Replacement seatpost for 88-89 trek 520
03-02-20, 10:09 AM
#1
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Thread Starter
Replacement seatpost for 88-89 trek 520
I picked up either an 88 or 89 520 in decent shape. The only real issue I’ve been able to identify is the original seat post has a screw holding it together. Id like to replace it with as close to the original as possible. I’ve looked at the trek brochure for info and it only states it is a 220mm micro adjust. any info is appreciated thanks!
Last edited by LBCwanabe; 03-02-20 at 10:14 AM.
03-02-20, 11:20 AM
#2
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You can see there is a Kalloy logo on the head.
The screw does not hold this 2-piece seatpost together unless the bonding were to fail, and I suspect that there may be an interference fit going on as well.
Seatposts fail because of combined loadings, with saddle position, rider weight and dynamic loading all contributing to peak loading leading to failures.
I have also seen aluminum parts and frames fail apparently in part due to heavy press fits acting over many year's time.
Just my opinion, but I believe that with the exception of bikes that will be ridden at a low pedaling intensity, most bikes I see out there would better support their rider's pedaling efforts with the saddle moved forward, and which would help prevent over-stressing the saddle rails, the seatpost, and the post-clamping area of the bike's frame.
Often it is riders who find their hind quarters slipping past the rear edge of the saddle who will benefit more from raising and leveling the saddle (versus sliding it rearward and tilting it back, mistakenly leading to the choice of a shorter stem).
This offers the benefits of 1) better supporting pedaling torque by moving the body's mass balance forward of the bb, 2) quicker, more-effortless and less knee-stressing transition from a seated to standing pedaling position, and 3) less severe of a bending angle at the waist for any given level of aero positioning or of getting one's seated mass in front of the pedals.
A good starting point is to position the handlebars for comfortable climbing off of the saddle, then to re-visit the saddle's fore-aft positioning to achieve comfort both while seated and while pedaling off of the saddle.
The rider of the bike pictured above would appear to benefit from use of a longer stem and with the saddle moved up and forward.
The bike's steering response will also become more stable as weight is transferred to the front wheel.
The rails of what looks like a cheap OEM saddle may likely bend if a rider of decent heft were to ride on it as shown slid so far back on the already-offset seatpost.
Here is a photo of a similar touring model with a fit setup as I have described, best way imho unless it is for just riding along on level roads at a quite-relaxed pace. This bike's seatpost won't be over-stressed beyond what it was designed for!
This position comfortably supports any level of pedaling effort (level, uphill and downhill), while also providing ample steering stability at speed.
The screw does not hold this 2-piece seatpost together unless the bonding were to fail, and I suspect that there may be an interference fit going on as well.
Seatposts fail because of combined loadings, with saddle position, rider weight and dynamic loading all contributing to peak loading leading to failures.
I have also seen aluminum parts and frames fail apparently in part due to heavy press fits acting over many year's time.
Just my opinion, but I believe that with the exception of bikes that will be ridden at a low pedaling intensity, most bikes I see out there would better support their rider's pedaling efforts with the saddle moved forward, and which would help prevent over-stressing the saddle rails, the seatpost, and the post-clamping area of the bike's frame.
Often it is riders who find their hind quarters slipping past the rear edge of the saddle who will benefit more from raising and leveling the saddle (versus sliding it rearward and tilting it back, mistakenly leading to the choice of a shorter stem).
This offers the benefits of 1) better supporting pedaling torque by moving the body's mass balance forward of the bb, 2) quicker, more-effortless and less knee-stressing transition from a seated to standing pedaling position, and 3) less severe of a bending angle at the waist for any given level of aero positioning or of getting one's seated mass in front of the pedals.
A good starting point is to position the handlebars for comfortable climbing off of the saddle, then to re-visit the saddle's fore-aft positioning to achieve comfort both while seated and while pedaling off of the saddle.
The rider of the bike pictured above would appear to benefit from use of a longer stem and with the saddle moved up and forward.
The bike's steering response will also become more stable as weight is transferred to the front wheel.
The rails of what looks like a cheap OEM saddle may likely bend if a rider of decent heft were to ride on it as shown slid so far back on the already-offset seatpost.
Here is a photo of a similar touring model with a fit setup as I have described, best way imho unless it is for just riding along on level roads at a quite-relaxed pace. This bike's seatpost won't be over-stressed beyond what it was designed for!
This position comfortably supports any level of pedaling effort (level, uphill and downhill), while also providing ample steering stability at speed.
Last edited by dddd; 03-02-20 at 11:41 AM.
