Compact Frames...
- Thread starter Unbelievably
- Start date
Thanks for the link...
However,
the way it was written almost make it sound as though
"standard" horizontal frames are obsolete......
How does one take sizing into consideration?
For example,
If I was to normally be fit for a 580mm frame.
Would a 520mm C/F be suffice?
However,
the way it was written almost make it sound as though
"standard" horizontal frames are obsolete...
...How does one take sizing into consideration?
For example,
If I was to normally be fit for a 580mm frame.
Would a 520mm C/F be suffice?
Use the table half way down this page: http://www.giant-bicycles.com/au/050.000.000/050.750.100.asp
580mm top tube = Large.
580mm top tube = Large.
Many builders want to convince us that 'standard' geometries are obsolete, because with compact frames they can usually get away with three standard sizes (S, M, L) and you then have to fit the dang thing to your measurements with seatposts and stems. It is a great deal for them.
The idea is that you get a more rigid frame (although you have to counterbalance this with the fact that you lose rigidity with the longish seat posts that a lot of people are then forced to ride).
Go with what you like and what fits you better. But absolutely do not believe the hype that compact frames are the only way to go. That is... somewhat untrue!
The idea is that you get a more rigid frame (although you have to counterbalance this with the fact that you lose rigidity with the longish seat posts that a lot of people are then forced to ride).
Go with what you like and what fits you better. But absolutely do not believe the hype that compact frames are the only way to go. That is... somewhat untrue!
Pete is right, the frames are usually stiffer. Except Giants alu TCRs are extremely flexy due to the weight, which is miniscule.
They are usually lighter too
The long seatposts generally counter alot of the frame weight loss, the flex makes it more inefficient, and no matter what, the fit will never be as perfect as what it could be with a traditional frame which has the geometry you want. Compact frames are like diets, they make you lighter, but they are hard to live with and never as fun as not being on one. A well fitted bike (which is very hard to achieve in a compact frame) is like being bestowed with the gifts of a cycler. You can do everything with much less trepidation.
Sorry for my terrible analogies
They are usually lighter too
The long seatposts generally counter alot of the frame weight loss, the flex makes it more inefficient, and no matter what, the fit will never be as perfect as what it could be with a traditional frame which has the geometry you want. Compact frames are like diets, they make you lighter, but they are hard to live with and never as fun as not being on one. A well fitted bike (which is very hard to achieve in a compact frame) is like being bestowed with the gifts of a cycler. You can do everything with much less trepidation.
Sorry for my terrible analogies
Compact frames exist to save the manufacturer and the bike shop money at the expense of giving the customer a sub-optimal fit. The reasons given to justify them are marketing ******** that was devised after the business decided they could help their bottom line by screwing the customer.
Until you get into high end frames, where compact geometry is more for fashion and compact frames are made in the same size increments as traditional geometry frames, you only have a few choices in frame sizes. It can be as little as three sizes. Sometimes it is five, but that usually breaks down to three sizes for most people plus a huge size for very tall people and a tiny size for very small people; so the end result is you still only have three sizes if you fall into the more normal range of height.
A few lucky people will fit one of the available sizes perfectly. Everyone else will fall in between sizes and is expected to compensate by making changes to the stem and seat post. Most people end up with a frame that does not fit.
The stiffness issue is bogus. Back in the 70s and 80s frame stiffness was an issue because most frames were made with thin tubing made of steel or made with the same dimensions as steel tubes. Nowdays pretty much all frames use oversized tubes and if a frame has some flex it is because the designer wanted it that way. For a cyclist of typical weight worrying about losses due to frame flex is like worrying about losses due to drive train friction. If you can flex a frame enough to cause derailleur rub or auto shifting then you are either very heavy or the frame is ****. If you are very heavy the answer is not the minor extra stiffness that can be gained by dropping the seat cluster a few inches; it is buying a stiff frame made with large diameter tubes like a Cannondale.
Also compact frames are fugly.
Until you get into high end frames, where compact geometry is more for fashion and compact frames are made in the same size increments as traditional geometry frames, you only have a few choices in frame sizes. It can be as little as three sizes. Sometimes it is five, but that usually breaks down to three sizes for most people plus a huge size for very tall people and a tiny size for very small people; so the end result is you still only have three sizes if you fall into the more normal range of height.
A few lucky people will fit one of the available sizes perfectly. Everyone else will fall in between sizes and is expected to compensate by making changes to the stem and seat post. Most people end up with a frame that does not fit.
The stiffness issue is bogus. Back in the 70s and 80s frame stiffness was an issue because most frames were made with thin tubing made of steel or made with the same dimensions as steel tubes. Nowdays pretty much all frames use oversized tubes and if a frame has some flex it is because the designer wanted it that way. For a cyclist of typical weight worrying about losses due to frame flex is like worrying about losses due to drive train friction. If you can flex a frame enough to cause derailleur rub or auto shifting then you are either very heavy or the frame is ****. If you are very heavy the answer is not the minor extra stiffness that can be gained by dropping the seat cluster a few inches; it is buying a stiff frame made with large diameter tubes like a Cannondale.
Also compact frames are fugly.
I rode a cannondale '92 r800 for years up and down the steepies of Southeastern Pennsylvania. I picked up a Litespeed Sienna in the early summer (compact geometry) and from my persepective (even though the weight of the bike is comprable), the Litespeed climbs better than the old Dale. My buddy has a Tuscany (traditional geometry) of the same size and recent vintage so we switched back and forth during a hill circuit (and the comparision was even closer) the compact geometry felt better. On very steep hills 8degrees or more, and when you started standing, the compact geometry made you feel like you were directly over the rear wheel, and it was easier to climb in that position.Bro Deal said:
Yeah, all this is subjective and it probably is BS but both me and my buddy, who have both been riding traditional road bikes for almost 20 years, the Sienna is a better climber. (And my buddy with the Tuscany was just as skeptical initially). My geuss, again subjective, is that the longer wheelbase and traditional geometry of the Tuscany would be better on a century, but the Sienna just feels faster and more responsive on a climb.
