Need an education on frame angles (Retul fitting related)

Raffles

So I was at a Retul fitting session on tuesday which confirmed my worst fears that Im a bit of a nightmare when it comes to bike fitting :roll: , Im just over 5 ft 8 inches and have a 30 inch inseam with short arms. The fitter was getting a bit frustrated as the fitting was far from a stroll in the park and we discussed how a custom frame might be the answer. It appears that a frame with a toptube in the 535mm ballpark mated with a headtube in the 165mm area that has room for about 25mm of spacers would get me closer to a perfect fit. Trouble is, those specs are custom frame build and that means a lot of money What I need is what Id call a short and tall frame, short toptube and tall headtube.

Where I need a bit of education is in frame angles:

Would I be right in saying that a relaxed headtube angle would be 72 degrees ?

Would a 73 degree seattube be a good mix with a 72 degree headtube to improve comfort and lessen reach ?

In terms of relaxed fit, what is the best angle for a seattube ?

What is the best headtube + seattube combination for a really comfortable bike that reduces reach , takes strain off back and allows the use of a longer stem, say 11cm - 12cm ?

A lot of questions, but Id appreciate some guidance from those who know a bit about these things. I see the size 54 specialized secteur has 72 degree headtube and 73 degree seattube , but a toptube of 548mm and that seems a tad long , or would the slacker headtube have a reach shortening effect ?

Bike fitting is supposed to be straight forward............but I appear to be the odd one out :roll:

Grill

Ermmm.. 5'8" with short arms tells me you need shorter than a 535mm top tube, and as far as the Secteur is concerned, a 54 is too big (I'm way bigger than you and would ride that size).

What exactly was the fitter get frustrated at? Surely he should be able to stick you on something around a 52 and sort your position with the proper seatpost and stem.

Which shop?

Raffles

Grill wrote:

Ermmm.. 5'8" with short arms tells me you need shorter than a 535mm top tube, and as far as the Secteur is concerned, a 54 is too big (I'm way bigger than you and would ride that size).

What exactly was the fitter get frustrated at? Surely he should be able to stick you on something around a 52 and sort your position with the proper seatpost and stem.

Which shop?

Specialized list the size range for a 54 secteur as 5 ft 6 to 5 ft 9 and a size 52 would have a headtube that is far too low ..........see my conundrum ?

ShutUpLegs

Did he measure your arm span?

Raffles

ShutUpLegs wrote:

Did he measure your arm span?

With my short arms and legs I do have a long torso and this combination is just driving me to distraction when it comes to bike fitting................im literally considering having a medieval torturer put me on the rack.

letap73

Have you tried the Cannondale Synapse?

ShutUpLegs

How much shorter is your arm span than your height?

Raffles

letap73 wrote:

Have you tried the Cannondale Synapse?

tried one of those and it weighed a ton , just wasnt for me.

Grill

Raffles wrote:

Grill wrote:

Ermmm.. 5'8" with short arms tells me you need shorter than a 535mm top tube, and as far as the Secteur is concerned, a 54 is too big (I'm way bigger than you and would ride that size).

What exactly was the fitter get frustrated at? Surely he should be able to stick you on something around a 52 and sort your position with the proper seatpost and stem.

Which shop?

Specialized list the size range for a 54 secteur as 5 ft 6 to 5 ft 9 and a size 52 would have a headtube that is far too low ..........see my conundrum ?

No I don't. If the bike geometry is wrong for you then you need to look at a different bike. Also, just because a manufacturer makes sizing recommendations doesn't make them correct. There's only a 20mm difference between headtubes (on a bike with seriously upright geometry) and that's easily sorted with spacers and the correct stem angle. Who is this fitter?

letap73

Raffles wrote:

letap73 wrote:

Have you tried the Cannondale Synapse?

tried one of those and it weighed a ton , just wasnt for me.

The carbon version perhaps - it does have a shorter top tube/longer head tube
This with 6 months interest free credit:

http://www.paulscycles.co.uk/products.p ... 7b0s6p4510

jezzpalmer

Check the geomety of the Focus Izalco Ergoride, off the top of my head a small is 535 with 165 head tube and a bunch of spacers, 30mm iirc.

Wiggle have some good deals at the min on 2012 models.
http://www.wiggle.co.uk/?s=ergoride

EDIT:
Small is 532 with head tube of 150.
Medium is 537 with headtube of 165.

Go here and click the geometry tab.
http://www.focus-bikes.com/int/en/bikes ... -30-5.html

rolf_f

What brands did the shop sell? Ultimately, some brands don't have much geometric variety. I went to Epic Cycles expecting to get a Bianchi but they are too long for me. So I then upped my budget for a custom Viner (actually cheap for custom but still more money!) - unfortunately, Viner had problems so that was the end of that. In the end, the only frames that Epic could find to fit in their stock was a Look and a Scott. If I hadn't been up for one of those I'd have taken my measurements elsewhere.

