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• #2
It's simply to facilitate fit - for example I had to swap the inline post on my road/audax bike for one with 25mm setback because I couldn't quite get the saddle back far enough to achieve the proper* 90 degree (dead straight shin bone - hang a plumb line from the knee) angle with forward crank at 3/9 o'clock.
Edit - forgot to add. The key component of a 'more relaxed' set up is to simply reduce the drop from saddle to handlebars, it makes far more difference than people give credit for even if you are still quite stretched out. Some frame geometries facilitate this (think Spesh roubaix/allez/langster) whilst others have a more 'racy' geometry which would need lots of spacers on the steerer as well as an angled stem to achieve a similar riding position (like the Ribble winter frames or Cannondale CAAD frames). If you're like me with long legs and relatively short arms then it's a right PITA.
Hope that helps.
*proper for my riding style/purpose - would be different for say a TT set up.
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• #3
Cheers for the advise, I think I have the angles right with the straight post but could do with checking...
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• #4
There are also a couple of other effects....
Having your bum further back engages the glutes more - this is excellent when your out riding for longer distances as the glutes are a very strong muscle group, and engaging thems means your quads don't get so caned.
Having your bum further back takes load off your arms - if you get sore shoulders, your saddle might need to go back.
Moving your bum around changes the weight distribution on the bike. Different frames put the bottom bracket in different positions relative to the front and rear axles (defined by front centre length and chainstay length, plus BB drop). If your bike is designed to be ridden with the weight back, and you fit an inline post, you will put more load on your front wheel. Which may be a good or bad thing!
Personally, I think more people could do with using more setback, but that's just another way of saying that a lot of people have poorly fitting bikes!
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• #5
Dredge.
I need a setback seatpost but was wondering if there are alternatives to a Thomson.
I had a Miche Supertype which I thought might do the job, but it broke coming out of an old bike.
Any suggestions, anyone selling a 27.2 in silver?
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• #6
worth noting the bent Thomson still has less setback than a lot of 'normal' posts. Just that the straight Thomson has zero setback.
So alternatives to Thomson with the same amount of setback are just about any post on the market (other than the few zero setback posts)
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• #7
Cheers Kerley, glad I asked.
Anyone have suggestions of 'normal' ones that are quite set back? I'd like it fairly traditional looking.
EDIT.
This is the answer:
http://www.tokyofixedgear.com/shopexd.asp?id=649&bc=no*These polished two bolt seat posts have a generous 30.2mm of setback, among the longest ever. This is very important for those who ride Brooks saddles which have very little fore-and-aft adjustment due to the short rails.
The VO posts are internally ovalized to reduce weight to 254gms. The adjustment is from the bottom and the two bolt design makes it easy to precisely adjust the seat angle. Also note that the head is integral with the post, not pressed on as on many modern posts. This makes them stronger and lighter. The quality and finish is second to none.
27.2mm only x 300mm. Maximum height (above the min. insert line) is about 23cm.*
After googling the purpose of having a setback I just wanted to gauge a few opinions on those who use them. Is there a pronounced difference in power and efficiency?
Personally, I'm looking for a more relaxed bike geometry and wondered if this might help. Obviously I realise that it's very much horses for courses...
Any thoughts?