Go Back  Bike Forums > Bike Forums > Road Cycling
Reload this Page >

Small differences between different sized bikes?

Notices
Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

Small differences between different sized bikes?

Old 09-18-16, 07:52 AM
  #1  
Senior Member
Thread Starter
 
Join Date: Jun 2008
Location: Indiana
Posts: 514

Bikes: 2015 Scott Solace 30, 2007 CAAD9 Optimo 1

Likes: 0
Liked 1 Time in 1 Post
Small differences between different sized bikes?

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).
Anti404 is offline  
Old 09-18-16, 08:32 AM
  #2  
ka maté ka maté ka ora
 
pdedes's Avatar
 
Join Date: Oct 2008
Location: wessex
Posts: 4,423

Bikes: breezer venturi - red novo bosberg - red, pedal force cg1 - red, neuvation f-100 - da, devinci phantom - xt, miele piste - miche/campy, bianchi reparto corse sbx, concorde squadra tsx - da, miele team issue sl - ultegra

Likes: 0
Liked 4 Times in 4 Posts
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
pdedes is offline  
Old 09-18-16, 02:35 PM
  #3  
Senior Member
 
RoadLight's Avatar
 
Join Date: Oct 2014
Posts: 195
Likes: 0
Liked 4 Times in 4 Posts
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
RoadLight is offline  
Old 09-19-16, 08:11 AM
  #4  
Senior Member
Thread Starter
 
Join Date: Jun 2008
Location: Indiana
Posts: 514

Bikes: 2015 Scott Solace 30, 2007 CAAD9 Optimo 1

Likes: 0
Liked 1 Time in 1 Post
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.
Anti404 is offline  
Old 09-19-16, 08:18 AM
  #5  
Senior Member
 
Join Date: Oct 2014
Location: Central PA
Posts: 4,843

Bikes: 2016 Black Mountain Cycles Monster Cross v5, 2015 Ritchey Road Logic, 1998 Specialized Rockhopper, 2017 Raleigh Grand Prix

Liked 16 Times in 11 Posts
Originally Posted by Anti404
I found it odd that the 56cm and 58cm Scott Solace only differed by about 5mm in reach and about 20mm in stack.
You're surprised that a bike with a 2cm difference in size, differed by only 2cm?
dr_lha is offline  
Old 09-19-16, 08:20 AM
  #6  
Senior Member
 
Join Date: Oct 2014
Location: Central PA
Posts: 4,843

Bikes: 2016 Black Mountain Cycles Monster Cross v5, 2015 Ritchey Road Logic, 1998 Specialized Rockhopper, 2017 Raleigh Grand Prix

Liked 16 Times in 11 Posts
You need to hammer on the crankset until the frame breaks, then buy one that uses a threaded bottom bracket.
dr_lha is offline  
Old 09-19-16, 11:12 AM
  #7  
Senior Member
Thread Starter
 
Join Date: Jun 2008
Location: Indiana
Posts: 514

Bikes: 2015 Scott Solace 30, 2007 CAAD9 Optimo 1

Likes: 0
Liked 1 Time in 1 Post
Originally Posted by dr_lha
You're surprised that a bike with a 2cm difference in size, differed by only 2cm?
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.
Anti404 is offline  
Old 09-19-16, 01:58 PM
  #8  
Senior Member
 
Chi_Z's Avatar
 
Join Date: Dec 2013
Posts: 507

Bikes: Niner RLT 9 RDO

Liked 69 Times in 50 Posts
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
Chi_Z is offline  
Old 09-19-16, 02:07 PM
  #9  
Senior Member
 
Join Date: Oct 2009
Posts: 2,853
Likes: 0
Liked 259 Times in 153 Posts
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.
Dean V is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
johngwheeler
Road Cycling
17
07-13-17 04:24 PM
ejewels
General Cycling Discussion
8
08-07-16 07:18 PM
wchevron
Fitting Your Bike
4
10-20-14 11:16 PM
portland376
Road Cycling
1
12-09-09 11:33 AM

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Your Privacy Choices -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.