Basically, you might need a custom frame but it might just be a case of finding a shop knowledgeable enough to find the ready made frame that fits you. And you need to be open minded to whatever that brand might be.

MichaelW

In the olden days, you could only get one style of seatpost so you had to adjust the set-tube angle to get a greater range. Today we have posts with inline clamps and extended layback. Part of the original Giant TCR deal was that they offered an extensive range of seatposts.
Once you have your saddle layback sorted, you can look for reach. Again, you can pick a stem with the length and rise to fit. Total reach is a combination of TT and stem length (+ bar style) and there is no single correct solution. People use quite a wide variety (short TT/long stem and visa versa) , and as long as you don't go to extremes of stem, the handling remains acceptable. On most medium frames, a stem of 8-12cm works.
Endurance style bikes tend to have a higher top tube than race-style roadbikes.
The headtube angle is usually used to adjust steering response but on small frames it is hacked to provide foot clearance for extra large 700c wheels. It is very rare for custom builder to use HT angle as part of the fitting equation for medium riders.

I suggest you get out some square graph paper, plot your points of contact (pedal, saddle, bars) and see how they join up in a variety of ways.

What is the issue you are having with stock medium bikes.

meesterbond

I thought that Retul were developing a database of bike frames so that they could help identify the best / closest fit for the measurements provided. I don't know how advanced it is, but my fitter mentioned it when I was done 7 or 8 months ago.

Might be worth dropping them a note and seeing whether they can help.

jotko

Grill wrote:

Ermmm.. 5'8" with short arms tells me you need shorter than a 535mm top tube, and as far as the Secteur is concerned, a 54 is too big (I'm way bigger than you and would ride that size).

What exactly was the fitter get frustrated at? Surely he should be able to stick you on something around a 52 and sort your position with the proper seatpost and stem.

A 54 might be fine. To use the example of the secteur, there is usually only 11mm difference in ETT between a 54 and 52, well in the range of stem adjustment.

There is 20mm of headtube difference between the two though

I would rather have a one size shorter stem on a 54 frame rather than a huge stack of spacers on a 52 to get the bars the right height.

In fact that is exactly my set up - I have a 545 top tube and a 90mm stem, I am 5'7 with fairly longish arms (+ive ape index). My bike is very comfy, my back cannot handle a massive seat to bar drop so I find this set up perfect.

Grill

Different strokes. There's no way I'd use less than 100mm stem on a road bike (and even then I don't truly fell comfortable until 110mm+).

jezzpalmer

meesterbond wrote:

I thought that Retul were developing a database of bike frames so that they could help identify the best / closest fit for the measurements provided. I don't know how advanced it is, but my fitter mentioned it when I was done 7 or 8 months ago.

Might be worth dropping them a note and seeing whether they can help.

It's getting better, it relies on manufacturers subscribing to it.
You also have to pay to be 'matched'.

rolf_f

Grill wrote:

Different strokes. There's no way I'd use less than 100mm stem on a road bike (and even then I don't truly fell comfortable until 110mm+).

That's like saying "There's no way I'd ride a bike that didn't fit me!" For me, a 90mm stem is fine. Actually, I think worrying about short stems is unneccessary anyway - you just get used to it. I suspect I'd find a longer stem would feel very sluggish - but then I'd get used to it and be fine before the back-ache kicked in

Grill

Rolf F wrote:

Grill wrote:

Different strokes. There's no way I'd use less than 100mm stem on a road bike (and even then I don't truly fell comfortable until 110mm+).

That's like saying "There's no way I'd ride a bike that didn't fit me!" For me, a 90mm stem is fine. Actually, I think worrying about short stems is unneccessary anyway - you just get used to it. I suspect I'd find a longer stem would feel very sluggish - but then I'd get used to it and be fine before the back-ache kicked in

Surely there's a reason you don't see short stems in the peloton...

jezzpalmer

Grill wrote:

Rolf F wrote:

Grill wrote:

Different strokes. There's no way I'd use less than 100mm stem on a road bike (and even then I don't truly fell comfortable until 110mm+).

That's like saying "There's no way I'd ride a bike that didn't fit me!" For me, a 90mm stem is fine. Actually, I think worrying about short stems is unneccessary anyway - you just get used to it. I suspect I'd find a longer stem would feel very sluggish - but then I'd get used to it and be fine before the back-ache kicked in

Surely there's a reason you don't see short stems in the peloton...

I'm speculating, but pro tiders tend to be a lot more flexible and ride far more aggressive setups, meaning small frame (smaller than you're average joe would be fitted to) and a long stem & high seatpost.

jotko

Grill wrote:

Rolf F wrote:

Grill wrote:

Different strokes. There's no way I'd use less than 100mm stem on a road bike (and even then I don't truly fell comfortable until 110mm+).

