Bike Forums

Bike Forums (https://www.bikeforums.net/forum.php)
-   Fifty Plus (50+) (https://www.bikeforums.net/forumdisplay.php?f=220)
-   -   Adjusting a too small frame (https://www.bikeforums.net/showthread.php?t=1172885)

trek330 05-13-19 06:47 AM

Adjusting a too small frame
 
Will someone explain to me why a too small frame for your height can not be ideally adjusted?Wouldn't a longer stem, higher seat slightly more aft,and maybe longer crank compensate nicely for a 52cm frame when a 54 is your size?

Lemond1985 05-13-19 06:59 AM

You would think so, but it's more complicated than that. The top tube will sit lower, so you will need a higher, longer stem. When you stand up on the pedals, you'll be tossing a tiny frame from side to side, which will feel less stable than the correct size frame.

You can make seat post and stem corrections, but a smaller frame just has a different feel to it. More "flickable", meaning responsive, but less stable, meaning more on the "twitchy" side when it comes to handling.

In general, a larger frame will tend to be more stable, and suited for cruising in a straight line with no-hands riding, etc., whereas a smaller frame will perform better when climbing and sprinting out of the saddle a lot (i.e., racing). Take yer pick.

Barrettscv 05-13-19 07:21 AM

I have one frame that is marginally too small. I used a slightly longer stem and a deeper handlebar to increase the reach slightly. Resist the temptation to move the saddle back from your standard position, it can cause an uncomfortable fit.

I compromised by reducing the reach while including a longer stem. It’s a good fit for a fast ride but less than ideal for a century.

Wildwood 05-13-19 09:20 AM

Only 2 cm off your ideal frame size should give you room to make it fit.

My ideal size is 60cm. For a while 62-63cm frames were my ‘thing’ with a comfortably stretched position. Lately, I’ve been riding 58cm frames and appreciate the responsive ride.

Caveats - 2/3 of my rides are 30 miles or less, so fit isn’t a huge issue for a 2 hour jaunt. I’ve also been riding for 35+ years and have no skeletal issues to speak of. I also think my flexibility is pretty good (but what’s the measure?).

Headtube length is a measurement that’s more important to me than seattube length.
Pics of a smaller vs larger frame.

edit: As mentioned by @Barrettscv, handlebars can make a big difference, often overlooked as tube lengths and stem dominate fit discussions.

https://cimg6.ibsrv.net/gimg/bikefor...3a01d8d75.jpeg

58cm Bottecchia with 16cm headtube (my minimum)
https://cimg5.ibsrv.net/gimg/bikefor...27b5b20a3.jpeg

62cm AustroDaimler with 20cm headtube

trek330 05-13-19 09:41 AM

My thing is this.I just bought a bike on e-bay that was listed as 54 but on closer examination and checking the dimensions in the catalogue is actually a 51!The pic looked less than 54.BTW there is no 54 in the catalogue there is a 51 and 53. but I thought perhaps it was just the bike like some pants run small.I posted about the bike in Vintage.It's a 2002 Lemond Tourmalet.I've decided not to cancel as the price was good and it's exactly what I was looking for if a little smaller than I'd wish.BTW my inseam is 28 which is shorter than most people my height 5'8'.

Barrettscv 05-13-19 10:12 AM


Originally Posted by trek330 (Post 20927529)
My thing is this.I just bought a bike on e-bay that was listed as 54 but on closer examination and checking the dimensions in the catalogue is actually a 51!The pic looked less than 54.BTW there is no 54 in the catalogue there is a 51 and 53. but I thought perhaps it was just the bike like some pants run small.I posted about the bike in Vintage.It's a 2002 Lemond Tourmalet.I've decided not to cancel as the price was good and it's exactly what I was looking for if a little smaller than I'd wish.BTW my inseam is 28 which is shorter than most people my height 5'8'.

Lemonds have unusually long top-tubes and tend to fit bigger than the seat-tube measurement would indicate. I would compare the top-tube length to that of your other bike(s). Top-tube length is the primary fit dimension IMO.

tcs 05-13-19 11:21 AM

Food for thought: There are bikes that are offered 'one size fits most': traditional American balloon tire cruisers, folding bikes, BMX bikes, even the high-performance machines from Alex Moulton. The 'compact' frame design pioneered by Giant is successfully offered in far fewer sizes than traditional road bikes.

Lemond1985 05-13-19 11:31 AM


Originally Posted by Barrettscv (Post 20927594)
Lemonds have unusually long top-tubes and tend to fit bigger than the seat-tube measurement would indicate. I would compare the top-tube length to that of your other bike(s). Top-tube length is the primary fit dimension IMO.

I had always heard this, and using Greg's own suggestions for a 5' 10" rider, I *should* be on a 53 cm Lemond frame. I found out two things, 1.) that his frames are really not that much longer in the top tube than other brands, and 2.) I will never in a million years be comfortable on any 53 cm frame.

