Anti404

So, I've been recently testing several endurance bikes to replace my 58cm CAAD-9 I can no longer comfortably ride. I've been riding mostly 58s with a smattering of 56s. Reviewing the geometry charts, there seems to be very little overall difference in reach (about 5mm, most of the times), with 10-20mm differences in stack and HT length. Does this imply that it would be relatively simple to fit someone who rides a 56cm bike to either a 54 or 58 with things such as stem swaps and seatpost/saddle adjustments?

I ask mostly because I ended up buying, sight unseen, a 58cm Scott Solace - I had test rode the 56cm (they didn't have anything larger in stock) and it felt OK, but after testing the 56 and 58cm models of the Domane, Defy, and Roubaix and preferring the 58cm models, I assumed (after looking at geo. charts) that the 58cm Solace would provide a better fit. Now I'm kind of worried I made the wrong decision and should've just went with the 56. I thought the 58cm Scott, with about 20mm larger HT length and Stack would be good for someone with long legs and a bad lower back, but I don't know how much difference 5mm reach and 15mm top tube would matter or if I could fix (potential) reach issues.

I'm 6'1" with a 35" cycling inseam, so I've always had trouble finding the "perfect fit" stock bike as I seem to be on either the large end of a 56 (feeling slightly cramped and with too much saddle -> bar drop) or the small end of a 58 (feeling a little too stretched out).

pdedes

i buy most of my bikes unseen using geometry charts. if the bike can put the parts where you need them without crazy stem lengths (<10cm >14cm) so that it handles appropriately, you can get yourself a winner. bikes are somewhat adjustable. bodies are somewhat adaptable

RoadLight

Hi Anti404,

Based on your description, it sounds like you made the correct choice with a 58" frame size. I'm 6'2" with a 34" inseam and ride a 58" frame. I wouldn't want a smaller frame because of the seat post height that I'd need---your 35" inseam would be more severe and would argue against a too-small frame. I could probably tolerate a little more reach (longer top tube) which makes me think that the reach should be just about right for you. Just be prepared to use a short stem, if necessary.

It is possible to adjust the fit of a bike by changing the contact points (seat, seat post, stem, stack height, handlebar, crank arm length, etc) and this usually means that you can successfully fit a cyclist to a slightly smaller frame. But fitting someone to a larger-than-optimal frame can be problematic. And this can vary tremendously from one manufacturer and model to the next.

I've ridden mostly Fuji road bikes, starting with a 1985 quad-butted steel Fuji to a 2008 composite carbon Team Fuji today. The classic road geometry used by Fuji has always fit me well. Once you find a manufacturer who makes a style of frame that fits you well, you'll be tempted to stay with them, too.

If you need a little more height at the handlebar for a more relaxed ride, consider adding a stem height extender. Delta Cycle makes a decent alloy one that's available in a couple of different heights. Because the head tube of the frame is angled back toward you, the stem height extender also moves the stem and handlebars a little closer to you. They are great for those of us who find that we cannot bend our necks as much as we did when we were younger. By raising the shoulders a little, we can still see the road.

It's common to see professional road cyclists riding on smaller frames. One of the biggest reasons for this is to shed weight so as to increase their speed. The rest of us should focus on comfort and start with an optimal frame size based on our body dimensions.

Kind regards, RoadLight

Anti404

Thanks, RL and pd. I appreciate your input about fitting.

The thing I found odd was that bikes, particularly the endurance style bikes, are so similar in their measurements (namely, reach). I found it odd that the 56cm and 58cm Scott Solace only differed by about 5mm in reach and about 20mm in stack. For me that made it relatively difficult to decide between similarly sized bikes, and the people at the shops seemed just as perplexed as I.

dr_lha

You're surprised that a bike with a 2cm difference in size, differed by only 2cm?

dr_lha

You need to hammer on the crankset until the frame breaks, then buy one that uses a threaded bottom bracket.

Anti404

Hah, I suppose that my line of thinking doesn't make a whole lot of sense when you put it that way... I guess I assumed that because it is a triangle that 2cm in one direction doesn't necessarily mean 2cm in another, but if they are changing HT angle (which is changed), that would account for some of that...

I guess what is more (pleasantly) surprising is that if the reach of one size doesn't work too well it can easily be modified through changing stem angle and length.

Chi_Z

don't worry about toptube length, you should just focused on reach and stack because they are based on BB to stem, from my research, trek domane has the shortest reach with highest stack in a size 56 compared to Roubaix, look 765, defy etc. Even though domane has shorter HT than roubaix, but the extra BB drop makes up for it. it's always easier in increase the stack then shorten a reach. Smaller bike is also lighter and corners better due to shorter wheelbase. Lets face it, a 12mm stem looks much sexier than a 80mm stem

Dean V

Because reach is measured at the stack height as the stack increases reach will decrease if the top tube length stays the same. This is due to the angle of the steering head and the way they measure stack/reach. If you look at a picture of how its measured it should make sense.
So if the frame has 20mm more stack and 5mm more reach the extra reach is really - (tan 17 degrees x 20) + 5mm = 6.1mm + 5mm = 11.1mm.