Bike fit question
03-05-19, 01:23 AM
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Bike fit question
I am a 5'7 male with 29 inch inseam, and I ride a 49cm roubaix. Before I bought the bike, I thought it might be a tad small for me, but I got a bike fit, fitted a 110mm stem and am pretty comfy but experiencing a bit of twitchness at times. If I were to buy one size up, 52cm, will I see any SIGNIFICANT changes to the bike fit? Will the twitchiness go away dramatically?
03-05-19, 01:47 AM
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https://www.competitivecyclist.com/S...latorBike.jsp? No one knows. A Roubaix shouldn't be twitchy .... Unless it is a Fuji Roubaix. A Specialized Roubaix should be sort of relaxed.
Your best bet is to try the larger bike. I would expect a bike to be "twitchy" if it had a lot of weight forward--a lot of weight on the front wheel---or if it had a really steep head-tube angle, like 74 degrees. If the top tube is a little short, maybe you are leaning too far forward and that might make the bike feel "twitchy." I don't know. Again, Specialized or Fuji?
These is a whole lot which goes into fitting a rider to a bike. Height and inseam really don't mean a lot. Your personal proportions---arm and leg length versus torso length--and your flexibility, really determine what is best---and it changes for every bike, and changes depending on who much you ride.
Also ... a "bike fit" might mean the guy at the shop made the bike he needed to sell, fit the person who was willing to ride it. There is no magic frame size which will fit you---you could probably ride smaller and much larger, using different stems, seat-post set-back, saddle locations, and bars.
That's my story. Don't care who believes it.
Hopefully someone else here has personal experience with the specific bikes and sizes .....
Your best bet is to try the larger bike. I would expect a bike to be "twitchy" if it had a lot of weight forward--a lot of weight on the front wheel---or if it had a really steep head-tube angle, like 74 degrees. If the top tube is a little short, maybe you are leaning too far forward and that might make the bike feel "twitchy." I don't know. Again, Specialized or Fuji?
These is a whole lot which goes into fitting a rider to a bike. Height and inseam really don't mean a lot. Your personal proportions---arm and leg length versus torso length--and your flexibility, really determine what is best---and it changes for every bike, and changes depending on who much you ride.
Also ... a "bike fit" might mean the guy at the shop made the bike he needed to sell, fit the person who was willing to ride it. There is no magic frame size which will fit you---you could probably ride smaller and much larger, using different stems, seat-post set-back, saddle locations, and bars.
That's my story. Don't care who believes it.
Hopefully someone else here has personal experience with the specific bikes and sizes .....
03-05-19, 01:03 PM
#3
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Twitchy can mean different things to me. One of my bikes I can describe as twitchy, but it's also the bike that I can maneuver quickly and with more assured safety for myself when I have to leave the line I planned to ride in a turn or around a group of riders or deer jumping out across the trail. The other bike can be steady and confidence building, but less forgiving when I need to suddenly alter my planned path.
If you got a fit from someone that seemed knowledgeable at the shop, then discuss what you are feeling with them. It might be you can adjust the saddle back or change something else without sacrificing the fit. IMO, fits can be geared toward performance or comfort. So there is room to compromise between the two opposing criteria.
If you got a fit from someone that seemed knowledgeable at the shop, then discuss what you are feeling with them. It might be you can adjust the saddle back or change something else without sacrificing the fit. IMO, fits can be geared toward performance or comfort. So there is room to compromise between the two opposing criteria.
03-05-19, 03:58 PM
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We have similar dimensions. I recently purchased, and ride, a 52cm Specialized Allez Sprint. I went from a 90mm to a 110mm stem, just as you did. I came to the conclusion that I needed a longer stem after doing a couple rides. I did my research and found the suggested sizing charts from Specialized. I/we fall between sizes 52 and 54. I chose to
go with the smaller frame and to tailor it to my sizing. Smaller=better to some because of the decreased weight and increased rigidity.
I would say that my bike (Allez Sprint) is the definition of twitchy. I noticed that the smallest amount of bar input leads to an immediate change in direction. I have to be mindful when at speed and traveling downhill. Like others mentioned, when weighting the front wheel while using the brakes, or climbing, the bike can exhibit a twitchy feeling. You could try using more of your core muscles in order to alleviate pressure/weight from the handlebars. The same principle applies to riding sport motorcycles, which I do, and have applied the same logic and fit to bicycling.
go with the smaller frame and to tailor it to my sizing. Smaller=better to some because of the decreased weight and increased rigidity.
I would say that my bike (Allez Sprint) is the definition of twitchy. I noticed that the smallest amount of bar input leads to an immediate change in direction. I have to be mindful when at speed and traveling downhill. Like others mentioned, when weighting the front wheel while using the brakes, or climbing, the bike can exhibit a twitchy feeling. You could try using more of your core muscles in order to alleviate pressure/weight from the handlebars. The same principle applies to riding sport motorcycles, which I do, and have applied the same logic and fit to bicycling.
03-05-19, 09:30 PM
#5
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Interesting dilemma OP. I am the same size as you, 5’7”,29” inseam, and my average weight is 150lbs. I bought a 2016 54cm Spec Roubaix sl4 Comp new. After considerable adjustments, I ride it with the stock 100mm stem reversed at -16 degrees; stock saddle at -4 degrees, 16 3/4” from nose to center of stem cap; 28” from center of cran k to top of saddle. Love the fit. I also use Spec Roubaix Pro 700x25-28c tires with Challange 700x19-28c seamless latex inner tubes with 85psi front and 85-90psi (depending on road conditions) rear. Ride is very stable and smooth, yet still nimble enough for my needs.
