Will 10mm really make that much difference?

I have changed from a layback seat post to a straight post and now my seated position feels too far back on the saddle (i.e. sat right on the ridge at the back of the saddle and the saddle is adjusted on the rails as much as possible), leading to all sorts of ‘aching’ issues!

Will extending the stem length by 10mm make a big difference to the way the bike handles? (moving from a 90mm x 10degree stem to a 100mm x 10 degree stem).

Your thoughts please would be very much appreciated.

Leon

my first thought is why did you ditch the layback post?

soobalias – Member

my first thought is why did you ditch the layback post?

Moved to a Joplin, comes in very handy for my forthcoming trip.

I’d be careful about extending the stem – it’s (in my experience) more about the relationship between your bum and the pedals than your bum and the bars.

to try it (and if you run risers) just rotate your bars so they move forward 10mm (shoudl be possible) and see how it feels?

Move your saddle further back on the seatpost rails

wwaswas – Member

I’d be careful about extending the stem – it’s (in my experience) more about the relationship between your bum and the pedals than your bum and the bars.

to try it (and if you run risers) just rotate your bars so they move forward 10mm (shoudl be possible) and see how it feels?

Mmmm? That would have been possible, but it looks like (just tried it) the bars are rotated about as far as they will go?

davidtaylforth – Member

Move your saddle further back on the seatpost rails

Thanks buddy, but already back as far as they will go.

ah, oh well.

you can probably get a stem for a tenner to try and see if it works for you. It will have effects on front end handling as well though.

Sat in the saddle, cranks flat (parallel to the floor), drop a plumbline from the bony point on the front of the knee, it should be inline with the pedal axle. Thats the starting point for a good saddle position, make some small adjustments for personal preference.

sounds like you need the next size up frame TBH – but just buy a £10 stem and try it out.

MSP – Member

Sat in the saddle, cranks flat (parallel to the floor), drop a plumbline from the bony point on the front of the knee, it should be inline with the pedal axle. Thats the starting point for a good saddle position, make some small adjustments for personal preference.

I have just put on an old 100mm stem and done that ^^ and it is spot on! So saddle position is right (may need a little adjusting).

monkeyboyjc – Member

sounds like you need the next size up frame TBH – but just buy a £10 stem and try it out.

Same size frame as I have had for 3 years and no issues before post change?

Can anyone tell me what to expect the differences to be in handling on the front end with 100mm to 90mm? Then I can look out for it on tomorrows ride or will it be ‘obvious’?

I’d say you’ll get used to it unless your frame is too small/short.

MSP – Member

Sat in the saddle, cranks flat (parallel to the floor), drop a plumbline from the bony point on the front of the knee, it should be inline with the pedal axle. Thats the starting point for a good saddle position, make some small adjustments for personal preference.

That’s an old adage for road bikes for people with no common sense (albeit it it’s a reasonable starting place) …as long as seat height is correct there’s a broad range of fore/aft positions one can get used to.

Surely a layback seatpost (like a thompson) and a Joplin are fairly similar in saddle position. Unlike some uppydowny posts, the Joplin is a layback.

cynic-al – Member

I’d say you’ll get used to it unless your frame is too small/short.

How would I know whether the frame is too short? I’ve considered this before but assumed as I have had the same size frame for a while and that any niggles were just down to set up? Is there a way of telling whether the frame is too short for me? It is definitely the right size down tube/ standover etc.

now my seated position feels too far back on the saddle

How long have you been trying it? Changes like that will always feel weird – you need to give it a few rides.

But yes, 10mm does make a big difference imo. It moves your COG which affects bike handling; a saddle further forward will need to be higher which raises COG; it puts more or less weight on the front or back suspension which changes the way they behave too.

The biggest change from sitting further forward imo is very tight windy singletrack – the kind with switchbacks, like at Swinley. Being closer to the back wheel reduces the turning moment of the whole bike+rider making it MUCH easier to negotiate these tight turns.

How would I know whether the frame is too short? I’ve considered this before but assumed as I have had the same size frame for a while and that any niggles were just down to set up? Is there a way of telling whether the frame is too short for me? It is definitely the right size down tube/ standover etc.

Which frame is it? What size is it? How tall are you?