Kai-ming's kitchen

Discuss light weight issues concerning road bikes & parts.
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Leviathan
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by Leviathan

best way to control the flex may be with different elastomers a la look seatpost.

kai-ming
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Joined: Mon Dec 03, 2007 12:53 pm

by kai-ming

You probably don't need that much of movement from the seatpost, especially heavy weight rider.

thisisatest - I think you guys arent realising how much movement a seatpost gets in a frame. If one were to imagine the seat tube having a much larger bore than the post's shims, and the post clamp pinching down on the upper shim, it's easier to see that the seat tube in fact "gives" more locally and less uniformly. Reality is similar to this, but on a smaller scale.
Many, many frames get "creaking" from excess seatpost hanging out inside the frame moving around slightly, even frames with a constistent interior shape all the way down.

cervelo - http://www.youtube.com/watch?v=ipjuWSTM ... ure=relmfu 4:08 - 4:14

by Weenie


kai-ming
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Joined: Mon Dec 03, 2007 12:53 pm

by kai-ming

Has anybody experienced this? The Colnago seatpost/saddle bottomed on me, a 130lbs rider. :oops:
Below are pictures before saw/Dremel, the bolt at the rear had been removed for cutting in the second picture.
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Below are pictures after saw/Dremel.
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SUCycling88
Posts: 94
Joined: Mon Jun 14, 2010 2:32 am

by SUCycling88

It doesn't surprise me being the aspide saddle was one of the most flexible saddles I've ever ridden (then again I'm 180lbs).
'

kai-ming
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Joined: Mon Dec 03, 2007 12:53 pm

by kai-ming

Yes, it is Aspide FX made for Colnago.Image

No, no body experienced that? I am surprised.

peruffo
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Joined: Sun Oct 26, 2008 3:12 pm

by peruffo

I use SSM Aspide Arrowhead and when using the type of seatpost clamp as the OP, I have to cut the bolts to size, so they don't stick out the top. This way, the base of the saddle never touches the clamp. I weight 135 lbs (69 kg).

If you cut the saddle base, you'll have even more flex, so I think sooner or later the bolts will start to "eat" the leather cover.

kai-ming
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Joined: Mon Dec 03, 2007 12:53 pm

by kai-ming

69kg = 69x2.2lb = 151.8lb :mrgreen:
You are right, cutting the saddle base would make it more flexible. When I ride on the saddle I always feel that the saddle is a little too stiff compare to my other saddles, I was willing to give it a try anyway. If it bottom because of the cutting, I can always swap the saddle of my other bikes with a different seatpost. :beerchug:

kulivontot
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by kulivontot

Use shorter bolts? :noidea:

RichTheRoadie
Tinker, Taylor, Tart
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Location: Sydney, Aus.

by RichTheRoadie

That's an old saddle - I wouldn't be surprised if it's just knackered.

mrfish
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Joined: Wed Mar 28, 2007 12:49 pm
Location: Near Horgen, Switzerland

by mrfish

+1 on all points above. The problem is not unusual.

- Cut the bolts not the saddle - you don't want a bold embedding itself in your lower regions
- Try a new non bananaed saddle
- Switch to a saddle with more clearance
- Switch to a Campag seatpost or one with a with traditional or sideways clamp (and shim if it's a 28mm frame)

kai-ming
Posts: 97
Joined: Mon Dec 03, 2007 12:53 pm

by kai-ming

kulivontot wrote:Use shorter bolts? :noidea:

Half correct, the bolt at the front is difficult to replace if not impossible. :mrgreen:

kai-ming
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Joined: Mon Dec 03, 2007 12:53 pm

by kai-ming

BikeTart wrote:That's an old saddle - I wouldn't be surprised if it's just knackered.

That sounds like comment from a bike shop. :roll:

kai-ming
Posts: 97
Joined: Mon Dec 03, 2007 12:53 pm

by kai-ming

Image
This is a TranzX 31.6 setback seatpost. The heavy bit is really at the mounting head. I have cut short the post at the head end, removed the head, drilled it including drilling the socket bit that is glued to the post (no photos was taken at the time it was done) and epoxyed it back to the shortened post. I think there is a saving of around 100g as far as I remember.
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This is how it look when installed to a bike.


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Tuning of a Shimano R600 crank arms.

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This is the ugly un-finish bit. The weight of the tuned R600 crank is about the same as a 7800 DuraA.
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It is strong enough to be my travel bike.

kai-ming
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Joined: Mon Dec 03, 2007 12:53 pm

by kai-ming

Kai-ming's kitchen! I like the caption. :mrgreen:

by Weenie


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prendrefeu
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by prendrefeu

A true tinker-er!
It's great to have a forum member looking to experiment. Great work!
Exp001 || Other projects in the works.

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