Does Geometry matter here ?

Rowery

Hello,

I need help, I'm about to make an investment in a new carbon bike, I don't want the most aggressive set up but I'm also not really buying into the whole sportive bike thing, I think the differences in Geometry and head tube lengths etc might be negligible but I’m not sure, I only have the one bike and haven’t really ridden any others.

I do want something comfortable that will put more of the weight on my backside as opposed to my wrists. The bike I really like out of the three in the table below is the Principia, I’m a bit concerned about buying it on the net but I can send them my measurements to try to get the set up right.

Any advice is welcome, do you think there is any real difference in these set ups? Thanks

Lumen

I have a lot of bike fit resources (books, DVDs) including some good stuff by Steve Hogg, a proponent of rearward seat position. His view is that if you don't have the "structural fitness" (i.e. flexibility and core strength) to support an aggressive position, you should move the seating position rearwards to move weight off your hands. He calls this a "rehabilitative" position, because it's not something you would necessarily use on a permanent basis.

I used this approach for a few months when I was new to cycling, and it helped a lot with shoulder and wrist pain. Now I am fitter I have moved the saddle forward to a more neutral position.

In my view it is important to choose a bike for which you are in the mid-range fit wise, i.e. with a standard fit you have a normal length stem (e.g. 110mm) and a couple of cm of spacers. You can then cut the steerer tall and ease off the position to start with (move saddle back, handlebars up, shorten stem) then progressively adapt the position as time goes in.

For instance, I am about right for a 565mm top tube. My current bike has a 560mm tt and 130mm stem (shortly to be replaced with a 120mm stem). Some bikes I have considered have two adjacent sizes, one with 555mm and the next with 575mm. Although I could probably adjust either to fit by tweaking stem length and saddle position, I would not avoid this as it gives no room to manouvre.

I have been told that most bikes are now designed to be used with 3cm of spacers, i.e. the headtube is deliberately too short for many prospective owners, and they rely on overbuilt forks to take the strain. Personally I would rather have a tall head tube and a 5mm spacer that a short headtube and 30mm of spacers, and if that means I'd end up with a "sportive bike" then so be it.

Not sure if this helps.

Lumen

Do all those bikes use integrated headsets?

The Ace looks very tall.

Rowery

Hi Lumen, Thanks for the above, I think they are all intergrated headsets, I'm not so sure about the Principia, I also though the Ace was very tall. I'm heading up to Slane Cycles on Friday to take a look at the Bianchi infinito, I have had my heart set on that bike for a while until a fiend pointed me towrds the Prinipia, I'm worried that it will be too aggressive, I have a bit of a problem with a shoulder injury that is permanent so I kind of want something that will give me a good riding position for long rides.

Lumen

Rowery wrote: »

Hi Lumen, Thanks for the above, I think they are all intergrated headsets, I'm not so sure about the Principia, I also though the Ace was very tall. I'm heading up to Slane Cycles on Friday to take a look at the Bianchi infinito, I have had my heart set on that bike for a while until a fiend pointed me towrds the Prinipia, I'm worried that it will be too aggressive, I have a bit of a problem with a shoulder injury that is permanent so I kind of want something that will give me a good riding position for long rides.

According to the marketing, although the Infinito has the geometry of a sportive bike it can be/is being succesfully raced by Pro Tour teams. I'm not sure I'm entirely convinced by that.

Also, I've read reports in discussions about another bike that some Bianchis can be a bit flexy (the 928SL was mentioned).

The problem with buying bikes is that 90% of the "information" is complete bull.

All that aside, I wouldn't mind an Infinito myself, although it would have to be in Celeste/White not the Red/White of some of the press bikes.

The Infinito is not exactly cheap though, and IMO the styling demands Campag or SRAM, although it seems many of the built bikes come with Ultegra.

petethedrummer

I've been looking at a Carbon sportive bikes myself and the ACE does indeed seem very tall in the headtube region. But then in any of the pictures of the ACE there seems to be less room left for spacers, so maybe it all evens out.

horizon26

Lumen wrote: »

I have a lot of bike fit resources (books, DVDs) including some good stuff by Steve Hogg, a proponent of rearward seat position. His view is that if you don't have the "structural fitness" (i.e. flexibility and core strength) to support an aggressive position, you should move the seating position rearwards to move weight off your hands. He calls this a "rehabilitative" position, because it's not something you would necessarily use on a permanent basis.

