Fit question stretched out on the hoods

[hondated]

Just revisited this thread from the beginning and its got me thinking about my bike position again. I thought the trekking bars were ok but after a head wind ride today I came home and put the drops back on.
Well done everyone for sticking with mark over all this time and advising him so well as well.
Your nearly there Mark.

[macaroon]

I have read through some of this and Freeflow's post regarding his fit with Tim Williams sounds right to me.

I think too often people struggle to reach the bars so they automatically think they should move the saddle forward and shorten the stem length, when infact all this does is squash them up into an even shorter space.

Comfort on a road bike is a combination of feeling loose, relaxed and balanced.

Mark1978, it would be useful if you could post a side-on video of you on a trainer, or even just a photo of you riding the bike (taken from the side).

165mm cranks sound like a good idea if you have short legs. It makes it easier to get your leg over the top of the pedal stroke. I have a long inside leg (93.5cm) but I use cranks only 2.5mm long than yours.

You said you've been fitted but now you suffer from back pain? A saddle too low can cause back pain, I've experienced it myself.

I'd start from scratch (mark your current setup with a makrer pen though).

Start with your cleats, Steve Hogg's method works for me. Pedal axle somewhere behind the ball of your foot (5-10mm or so depending on your shoe size). Cleats too far forward can cause knee pain and hot spots/numb feet. If your cleat position is wrong, it's difficult to do the rest.

Saddle height is a tough one, I think the Lemond method is a good starting point. Measure your inside leg (wedge something right up into your crotch ) and go from there.

Once you've got the cleats and the saddle height right, the rest is quite straight forward and can be done on feel whilst out on your bike.

Now, the key (I think) to comfort and a good position on the bike is the ability to rotate your pelvis/hips forward. This takes the load off your back and increases your reach. So instead of sitting upright and trying to stretch your arms to reach the bars, your torso is now rotated forward, taking up much of the distance to your bars. You may have to practive this a bit, and if your saddle is too far forward/stem is too short, then there won't be enough space for you to rotate into. Certain saddle shapes tend to favour a rotated position (curved ones normally like the prologo scratch or san marco regale).

Here's an image to show you what I mean:



And Fabian Cancellara below (there's no way he'd be able to do that if he hadn't rotated forward):



Once you've figured out how to do the above, the saddle setback/stem length conundrum becomes much more easy to work out. It's just a case of finding a weight balance which is comfortable but and makes the bike handle correctly. All you need to do is increase/decrease saddle setback and change stem length to find that balance. I.e. too much saddle setback and you won't have any weight over the front to steer with. Or not enough saddle setback and you'll be bearing too much weight on your hands and arms.

Hope the above helps/.

[Mick F]

Comfort on a road bike is a combination of feeling loose, relaxed and balanced.

Absolutely spot on!

Since reading this thread ........... and many that have gone before ......... I've been examining my position and comfort etc. Luckily, I'm perfectly set up (I believe) but it was more luck than judgement.

When I ride, my weight is spread over three points. Seat, feet and hands - to a greater or lesser degree. I think I ride with a sort of "suspension", with my weight supported in no particular spot. I'm balanced, fluid, and in control. I shift my weight forward or back as the terrain dictates, and shift well back when braking hard. At no time do I have most of my weight on the saddle, so a nice smooth hard one is great.

My motto is, "Man and Machine in Perfect Harmony".

[horizon]

Now, the key (I think) to comfort and a good position on the bike is the ability to rotate your pelvis/hips forward. This takes the load off your back and increases your reach. So instead of sitting upright and trying to stretch your arms to reach the bars, your torso is now rotated forward, taking up much of the distance to your bars. You may have to practive this a bit, and if your saddle is too far forward/stem is too short, then there won't be enough space for you to rotate into.

I tried this on Sunday. I discounted ideas about bringing the bars nearer me and instead rotated forward from the pelvis to get me nearer the bars. This was fine - it was a good, comfortable position and also seemed to transmit power easily to my legs.

I then held precisely the same position on the bike but moved my hands back from the hoods and onto the straight section of the bars (about 7 cm back). My upper back "unwound" slightly and it felt much more comfortable.

So my conclusion was that while I agree with you about rotating the body, the arms still need to be in the right place. Obviously I'm looking at the possibility of rotating even further forward but I'm not sure that that is what other people are asked to do in order to reach the bars comfortably.