I eventually bought a Tourmalet in 55 cm, and the fit was pretty good. I think I could also be comfortable on one of his 57's, but a 53 would have been ridiculously small for me.

So I would treat Lemonds like any other frame size-wise, the supposedly long top tubes really aren't that long, IMO.

79pmooney 05-13-19 12:17 PM

My take? If the contact points (seat and bars) are right and your weight is well placed between the wheels, frame size matters little save the top tube contacting your leg in different places and bie bike "feel" being different due largely to the (presumably) different wheelbase. I've ridden (and got the fit right for) 62 cm frames, 59 and 58 (my "best), 56 and probably a 53. The 53 is an old Raleigh Competition. I have a 140 stem set not very high. Feels perfect.

Oh, a word on my sloped line reach theory. For me - any location of handlebar tops on a line that has a "slope" of 1 cm steerer spacers and 2 cm of horizontal reach is equal comfort and speed. In other words, I can have the bars so low ans close I hit them with my knees climbing or nearly up at seat level but much further forward and be equally comfortable. That line is an approximation of the arc my hands would swing through with my most comfortable lean forward and elbow bend.

I came up with this theory when I picked up that 62 cm frame. It was a laid back touring frame. I always felt cramped climbing on it with a slammed 130 stem. Drew it and my custom on the same paper, sharing the BB location. Sketched in where my shoulders would be. Swung the arc through my custom's bars. Saw where it hit the much higher stem height for that big frame. (All my bikes have old-school horizontal stems.) Measured the distance steerer to intersection. 7" Went to a local framebuilder and had a 7" stem made. (178 mm) Worked! Really well! I rode 20,000 miles on that bike and stem until it died a violent death. Later I set up a 56 cm fix gear with a near slammed 130. Other end of that line. Knee contact was happened. A hot, fun custom pure $105 race bike! Loved it!

So, when I look at a potential bike, I measure it up to see where the stem is relative to the BB. Go home and sketch it up. Lay my "line" over the drawing. Now, what stem height and reach is required to place the bars on that line? Is that stem reasonable and available? Do I want this bike to have bars (say) that low and close or far and high?

I also look at where my weight is. Years ago I weighed the front and rear wheels of one of my bikes with me on it. (Phone books under the other wheel so the bike was level.) Did the math and computed where my weight was located relative to the bottom bracket. So I look at whether that location works well with where the wheels are on this prospective bike.

The bike that doesn't meet those two criteria is a bike I won't go back and buy. If it does (and it is a bike I really want), the frame size is not a consideration. (Well, I like horizontal top tubes and ones that might be life altering, I stay away from.)

Edit: This may have already come across in this post. I am perfectly willing to use unusual stems and seatposts to nail the fit. My last two customs have steep seat angles (for optimum rear wheel placement weight-wise on one and for a very long dropout on another) and custom seatposts with huge setbacks. (60 mm) I've had stems made of 178, 180, 175 and 155 mm. Love the Nitto Pearl 13s that actually measure 140 mm.

Ben

95RPM 05-13-19 05:31 PM


...and custom seatposts with huge setbacks
Where do you get such a seatpost? I could use one.

canklecat 05-14-19 01:42 AM

At 5'11" with 33" inseam, I must be an awkward in-between size. Both 56 and 58cm road bike frames feel okay to me. Some differences in balance and feel, but after a few minutes on the bikes I hardly notice. I'm just guessing at the frame sizes, though. They aren't marked on the bikes. Neither frame perfectly matches manufacturers' claimed specs for C-T-C measurements. The nominally 58cm frame seems more like 57 with my measurements. Eh, who knows.

I adjust the saddle fore/aft positions to suit my knees, height to suit my hips -- I tend to prefer a long leg extension, but back off when I begin to feel some twinges in the hips and lower back. My 58cm frame has the saddle fully forward on a typical setback post. My 56cm frame bike has the saddle fully back on the rails. I twiddle the positions a bit to suit my sit-bones on the sweet spot of my Selle Italia saddles, which have been a comfortable design for me.

At the moment I'm not fiddling much with stem length or height since I'm back in physical therapy for neck and shoulder injuries. As PT progresses I may become more comfortable with the fairly stretched out position. For now it's fine for 20-30 mile rides with maybe one brief rest break to stretch a bit.

Barrettscv 05-14-19 03:21 AM


Originally Posted by 95RPM (Post 20928438)
Where do you get such a seatpost? I could use one.

Velo Orange has one: https://velo-orange.com/collections/...t-long-setback

Lemond1985 05-14-19 05:07 AM

In 27.2 mm only. :(

jppe 05-14-19 05:57 AM

Has anyone using a “frame too small” experienced a shimmy on fast descents? Just wondering if that could be a factor as well. Those can be frightening!