I used this approach for a few months when I was new to cycling, and it helped a lot with shoulder and wrist pain. Now I am fitter I have moved the saddle forward to a more neutral position.

In my view it is important to choose a bike for which you are in the mid-range fit wise, i.e. with a standard fit you have a normal length stem (e.g. 110mm) and a couple of cm of spacers. You can then cut the steerer tall and ease off the position to start with (move saddle back, handlebars up, shorten stem) then progressively adapt the position as time goes in.

For instance, I am about right for a 565mm top tube. My current bike has a 560mm tt and 130mm stem (shortly to be replaced with a 120mm stem). Some bikes I have considered have two adjacent sizes, one with 555mm and the next with 575mm. Although I could probably adjust either to fit by tweaking stem length and saddle position, I would not avoid this as it gives no room to manouvre.

I have been told that most bikes are now designed to be used with 3cm of spacers, i.e. the headtube is deliberately too short for many prospective owners, and they rely on overbuilt forks to take the strain. Personally I would rather have a tall head tube and a 5mm spacer that a short headtube and 30mm of spacers, and if that means I'd end up with a "sportive bike" then so be it.

Not sure if this helps.

What is an over built fork?I have a focus cayo the head tube is 135 and I can only fit 3 spacer's.If I could fit another few spacer's and rise my headtube height my bike would be a perfect fit.I am not that flexable especially after the christmas i had!I could flip my stem but it looks terrible as my stem is 130!!

blorg

horizon26 wrote: »

What is an over built fork?I have a focus cayo the head tube is 135 and I can only fit 3 spacer's.If I could fit another few spacer's and rise my headtube height my bike would be a perfect fit.I am not that flexable especially after the christmas i had!I could flip my stem but it looks terrible as my stem is 130!!

He is suggesting that forks need to be overly heavy to cope with the protrusion out of the headtube. I think this is academic myself as all forks even the lightest ones are designed to work with at least a reasonable number of spacers over the head tube, it's not as if you can reasonably get a lighter one that will only work with no spacers. So it is more a question of your aesthetic niggles.

As for your current bike, christ, flip the stem already and get comfortable.

horizon26

Good advice blorg,you are right of coarse thanks.:):)

Lumen

blorg wrote: »

He is suggesting that forks need to be overly heavy to cope with the protrusion out of the headtube. I think this is academic myself as all forks even the lightest ones are designed to work with at least a reasonable number of spacers over the head tube, it's not as if you can reasonably get a lighter one that will only work with no spacers. So it is more a question of your aesthetic niggles.

My (badly made) point was just that since the forks are designed to cope with 3cm of spacers, frames are designed with the expectation that spacers are used, so it is not necessary to buy a bike with a sufficiently long head tube to minimize the spacers with the idea that the bike was designed to work best that way.

edit: I'm not even sure what point I'm making. duuuh.

blorg

Lumen wrote: »

My (badly made) point was just that since the forks are designed to cope with 3cm of spacers, frames are designed with the expectation that spacers are used, so it is not necessary to buy a bike with a sufficiently long head tube to minimize the spacers with the idea that the bike was designed to work best that way.

Frames designed that way also give flexibility to change position, allowing you to lower/raise it as you develop flexibility or change your front end or whatever. I am 15mm down on my Litespeed from when I first started and have all the spacers gone entirely on my Bowery. The Litespeed will probably follow to be honest. My tourer I started with around 30mm excess on top and had it finally cut only after I had ridden it for a few hundred km and knew I wouldn't want to go higher. The track bike I am trying to TT on I am currently midway on the steerer with 23mm below and 20mm above. I had it slammed right down but was finding that impossible in the aero bars.

One of the main advantages of the Aheadset system is that it is so easy to change positions like this.