But I'm going to continue the experiment anyway.

[Mark1978]

Went for a short ride yesterday, no issues, apart from the chainstay cable stop snapping off and getting lost somewhere down the road, so now it has to go back to Scott for repair, or possibly a replacement frame!

I'm currently riding a 52cm, if they do say it's going to be a frame replacement is it worth asking for the 49cm instead?

This is the geometry: http://dfp2hfrf3mn0u.cloudfront.net/188 ... inal_1.jpg

[531colin]

I can't read your geometry link on this blasted machine.
I thought you had a Madone?

[Mark1978]

I can't read your geometry link on this blasted machine.
I thought you had a Madone?

Nah I changed the frame in June 2013. Below is the comparison apologies for the formatting.

Code: Select all

                52      49   difference
Head tube angle   73   71   2
Headtube length   136   116   20
Toptube length horizontal   530   515   15
Seat tube angle   74.5   75   -0.5
BB Centre to top of seattube   520   490   30
BB Centre to toptube centre   460   430   30
Chainstay length   405   405   0
BB Offset   -67   -67   0
Standover   765   737   28
Wheelbase   980   978   2
Reach   379   376   3
Stack   545   519   26

[531colin]

Doesn't make sense to me.
Smaller bike has 2 deg shallower head angle....this will move the bars closer with the same front centre
Seat angle is only 0.5 deg different, so "reach" and "effective top tube" should be measuring almost the same difference (+/- 0.5 deg)....but one is shown as 15mm different, the other as 3mm different.

[macaroon]

I wouldn't change the frame to a smaller size. There's not much difference in the reach between the two, but the stack is over 25mm less, so you may end up with a lot of stem spacers.

[macaroon]

Doesn't make sense to me.
Smaller bike has 2 deg shallower head angle....this will move the bars closer with the same front centre
Seat angle is only 0.5 deg different, so "reach" and "effective top tube" should be measuring almost the same difference (+/- 0.5 deg)....but one is shown as 15mm different, the other as 3mm different.

Don't forget, the longer headtube on the small decreases the reach measurement and increases the stack measurement.

[Mark1978]

I would hope it would mean I could ride a bike with a decent length stem and a decent amount of seat post showing.

Thinking back, I think every adult bike I've ever owned has been that bit too big for me!

[531colin]

......Don't forget, the longer headtube on the small decreases the reach measurement ..........

Yes, by 5 or 6mm.?** The steeper seat angle on the smaller bike will also reduce the effective top tube, by a small amount.
Chainstays are the same length on both sizes, wheelbase is 2mm. shorter on the smaller bike, so front centre is 2mm shorter.
smaller bike has 2 deg slacker head angle, so the top of the head tube should be maybe 18mm closer to the seat tube. (assuming same fork offset. If they do it properly and use a longer offset with the slacker angle, its a bigger difference)

If the reach is the same within a few millimetres, I agree with Macaroon.....go with the bigger bike, for the higher stack.
But you may need a shop with both sizes in stock, and a man with a plumb line and a tape measure.

**and, just to complicate it, when you space up the smaller size, the same happens.....

[531colin]

Well, heres a funny thing......



from here.....http://www.epic-cycles.co.uk/Scott_Foil.html

Less difference in head angle more difference in reach

[Mark1978]

As long as you're aware that's a Scott Foil, which is not the same as my CR1.

[531colin]

As long as you're aware that's a Scott Foil, which is not the same as my CR1.

Its angles and lengths.
The "foil" table makes sense to me.....on the smaller bike, 1 deg slacker head angle brings the reach down say 9mm. plus 2mm for shorter front centre is 11mm.
take off 5 or 6mm for the higher stack if the bigger bike, so the 5mm difference in reach between the 2 sizes looks right.
15mm difference in ETT comes from 11mm at the front end, and 4mm for 0.5 deg seat tube angle....or thereabouts, all done on the back of an envelope.
(when you space up the bars on the smaller bike, you get the same reduction in reach, of course)

The CR1 table still doesn't make sense, to me at least. Apparently there is a big difference in head angle, which makes hardly any difference at all to the reach......But the reason the designers use a slacker head angle on small bikes is to reduce the reach...