That's like saying "There's no way I'd ride a bike that didn't fit me!" For me, a 90mm stem is fine. Actually, I think worrying about short stems is unneccessary anyway - you just get used to it. I suspect I'd find a longer stem would feel very sluggish - but then I'd get used to it and be fine before the back-ache kicked in

Surely there's a reason you don't see short stems in the peloton...

Well, here is a description of Phillip Gilbert's set up from the main site

- http://www.bikeradar.com/road/gear/arti ... r01-36238/

Another common pro trend perpetuated here is the undersized frame. Despite standing at 1.83m (6ft) tall, Gilbert rides a rather diminutive 50cm frame with a 535mm effective top tube length – something no fitter in their right mind would do for a typical cyclist of the same height.

As usual, though, it's all about head tube length for these guys. In this case, the top of Gilbert's bar sits more than 12cm below the top of his saddle. To get the reach he wants, Gilbert then has to run a 140mm-long stem slammed atop the headset.

Sure, the extreme position looks way cool, and the 'SLAMYOURSTEM' kids would worship the ground you roll on. But let's be realistic here – you're not Philippe Gilbert, and twice-daily Ashtanga yoga sessions and a closet full of Lululemon probably aren't going to get you there, either.

Bascially a pro is trying to achieve the exact opposite to most road bike users who just want to be comfy over long distances - I would be in traction for months if I attempted to ride the drops with that sort of saddle to bar drop

Grill

Well who knew, I fit like a pro. Now I just have to figure out how to ride like one!

rolf_f

Grill wrote:

Rolf F wrote:

Grill wrote:

Different strokes. There's no way I'd use less than 100mm stem on a road bike (and even then I don't truly fell comfortable until 110mm+).

That's like saying "There's no way I'd ride a bike that didn't fit me!" For me, a 90mm stem is fine. Actually, I think worrying about short stems is unneccessary anyway - you just get used to it. I suspect I'd find a longer stem would feel very sluggish - but then I'd get used to it and be fine before the back-ache kicked in

Surely there's a reason you don't see short stems in the peloton...

The 'Pros do or don't do it' argument almost never works because they don't ride like we do. They can have tubs on delicate carbon rims because they get instant wheel changes. They can run higher gears because the group mass of the peloton keeps them at a higher speed. They can have more aggressive setups because they are usually in the saddle for a shorter time than we are. A piece of kit that saves them a fraction of a second can mean the difference between winning or losing whereas for us it just means we eat our cake a fraction of a second later etc etc.

As for stems - I'd be surprised if there are no short stems in the peloton. It's down to your shape. I'd be over stretched with a longer stem. The perfect bike fit is impossible for me because if I had a shorter frame and a longer stem to accomodate, my knees would hit the bars when out of the saddle. But, yes, ideally in a peloton you would have a longer stem because you would want slightly more stable steering because you riding very closely within a huge bunch of people. Again, that is an issue for the pros but not most of us.

Grill

How would your knees hit? If the toptube is 10mm shorter and the stem is 10mm longer your effective reach should stay the same.

rolf_f

Grill wrote:

How would your knees hit? If the toptube is 10mm shorter and the stem is 10mm longer your effective reach should stay the same.

Urrrgh! Good point! The correct argument in my case was that there aren't any shorter top tubes! If I went shorter, I'd have a lower headtube and all sorts of other fit problems. That said, the bars do move further back for a given change in direction with a longer stem so if you are standing, the clearance will be reduced as you push from side to side.

Grill

That's entirely dependent on the stem angle...

gloomyandy

Going back to the original question. Some other things to check when looking at geometry...
1. Check the reach of the bike (bb to headtube, horizontal) as the effective top tube length may not be a good guide to how stretched you will be due to different seat angles. Smaller bikes often have steeper seat tube angles which makes the effective top tube length shorter, but if you have to have your saddle pushed way back to get your knee position correct then the reach may not be any shorter.
2. the head tube angle also impacts on the height of the bars (in effect it changes the stem angle), so a small frame with a slack head tube angle may end up with a higher bar position then a larger frame with a longer head tube and steeper head tube angle. Hard to describe but there are web sites that let you play around with all of this to compare different stems etc.
3. If you are going to get a bike with a slacker head tube, you may also want to get a fork with a different offset/rake, to compensate.

colsoop

Whats the bike for ?

giropaul

A size 52 Specialized Roubaix has a 537 virtual top tube and a 145mm head. With a headset cone it would only need 15mm or so of stackers (or a slightly inclined stem).

rolf_f

Grill wrote:

That's entirely dependent on the stem angle...

Not entirely - and stem angle is really only a function of how you want to address the issue of the height gap between the top of the head tube and the handlebars.

Raffles

Im seriously considering having a custom frame made and having a dynamic bike fit carried out on a jig with moveable toptube and headtube to ascertain the bike fit that fits me like a glove. It will cost a bit more , but at least it will be tailored just for me and my body shape......................getting it past the wife, thats the hard bit.