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03-12-05, 08:53 AM
I want to move the seat back on the rails by about an inch. There's this nut (is that the right term?) under the saddle which needs an Allen wrench. I tried but it wouldn't budge, rock hard. Am I on the right track? Should I just turn it harder or am I doing something wrong?
Both my seat posts use a single 6mm bolt (installed vertically, with the head facing towards the ground) to hold the saddle rails in place. So it sounds like you're on the right track. Recommend you try a longer allen wrench.
03-12-05, 10:02 AM
Use the long end of the allen key and turn anticlockwise.
Apply a little WD40 or penetrating fluid and use an extension bar.
If the clamp is sticky you will have to dissassemble before you can make any fine adjustments: remove the bolt completely and pull the saddle off, this will separate the upper and lower parts of the clamp. They usually have curved surfaces with horizontal grooves so you can set the tilt of the saddle. Once you have the correct tilt, tighten up the bolt a little then set the saddle rail position.
Apply a smear of grease to the bolt threads and the clamping surfaces to avoid seizing up in future.
03-12-05, 11:52 AM
I prefer to loctite and or lock-washer the clean bolt rather than using grease, a touch of oil or grease on the other parts wouldn't hurt though. I've had saddles come loose and flop all over, not long after tightening the bolt. (On my MTB, during a race, 3 miles of rough technical singletrack to the next wrench :S)
As far as which way to turn a standard right-hand bolt or nut:
turning it clockwise (AKA right) will move it away from you
and counter-clockwise(AKA left) brings it toward you. try it with a loose bolt or nut to see what I meen before trying to loosen a stuck part.
If it is stubborn wack it a couple times with a hammer :)
Rarely you may find a left-hand threaded part which is turned just the opposite of a standard right-hand thread, but left-hand thread is only found on special rotating parts that might loosen if righthand thread was used, pedals for example may try to unscrew themselves if the wrong thread is used but will tighten themselves if the correct one is used.
The saddle is attached to the seatpost by a clamp, which falls into one of two types:
Older (and cheap newer) bicycles use seatposts that are basically a length or steel or aluminum pipe, which narrows down at the top. A separate saddle clamp fits on to the narrow (usualy 7/8"/22.2 mm) section of the seatpost. There is a bolt running crosswise through the clamp, which holds a set of special-shaped washers to the rails of the saddle's undercarriage. When one of the nuts on this bolt is loosened, it becomes possible to slide the rails back and forth and to adjust the tilt of the saddle.
Some of these special washers have serrations which help maintain the angle of the saddle. It is very important to tighten the nuts securely so the saddle will not act as a rocking chair. If it does slip, the serrations will get worn down, and you will be unable to secure the saddle without buying a new saddle clamp.
Most newer bicycles use seatposts which have the saddle clamp built on to the post, which secures the saddle by one or two bolts.
Single-bolt seatposts use a single vertical bolt to hold the saddle rails sandwiched between a pair of grooved blocks. The lower block will have a curved, serrated surface that mates with a matching curved, serrated surface that is part of the seatpost. When the bolt is loose, the blocks may be tilted to adjust the saddle tilt, and the rails can slide back and forth to adjust the front/rear position of the saddle.
Two-bolts seatposts use a pair of bolts to hold the blocks of the saddle clamp. Loosening either one of these allows you to slide the saddle back and forth. Loosening one and tightening the other allows you to adjust the tilt. (If one of the bolts is larger than the other, the larger one should be loosened before making any adjustment to the smaller one.) This type of mechanism allows a finer level of control of the saddle tilt, because it doesn't rely on the meshing of teeth in serrated parts, so this type of seatpost is also known as a "microadjust" seatpost. (Single-bolt seatposts are also sometims called "microadjust," with questionable accuracy.)