Don't be a hater. call your LBS and ask to test ride two comparable bikes, one with traditional geometry and one with compact and take them out on a similar route. If you have a buddy of similar size, switch off and on for a closer comparision. See what you think. I can only speak for the Litespeed models.
At the end of the day, 99% of all this is subjective and has to do with what you like riding. If you are in SE PA ever, I'll hook up and race you up some hills and we will switch off. From my perspective, the compact is a better climber. I have no stake in it the outcome.
The problem with that guess is that the Tuscany has a _shorter_ wheelbase than the Sienna. It comes from a front center that is roughly half a centimeter longer in Litespeed's compact geometry. The seat tube angles and chain stay lengths are equivalent for similar sizes of trad and compact Litespeed frames. The Tuscany and Sienna may feel different when climbing, but that has exactly zip to do with whether or not they are compact. Litespeed could have built the Tuscany with the same geometry as the Sienna.kopride said:
kopride said:
Gearing is a whole different story. Damn, I hate running out of gears on a climb! Back to geometry; if you compare a compact geometry bike with a traditional geometry bike and assume all angles (seattube, headtube) are equal than in theory the only difference will be the length of the top tube. Now in a miniscule way the top tube is shorter and thus lighter, but everything else being the same you are still in the same position over the cranks regardless of frame geometry. Speaking of the Siena, I have an 2004 size 53, but I also have a traditional geometry 54. The Litespeed does climb very well indeed, but I would attribute that to being a slightly smaller frame.
kopride said:
Frames cannot be fairly compared by "switching bikes" unless they have the same wheels and tires since these affect ride alot. Also geometry can't be compared unless you also have the same bars, crank length, pedals, and other things that subtly affect bike fit.
I don't necessarily dispute that the Siena bicycle as tested climbs "better" than the Tuscany but rather suggest that there are multiple factors that contribute that are independent of the top tube slope.
I've got a custom frame with a semi-sloping top tube. My builder told me the bike would climb like a full-compact design, yet have all the comfort of a traditional bike on century rides. Sounded perfect for the mountain century events, so that's what I ordered
Bro Deal said:Compact frames exist to save the manufacturer and the bike shop money at the expense of giving the customer a sub-optimal fit. The reasons given to justify them are marketing ******** that was devised after the business decided they could help their bottom line by screwing the customer.
Also compact frames are fugly.
Certainly some truth to the "fewer frame sizes" argument, but compact frames also fit a lot of people better than traditional designs ever did. Folks with long torsos and short legs for example, or short arms, or people with hip and back flexibility issues.
There's a zillion horizontal frames out there, and a zillion compact frames, choice is good.
There is no reason why compact frames can't fit as well as traditional frames. As long as the bars, saddle, cranks, and angles match up, the path the tubes take has no effect on sizing.
The fact that there are less sizes is because production has gone away from the made to order systems where your bike was made in the size you selected then shipped to the dealer, to making half a million frames at a time, having stock waiting, and you picking one up off the floor. Mass production and inventory levels demand lower complexity, hence the drop in frame sizes. Most of this efficiency is passed onto the customer in the way of reduced prices (Giants cost less than made to order bikes).
There are still brands out there that offer 10 sizes, and some of those are compact style frames. If you don’t suit one of the huge array of mass produced compact frames, then you have to look at the more expensive options.
Compact frames probably do weight less size for size because the shorter absolute top tube, seat tube, and seat stay lengths are shorter. This would make the bikes a little bit stiffer. However I would expect the overall torsional stiffness may go down due to less division of forces in different directions. Tubing shape can make up for this and we are now seeing more Al and carbon frames with very wide elliptical top tubes for better torsional stiffness while maintaining vertical compliance.
Better climbing is probably due to different chainstay lengths. Compact frames have a tendency to go for short everything. No reason a traditional frame can’t have short chain stays and the same seating layout.
All up I believe the same ride characteristics can be had out of either frame style if you design the tube lengths, shapes and basic handling dimensions the same. I think a compact frame will weigh a little less due to the shorter tubes (which are only then replaced with a comfortable carbon seat post 30-50mm longer.
The fact that there are less sizes is because production has gone away from the made to order systems where your bike was made in the size you selected then shipped to the dealer, to making half a million frames at a time, having stock waiting, and you picking one up off the floor. Mass production and inventory levels demand lower complexity, hence the drop in frame sizes. Most of this efficiency is passed onto the customer in the way of reduced prices (Giants cost less than made to order bikes).
There are still brands out there that offer 10 sizes, and some of those are compact style frames. If you don’t suit one of the huge array of mass produced compact frames, then you have to look at the more expensive options.
Compact frames probably do weight less size for size because the shorter absolute top tube, seat tube, and seat stay lengths are shorter. This would make the bikes a little bit stiffer. However I would expect the overall torsional stiffness may go down due to less division of forces in different directions. Tubing shape can make up for this and we are now seeing more Al and carbon frames with very wide elliptical top tubes for better torsional stiffness while maintaining vertical compliance.
Better climbing is probably due to different chainstay lengths. Compact frames have a tendency to go for short everything. No reason a traditional frame can’t have short chain stays and the same seating layout.
All up I believe the same ride characteristics can be had out of either frame style if you design the tube lengths, shapes and basic handling dimensions the same. I think a compact frame will weigh a little less due to the shorter tubes (which are only then replaced with a comfortable carbon seat post 30-50mm longer.
