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  1. #1
    Laid back bent rider unixpro's Avatar
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    Arggh!! Seat problems

    I've been having a real fight with my bike for the last few months. Back in October, I changed jobs and pretty much doubled my commute to just under 40 miles/day. The route takes me over city streets and MUP trails, with something like a 2K elevation change each way. There are parts of the route that are rough, but most are pretty benign. I don't usually go teribly fast over the rough parts.

    Since I started on the longer commute, I've had problems with the tires and wheels, lights, faring, and fenders. I seem to have worked all of those out, but now I've got a seat problem.

    The bike is a Giro 20, and I'm a short (5'7") heavy (225) guy (some fat, but more muscle). Yesterday on the ride home, the seat slipped back unexpectedly when I was cresting a hill. I figured that the clamp had come loose, so I stopped, reset the thing, and went on. Over the course of the rest of the commute (probably about 5 miles), I had to reset the seat thrice more, for a total of 4 times.

    The bottom of the seat has some kind of a cross-member on it that looks like a bolt might have fallen out. I don't have enough knowledge of the geometry to know for sure, though. I guess I'll take it back to the shop, again. This is getting frustrating.

    These bikes are supposed to be the commuter version of the Giro, I was told. Has anyone else had these kind of issues using them for daily, long-haul commuting?

  2. #2
    Senior Member Dchiefransom's Avatar
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    Not only go back to the shop about the seat, but I'd think about getting the widest tires that would fit on there. Those would take up a lot of the roughness that you ride over. The more the tires absorb, the less the bike components absorb.
    Silver Eagle Pilot

  3. #3
    Senior Member oddball's Avatar
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    Jul 2008
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    I have had a similar problem as yours but not as extreme. I have a Giro 20, I am 6'2" 250. I discovered my seat slipping back when I started getting small pains on the inside of my knee and Achilles tendon. The seat was sliding back very slightly with each ride. I took the seat off of the clamp and then removed the clamp itself. I then cleaned the area where the clamp went around the frame with a degreaser. There didn't seem to be much grease on the rag but a lot of grit. I believe that the grit had worked its way between the clamp and frame and then acted like tiny ball bearings. When I reassembled the clamp I tightened the bolts on the top leaving a space on the top of the clamp about the thickness of a dime. I replaced the quick release with a bolt and torqued it it 55in-lbs. 1000 miles later it hasen't moved.

  4. #4
    Laid back bent rider unixpro's Avatar
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    Well, as it turns out, I now know a lot more about seat geometry and construction.

    There are 4 bolts that hold the seat pan onto the clamp that slides up and down the boom. The clamp is actually two half-clamps that join at the top and the bottom. When you tighten the quick-release on the seat, you're actually closing the bottom of the clamp. The top is attached to the seat pan.

    I had lost two of the bolts, and one had broken. The result was that half of the clamp was free on the top, so the thing wouldn't close around the boom. This allowed the seat to seek its own position, irrespective of my wishes.

    Now that the mechanic actually believes I ride as much as I said I do (why don't they *ever* believe you??), I've got 4 new heavy-duty bolts, a stronger "no stretch" chain (the old one was in dire need of replacement), some new brakes (the old were on their way out as well), and new heavy-duty cable and housing for the rear derailer. When I get enough cash, I'll replace the wheelsets and brakes with a switch to disc/

    At least now he understands that I'm serious when I tell him I'm putting 150-200 miles/week on the bike under all riding conditions.

  5. #5
    Senior Member oddball's Avatar
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    I lost one of the four bolts that the seat pan on while on a ride. Turns out a water bottle cage bolt has the same threads, something you might want to keep in mind in case of emergency. Mine are all loctited in now. Does your seat clamp have one or two bolts across the top? Bacchetta has just changed to a clamp with two top bolts. If you have only one it's the old style. I still have the old style and haven't had any problem since I used the fix I explained in previous post. That top bolt that the seat is resting on is called a "Frankenstein bolt" or "franky bolt" by the guys at Bacchetta.

  6. #6
    Laid back bent rider unixpro's Avatar
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    I have the newer seat, apparently, with 4 bolts (2 on each side). I think the Loktite might be a good idea.

    The ride in this morning was pure heaven. Apparently I've been fighting the bike for at least a month without realizing it. I guess you never know how much pain you're in until the beating stops, eh? Between the new chain and cables, the seat that stays in one place, and the general tuning of the gears that was done, it's like riding a new bike.

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