Seatpost, or stem change?

Talk about anything.

Moderators: Bearbonesnorm, Taylor, Chew

Post Reply
User avatar
ootini
Posts: 1802
Joined: Tue Mar 24, 2015 5:45 pm

Seatpost, or stem change?

Post by ootini »

I've noticed that after a while on a ride I seem to stretch out a little especially when on the drops.
It feels like my "arse bones" end up on the rear rail of my C17 saddle, as opposed to in the saggy bit.
I had thought about a layback seatpost, to shift the saddle back a bit, but then worried I'd end up too far behind the BB. Would I be better with trying a longer stem instead ?
jameso
Posts: 5036
Joined: Tue Nov 06, 2012 1:48 pm

Re: Seatpost, or stem change?

Post by jameso »

Being behind the BB isn't usually a problem unless you're out of balance. There's a good essay by Keith Bontrager on all this. Basically if you need to stretch out, think about the position a downhill skier takes - to reach out you have to stick your arse out also, or you fall forwards. IE, it's not really about reach. Think of your C of G being somewhere near your navel and where your C of G is on the bike (and where it is in relation to your feet / the BB) being important. Reach just allows you to get centred and in balance for the long haul.

Short answer :grin: - try the layback post first, don't worry too much about where the BB is. Sounds like the longer stem *may* just exaggerate a position that *may* already be a bit forward-biased.
User avatar
ootini
Posts: 1802
Joined: Tue Mar 24, 2015 5:45 pm

Re: Seatpost, or stem change?

Post by ootini »

Cheers for the info James

Assuming the saddle is fitted as far back as possible, how much if a shift would I expect using a layback? Having never used one, I've no idea.
jameso
Posts: 5036
Joined: Tue Nov 06, 2012 1:48 pm

Re: Seatpost, or stem change?

Post by jameso »

ootini wrote: Thu Mar 12, 2020 7:57 pm Cheers for the info James

Assuming the saddle is fitted as far back as possible, how much if a shift would I expect using a layback? Having never used one, I've no idea.
15mm or so usually, Thomsons are 16mm layback, 15mm is common, rare they're more than 20mm. 15mm's not a lot in distance but it's a useful adjustment in bike fit terms. You might end up with e saddle (eg) 10mm further back with the saddle rails a bit more central in the post clamp, no bad thing. You could measure the tip of the saddle to the centre of the stem cap as a reference before you move anything?
slarge
Posts: 2641
Joined: Mon Aug 22, 2011 4:49 pm
Location: MTB mecca (Warwickshire)

Re: Seatpost, or stem change?

Post by slarge »

Is the fit of the bike the problem, or do you have a weak core that allows your body to “relax” too much?
User avatar
ootini
Posts: 1802
Joined: Tue Mar 24, 2015 5:45 pm

Re: Seatpost, or stem change?

Post by ootini »

slarge wrote: Thu Mar 12, 2020 10:16 pm Is the fit of the bike the problem, or do you have a weak core that allows your body to “relax” too much?
I'm not the fittest person, so this is quite possible.

Not sure how I'd know though...
jameso
Posts: 5036
Joined: Tue Nov 06, 2012 1:48 pm

Re: Seatpost, or stem change?

Post by jameso »

a weak core that allows your body to “relax” too much?
Steve, is this something that happens that you can expand on, or more of 'just a thought?' Interested, thanks. Do you mean the way your core is less able to hold you up or hold a certain position? I have noticeably less core strength since I stopped climbing and seem to be getting new discomforts, may be related. No hijack intended, just interested in the topic generally.
User avatar
Bearlegged
Posts: 2292
Joined: Fri Jun 30, 2017 5:00 pm

Re: Seatpost, or stem change?

Post by Bearlegged »

Having been doing yoga for a bit over a year now, I've found that my core strength has improved, and this has led to much more comfort on the bike (whereas previously I'd develop lower back pain and sore shoulders from hunching too much).
However, I find that my posture has lengthened while on the bike. This would seem to be at odds with the suggestion that ootini's lengthening on the bike is connected to lack of core strength, I'd expect it to result in a shortened posture.

*sample size = 1
**I am not a physiologist
slarge
Posts: 2641
Joined: Mon Aug 22, 2011 4:49 pm
Location: MTB mecca (Warwickshire)

Re: Seatpost, or stem change?

Post by slarge »

James / Ootini
I think it's quite well known that cycling does little for core strength, but a good core is needed to stay "stable" on a bike - not that popular with roadies but more essential as you need to "handle" the bike (offroad etc). I've found over the years that since I stopped circuit training my overall posture and core strength is weakening, and I've also started getting lower back pain on the bike if I don't use my core (and the weaker it gets the harder that is).

My theory is that lots of "fit" issues are due to poor posture, which can result from poor core strength. No research behind this that I can be arsed to read, but it seems a fairly straightforward link from poor core strength to poor posture which can give the impression of poor fit. Of course, having a well fitting bike in the first place is essential, but if a bike becomes more uncomfortable the longer you ride it then maybe it's posture related - the more fatigued you get the easier it is to let the posture "drop".

I think we often try to buy our way out of some basic problems (I'm sure any doctor would agree) that a bit of strength training or hard work would fix "for free", it's in our nature as humans are basically lazy. A strong core has many other advantages.

Like I say, it's all my theory but somehow arrived at through experience and simple logic (I like simple).

My daughter is a physio, but that's had no bearing at all on my amateur wisdom :grin:
jameso
Posts: 5036
Joined: Tue Nov 06, 2012 1:48 pm

Re: Seatpost, or stem change?

Post by jameso »

That all makes sense.
I think we often try to buy our way out of some basic problems (I'm sure any doctor would agree) that a bit of strength training or hard work would fix "for free", it's in our nature as humans are basically lazy. A strong core has many other advantages.
I agree, I went through a phase of bike spec+design to solve some personal fit issues and hand/nerve problems and then after that into a period of making myself fit a bike where the geometry worked better one way, via needing to stretch a lot more to be ok on it for distances. Fitting and adapting myself to a bike was more interesting. Need to get started on the core strength though, at least more than 'ride MTB more often'.
slarge
Posts: 2641
Joined: Mon Aug 22, 2011 4:49 pm
Location: MTB mecca (Warwickshire)

Re: Seatpost, or stem change?

Post by slarge »

ootini wrote: Fri Mar 13, 2020 8:08 am
slarge wrote: Thu Mar 12, 2020 10:16 pm Is the fit of the bike the problem, or do you have a weak core that allows your body to “relax” too much?
I'm not the fittest person, so this is quite possible.

Not sure how I'd know though...
Can you hold a plank position for 2 minutes? Maybe go to a yoga or pilates class and see what "core" is all about - pilates for me was very informative about how to stretch and gave me some basic exercises that I can do anywhere (if you're keen, get a Pilates DVD - we've got a few and apart from the lady being very very pleasing on the eye, it really helps with flexibility and strength.
Post Reply