Wildwood 05-14-19 09:24 AM


Originally Posted by jppe (Post 20929032)
Has anyone using a “frame too small” experienced a shimmy on fast descents? Just wondering if that could be a factor as well. Those can be frightening!

i don’t consider my 58 frames “too small” just the bottom of my range - but NO Shimmy. And I frequently hit speeds in the 30s.

bruce19 05-14-19 10:58 AM

which of the three styles of fit are you? - Australian Cycling Forums - Bicycles Network Australia

Some good info here. I can ride a 54 to a 56 pretty well. And, I believe most of us can fit a range of sizes. Figuring out what that range is, is a very individual thing.

Carbonfiberboy 05-14-19 12:45 PM

If you really have a pubic bone to floor measurement of 28", the 51 will not be too small for you. You'll probably need a set-back post and a longish stem.

peterws 05-14-19 01:01 PM

I bought a bike with a small frame; tried out one and found out it was for a female. It was tight, light, felt like a little motorbike with a big engine. I think I must have got a unisex one . . . I changed the handle bars to suit my benighted status (everyone calls me "sir" now) which comes with age. But these might suit anyone who likes comfort and security. You can stop on a sixpence (dime) using the original shifters. See what y'all think!

https://drive.google.com/file/d/11vP...ew?usp=sharing

https://drive.google.com/file/d/1BLt...ew?usp=sharing

The lower drops are for hill climbing. You don't need brakes for hill climbing.

bruce19 05-14-19 01:19 PM


Originally Posted by Lemond1985 (Post 20927759)
I had always heard this, and using Greg's own suggestions for a 5' 10" rider, I *should* be on a 53 cm Lemond frame. I found out two things, 1.) that his frames are really not that much longer in the top tube than other brands, and 2.) I will never in a million years be comfortable on any 53 cm frame.

I eventually bought a Tourmalet in 55 cm, and the fit was pretty good. I think I could also be comfortable on one of his 57's, but a 53 would have been ridiculously small for me.

So I would treat Lemonds like any other frame size-wise, the supposedly long top tubes really aren't that long, IMO.

As I recall the LeMond-Guimard sizing formula is based inseam not height. And, if I recall correctly, it's .665 of inseam metric. I should mention that with a 32.5" (82.55 cm) a 54-55 frame fits me well.

ridingfool 05-14-19 01:56 PM


Originally Posted by tcs (Post 20927733)
Food for thought: There are bikes that are offered 'one size fits most': traditional American balloon tire cruisers, folding bikes, BMX bikes, even the high-performance machines from Alex Moulton. The 'compact' frame design pioneered by Giant is successfully offered in far fewer sizes than traditional road bikes.

Think most of those bikes are for riding maybe 5 miles at most so don't think fit is really too inportant give or take 2 cm either way but on a road bike when you . Want to ride 50 miles or more I think is is more important to dial your fit in as best is possible

CyclingFool95 05-14-19 02:51 PM

It's generally easier to fit a smaller frame than a larger one (I find that even one cm larger than my usual and I feel it leaning into turns), but bear in mind that many manufacturers tweak the angles on smaller frames, sometimes significantly.

95RPM 05-14-19 06:43 PM


Originally Posted by Barrettscv (Post 20928946)

It looks to be a good seatpost. Thanks.

tcs 05-15-19 08:55 AM

And Sheldon Brown weighs in:

https://www.sheldonbrown.com/frame-sizing.html

BobL 05-17-19 11:18 AM


Originally Posted by trek330 (Post 20927234)
Will someone explain to me why a too small frame for your height can not be ideally adjusted?Wouldn't a longer stem, higher seat slightly more aft,and maybe longer crank compensate nicely for a 52cm frame when a 54 is your size?

I'd say the tough part about answering that is how much it depends on your individual sizes; standover for your height, arm length, where you're comfortable, all that.

Having said that, I did exactly what you're talking about years ago (2003). I had been riding a Cannondale 52cm road bike and bought a 52cm Trek 5200 carbon fiber bike from eBay, not realizing the two of them measure frames differently - center to top vs center to center. The 5200 was too small. By getting a new seatpost and then shopping for a stem, I found a combination that made it a pleasure to ride. Yes, the smaller frame is more "twitchy", if you like that word. More responsive. About that time, there were interviews in the bike magazines saying that several pros liked the combination of smaller frame and longer stem for that reason.
https://cimg2.ibsrv.net/gimg/bikefor...0bf50fda82.jpg

The stem has a positive angle instead of negative (really parallel to the top tube) and was the longest one the bike shop had. The combination lifts the bars and pushes them forward. The seatpost is just a taller version. I've seen some that have a bend in the tube to push the saddle even farther back.

fietsbob 05-17-19 04:48 PM


Originally Posted by 95RPM (Post 20928438)
Where do you get such a seatpost? I could use one.

Nitto S 84 Chromoly seat post has a lot of setback
https://www.benscycle.com/nitto-s84-...84_870/product
https://www.benscycle.com/Assets/pro...ge/870-164.jpg


All times are GMT -6. The time now is 05:10 AM.


Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.