm; I'm going for 15mm.

Semi-Bath oil goes on top of the air piston (5 mL) if you are doing MARS service. Semi-Bath oil also goes in each side of the lowers (16 mL) if you didn't keep it in the fork during service.

Tips during disassembly/assembly (Watch the video on 29eronline linked above):

Casting Removal
I had to drive the lowers all the way to the crown, bleeding off as much air as possible. This resulted in some oil getting into my shock pump. I don't think I lost too much, but that's half the reason why I bought more oil and the level tool. I haven't gotten around to checking it yet. To loosen the compression rod screw, I placed the steerer tube on a doormat, used one hand to drive the lowers to the crown, and the other hand with a ratchet to loosen the bolt. You need a way to drive the compression rod into the bottom of the lowers. Otherwise it just spins inside and you get REAL irritated. The little trick in the video didn't work for me. During all this, the fork is upside down. The oil in the lowers will stay inside. Once the lowers are free to be pulled off, I put painters masking tape over the bolt holes to hold the oil in. Then slowly slide the lowers off. I used a trash can in case the tape didn't hold.

Spring/Pushrod Replacement
Follow the Manitou Service Guide, but if you are only swapping spring and pushrod then you don't need to do anything at the crown (like removing the air cap). You can get to the spring and the pushrod from the bottom with a variety of long tools. I opted for a Craftsman Pick Up Tool, which is invaluable for correcting the combination of clumsy hands and small parts near crevices.

Castings Installation
Slowly slide the stanchions back into the lowers to get them started. Turn the fork upside down. REMOVE the tape. If you don't, you'll build pressure in the lowers and blow the tape off, probably with some oil.

A bike stand makes the whole process a lot easier and other than being pretty nervous about tearing apart a brand new fork, it is a fast and easy process.

ps I've dropped about 10 pounds so far this year.