Replies to This Discussion

Permalink Reply by The Grizz on April 2, 2014 at 6:04am

I also prefer horizontal top tubes, but I'm the vintage collector type. I'm a small dude. I am built like a hobbit. It's hard for me to find bikes that fit me - even with sloping tubes. I ride about a 42cm frame, & most manufacturers don't even make one smaller than 50/52. I had a Surly Cross Check for touring, which fit me great, but half my foot overlapped the 700c wheel. Sold it. Built up a vintage frame with 26" wheels, which suit me much better. Long Haul Trucker could've worked, but I wanted something with more character. One of my bikes is a small frame with 700c on rear & 24" on the front (for toe clearance). It has a short fork & a long head tube to make the geometry horizontal. It's really fast, nimble, & pretty much awesome (see pic).

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Permalink Reply by Robert Underwood on April 2, 2014 at 6:38am

According to Wikipedia, (and rocket scientists), "Most cyclo-cross frames have a non-compact (flat or near-flat top tube) frame design for easier shouldering." 

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Permalink Reply by Lanterne Rouge on April 2, 2014 at 2:55pm

Now that I think about what I wrote, I'm not comparing apples to apples. When I owned all three modern, compact frames (52cm & 54 cm) I was fit much more aggressively for that 'pro look' fit. Now that I'm riding a 58cm traditional frame, I've got maybe 2-3 fingers of seat post showing and my quill down a bit. It's a lot different than having a forearm of seat post and a 110mm stem.

Hey! Bike Shop Guy said:

This is just completely wrong information.  

Bikes with sloping top tubes are usually sized by effective seat tube or top tube length; if you ride a 56 in a horizontal top tube that should size out to a 56 in a compact geometry frame.  You may experience some (or a lot depending on the manufacturers) size variation between manufactures but if you are seeing a size difference of that much you are not properly fit on one end of the spectrum.

Lanterne Rouge said:

Sizing is much different on sloping top tubes as well. Whereas I ride a 57-58 cm on a traditional frame, I have rode 52-54 cm on a compact frame, with no issues whatsoever. 

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Permalink Reply by Hey! Bike Shop Guy on April 2, 2014 at 4:12pm

If you have that little seat post showing I would say that you are on a little bit too big of a frame as well and/or using some outdated fit theory but if you're comfortable on the bike run with it.

Lanterne Rouge said:

Now that I think about what I wrote, I'm not comparing apples to apples. When I owned all three modern, compact frames (52cm & 54 cm) I was fit much more aggressively for that 'pro look' fit. Now that I'm riding a 58cm traditional frame, I've got maybe 2-3 fingers of seat post showing and my quill down a bit. It's a lot different than having a forearm of seat post and a 110mm stem.

Hey! Bike Shop Guy said:

This is just completely wrong information.  

Bikes with sloping top tubes are usually sized by effective seat tube or top tube length; if you ride a 56 in a horizontal top tube that should size out to a 56 in a compact geometry frame.  You may experience some (or a lot depending on the manufacturers) size variation between manufactures but if you are seeing a size difference of that much you are not properly fit on one end of the spectrum.

Lanterne Rouge said:

Sizing is much different on sloping top tubes as well. Whereas I ride a 57-58 cm on a traditional frame, I have rode 52-54 cm on a compact frame, with no issues whatsoever. 

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Permalink Reply by Hey! Bike Shop Guy on April 2, 2014 at 4:15pm

Both of those bikes come in normal sizing increments.  

There are legit reasons for the sloping top tube like head tube height and standover; stop trying to; just because you don't like it does not mean there are not real reasons for it.

Jeff Schneider said:

My 520 doesn't have a sloping top tube, and I don't care about the leg over argument, since I always mount by leg over saddle from behind anyway (but I guess others might do otherwise).  And these touring bikes you are thinking of don't have a lot of slope in the top tube anyway, so it probably makes no difference at all (except for needing fewer frame sizes to get adequate stand over for all riders).  So, I'm not saying it's bad, just that it makes no difference at all for most purposes (so you might as well get what you think looks good).

Hey! Bike Shop Guy said:

Slopping top tubes are nice on loaded touring bikes because they make it easier to get a leg over a loaded bike.  The Trek 520 and Soma Saga (and some tour bikes I can't think of at this second) have slopping top tubes and fit racks quite well.

You have a preference which is based on looks, and that's fine I prefer a traditional top tube appearance wise myself., but stop trying to justify when there are legit performance reasons for the slopping top tube.

Jeff Schneider said:

Of course, the needs of racers, tourists and randonneurs might be different.  As a tourist riding at a moderate pace with some gear, I really don't care what frame geometry a racer uses.  A compact frame is awkward for fitting racks and carrying gear IMO.

I can believe the stiffness argument (to a point), but I also know that even racing has fashions, like tire width going mostly to 23mm then mostly back to 25mm...and of course, even the desirability of frame stiffness beyond a certain point is questioned (see BQ).

As for bikes sold to recreational riders, I am willing to bet that superior stiffness is not the main reason for the compact frame.  I think it's much more likely that it's used to make fitting riders of different sizes easier (which is not a bad thing).  I'm sure you are right that the threadless stem encourages compact geometry, too.

So, while compact geometry may have benefits for some, it may have none (or even be disadvantageous) for others.  For most, it probably doesn't matter either way.

Hey! Bike Shop Guy said:

There is just so much bad info here I don't even know where to start...

Slopping top tubes and compact geometry have several reasons, but the biggest one is stiffness of the frame.  Smaller triangles and shorter tubes translate into less flex in a frame which means there is less waste turning power from the rider into forward motion.  I don't really know what proof of this some of you are looking for because it seems like pretty common sense to me...

Fit does have a little to do with it but mostly because the taller head tube allows for a higher bar position without a super tall stem of having the steer tube being super long which is not only not vert stiff but hard on headsets.  It's easier to be able to get that high bar position on a bike with a quill stem than it is on a threadless stem which is one of the reasons top tubes started to slope more on newer bikes.

As for some kind of cost slashing conspiracy with the manufactures that is just pure nonsense.  

If compact geometry allowed manufactures to get the proper fit with fewer frame sizes why do they all still make frames in 2cm increments?  Yes, cheap hybrids and low end bikes often come in fewer sizes but that has less to do with the manufactures trying to save money and more to do with those bikes, and customers, not being as fit sensitive

If there was a benifit to traditional horizontal top tubes do you think all the pros would be riding compact frames?

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Permalink Reply by Reba 4.0 mi on April 2, 2014 at 4:53pm

I don't think they look cool and I'll never have another bike with a sloping top tube.

As a short person (5'1-ish) my next bike will have a straight top tube simply because it's far easier to carry it up and down the stairs. I need every mm I can get to clear the wheels from the ground since my arms are so short! Yes, I notice the difference between my vintage Fuji mountain bike from the 80s (smaller wheels/straight tube) and my new Torker (larger wheels/sloping tube).

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