following from my thread a few days ago,this one bike fit session is happening this afternoon. I have done a load of research on the geometry and measurements and have a good idea on the outcome as to which frame size fits me. Question I have though is, for a medium sized frame, what difference will upping the stem from 100 to 110mm have on the feel/handling, if any ?
many thanks
Not a lot.
Road bike fit is determined by top tube length seat height saddle and bar drop etc etc and stem length, dropping a spacer on my mate bike loses him about 80 watts! your fit may dictate more than a new stem!
wookster, indeed and quite agree, infact the fit is likley to be bringing me down a frame size as well, however I am fairly certain that amongst other things the stem will be going from 100 to 110, hence my query.
dropping a spacer on my mate bike loses him about 80 watts!
PMSL!!! Where on earth did he get this information from??!!
That's about the same as going from a road bike to a full aero set-up for time trialling. All that money I spent on a time-trial bike, aero suit and helmet ... when all I needed was a £1.99 spacer. 
as for 100mm --> 110mm stem. You could save your money and just slide the saddle back 1cm on the rail?
i wouldn't worry. if it was getting shorter then you probably are on too big a frame. the longer your stem usually means better weight distribution as you can get your weight over the front wheel. pro's are usually 120-140.
as for 100mm --> 110mm stem. You could save your money and just slide the saddle back 1cm on the rail?
and change the knee over spindle? why do that when this should be fixed and then the frame size/stem length/bar height altered to get the correct cockpit length.
and change the knee over spindle?
Obviously, the precision to which you place your bum onto the saddle is superior to mine.
You could save your money and just slide the saddle back 1cm on the rail?
In my experience ,10mm change (from my fit) in saddle position will put me in lower back pain world.
I would play around with the stem length.
Try and borrow some to test it out first if you can.
Sounds like the OP is very aware of all the factors which contribute to bike fit & handling & that you can't really just add a bit here and there to mask an otherwise poor fit.
Anyway, I went from 110->120 on my road bike last year. I found it much better for descending - more stable, better turn in. Probably to do with more weight over the front wheel.
I'm just starting to experiment with 100->110 on my cross bike for road use. It did feel a bit short with 100, but with 100 turn-in steering feels weird on the road.
I've also just seen the pic in your other thread. It does look wrong! Probably a M Giant would be better. I'm a nats under 6ft and with long legs and arms, and shortish torso, I know from experience I sit better on a M Giant.
There's also the question about how you use the bike and what your typically rides are. I train & race & don't like bimbling along, so tend towards aggresive positions. Someone riding 15 mile pootles would prob be set up more like your current bike for higher front end comfort!
Good luck with the fitting... It's taken me years of dicking about with bike fit to appreciate the finer details!
thanks for all so far. CP, yes, I have looked into it in loads of detail (I even have a full size paper drawing, rulers and protractor 
of the 2 cockpit setups, which the shop want me to take with me !) , and if it was mtb related i would probably know the answers. Road riding is not so familiar to me though. Between these 2 threads I have got loads of good advice, so much appreciated to all.
At 46 yrs of age, I'm never going to be a bum up head down racer, but regularly to 50 - 60 mile road rides on my cx bike and will be doing a couple of 100 milers on the new bike this year hopefully
Obviously, the precision to which you place your bum onto the saddle is superior to mine.
that's because i paid for a precision bum fit from a professional, this enabled me to ride 60-100 miles without issue. worth every penny (along with the custom footbeds and cleat shims)
Mudsux, all on the jig and power system used for the fit. If your getting sn extra 80 watts on your TT set up based on position then Id be intrested to see your road bike set up mate! But hey Ho
OP sorry, reckon that change won't be an issue mate!
Another thing to chuck into the equation (I guess) is the reach of your bars.
I prefer to use a long stem (120mm I think) and compact bars that have a reach of about 80mm (or just less) rather than a shorter stem and bars with a long reach. Seems to give me a bit more room for my knees when climbing very steep hills.
It's always hard to do without seeing people in real life on the bike, but you're obviously pretty handy fitness wise. The bars are very high relative to the seat position, and from your other thread it sounds like you've not played with the spacers too much. I'd try dropping the stem a fair bit. I used to ride a 58cm Focus, and after a while of playing ended up taking all spacers out from under the stem. This dropped the bars 20mm. Way comfier, better handling.
I then changed frame to a 56, exact same model. Head tube is 20mm shorter, but I use between 5-10mm spacers. So, compared to my original set up, I'm now about 30-35mm lower at the front. It's made a huge difference!
davidtaylforth +1.
I use compact bars and the longer stem is partially to compensate. I prefer the flat section of bar to be a bit further away than I would achieve with non compact bars and a shorter stem - I'm too squished up.
As cp says,it does take a bit of faffing about to fine tune your position,but you should get a feel for it with the higher mileage.
Post up how you get on at the fitting session
In my experience longer stem, slower steering, and vice versa, as cp said, depends on your type of riding, you seem to have a long torso, so smaller frame and longer stem seems to make sense....let us know how you get on.
i paid for a precision bum fit from a professional
it sounds like the professional fitted your bum well
LOL at 80 watts.
Am I in a minority in just having had set ups that seemed reasonable and found them all comfortable? Rather than spending £££ and many hours refining it to the mm?
My theoretical perfect fit is probably 58, in recent times I've used 60 and 56, I've just altered saddle position and stem length to fit, no issues on any of them.
cheers all, update will follow this evening. I'd better go do some work now !
Some interesting bits on bike fit in this week's comic, also claims the old 'just behind the kneecap over the pedal axle' is just a myth and other measurements can take priority.
And yeah 80w difference from a standard 5-20mm spacer is BS...
Wookster, either your mate is having a laugh at your expense or he is delusional. 
10 mm can make a huge difference on a road bike. I have a 90 mm stem with 10 degree rise on mine. Bike handles beautifully.
Am I in a minority in just having had set ups that seemed reasonable and found them all comfortable? Rather than spending £££ and many hours refining it to the mm?
Am I in a minority in just having had set ups that seemed reasonable and found them all comfortable? Rather than spending £££ and many hours refining it to the mm?
I used to think not, but the world of single track is a joyous world for the pro-bike fit providers, selling to none pro-riders. My three road bikes are 54, 55 and 56cm frames and all three see me race and ride ton plus rides with no 'fit' issues, or impact in times/ performance. I agree small tweaks can make a big difference to your posistion, but I don't find it a difficult process to work that out for myself. But if folk feel they benefit from a fitting, then go for it, it it gets people riding happier then it's all good.
But this weekend I will be attempting to find the magic 80 watt spacer...........cough..
Mudsux if you read some of the marketing stuff a speed play pedal has a simlar reduction in drag as a aero front wheel! Either way you're average sportive rider won't generate the speeds for and real savings from aero kit at what a min if 25mph ish A proper fitting bike will make more difference than aero kit.
Either way my work is done I've spawned a BS if the week thread.......and enraged many!! 
80-watt spacer
Hmm Im going to get some made up for my ebay store, and stock those energising wristbands too.
ok, update time. 2 and a bit hours bike fit session - extremely useful and informative. I ended up with the M frame, rather than the M/L and with the stem at 110mm, rather than the stock 100.
The finished article :
well chuffed
That looks much better proportioned and how a road bike should look. Enjoy.
GJP - yes, I think it looks better, and it feels better position wise (or at least on the turbo in LBS)
Looks grand, enjoy
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