Bike fit and feel are very personal and highly subjective. This works for me. Hope this helps. Good luck.
Bike fit and feel are very personal and highly subjective. This works for me. Hope this helps. Good luck.
03-05-19, 11:00 PM
#6
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Overall balance on a bike can influence perceptions of twitchiness. This time last year I switched from a 125mm to 90mm stem, mostly to ease strain on an old neck injury. It was more comfortable, less stretched out, but also felt twitchier. It was particularly noticeable on fast curves with rippled pavement -- I really had to pay attention.
At the same time I was working on improving neck and back conditioning, and following some basic bike fit guidelines. I read lots of websites, watched lots of tutorials, and generally found John Weirath's tips and conversational approach to be useful.
I raised the stem about 1/4", based on the usual test of a controlled leaning forward and backward without pushing away from the handlebar or falling forward and catching myself. The twitchy sensation disappeared. It shifted the balance just enough to fix that perception. Also helped me stay in the drops longer, helpful riding into headwinds.
I repeated the process after swapping saddles a month or so ago, from a minimally padded flat Selle Italia with rigid shell, to a more padded and curved Selle Italia with pressure relief cutout and flexible shell. I wanted to try aero bars and the position was causing uncomfortable perineum pressure. Usually I prefer a saddle level, but with the new saddle it was really uncomfortable in the aero bar. The twitchy sensation returned using the regular handlebar position -- hoods and drops. Not good, especially when I already wasn't comfortable using aero bars.
I tilted the nose down a bit, and scooted the saddle fully forward on the rails. Raised the stem another 1/8" -- the bar is still about 2 and 1/2" below saddle height. No more twitchy sensation. Felt good on a fast 6 mile time trial route with some fast curves on rippled pavement, lots of short, steep hills, etc.
Turns out the newer Selle Italia doesn't feel like it's tilted nose down when I'm in the saddle and it's adjusted to suit me -- the more flexible shell gives enough that my actual position feels level. I'm not pushing myself backward from the handlebar. Makes a difference in the sensation of balance and whether the bike feels twitchy or calm.
Just a few fairly minor adjustments to bike fit.
At the same time I was working on improving neck and back conditioning, and following some basic bike fit guidelines. I read lots of websites, watched lots of tutorials, and generally found John Weirath's tips and conversational approach to be useful.
I raised the stem about 1/4", based on the usual test of a controlled leaning forward and backward without pushing away from the handlebar or falling forward and catching myself. The twitchy sensation disappeared. It shifted the balance just enough to fix that perception. Also helped me stay in the drops longer, helpful riding into headwinds.
I repeated the process after swapping saddles a month or so ago, from a minimally padded flat Selle Italia with rigid shell, to a more padded and curved Selle Italia with pressure relief cutout and flexible shell. I wanted to try aero bars and the position was causing uncomfortable perineum pressure. Usually I prefer a saddle level, but with the new saddle it was really uncomfortable in the aero bar. The twitchy sensation returned using the regular handlebar position -- hoods and drops. Not good, especially when I already wasn't comfortable using aero bars.
I tilted the nose down a bit, and scooted the saddle fully forward on the rails. Raised the stem another 1/8" -- the bar is still about 2 and 1/2" below saddle height. No more twitchy sensation. Felt good on a fast 6 mile time trial route with some fast curves on rippled pavement, lots of short, steep hills, etc.
Turns out the newer Selle Italia doesn't feel like it's tilted nose down when I'm in the saddle and it's adjusted to suit me -- the more flexible shell gives enough that my actual position feels level. I'm not pushing myself backward from the handlebar. Makes a difference in the sensation of balance and whether the bike feels twitchy or calm.
Just a few fairly minor adjustments to bike fit.
Last edited by canklecat; 03-05-19 at 11:04 PM.
03-06-19, 12:38 AM
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not directly on point, but Mr. @canklecat---it is good to hear that your physical condition is improving.
03-06-19, 01:00 AM
#8
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Yup, it's almost a relief to be "worrying" about minor stuff like bike fit and getting a little stronger, rather than the other stuff from last year.
03-06-19, 11:30 AM
#9
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If 29 inches is your cycling inseam, those are some short legs, which means a long torso. A common mistake if you saddle height is low, so it produces less setback, is no having the saddle back far enough. Definitely use a post with 20-25mm of setback.
FWIW, I'm the same height, but my cycling inseam is 32-5/8" or 83cm and my saddle height is 73cm. I always use a 25mm setback post because most small frames have a STA around 74 degrees. Even with my short torso, I use a 110mm stem and large 10cm saddle to bar drop, but I also use short reach Easton EC90 bars and Campy levers that have a shorter reach than the other brands.
What you really want to look at is the frame reach. My latest bike has a 382mm reach with a 527mm stack, which is plenty long for my short torso.
Beware when comparing reach, because an accurate comparison can only be made when the stack heights are about the same. If the next size up has a 20mm taller stack, the reach difference will be 6mm greater than shown on the geometry chart.
FWIW, I'm the same height, but my cycling inseam is 32-5/8" or 83cm and my saddle height is 73cm. I always use a 25mm setback post because most small frames have a STA around 74 degrees. Even with my short torso, I use a 110mm stem and large 10cm saddle to bar drop, but I also use short reach Easton EC90 bars and Campy levers that have a shorter reach than the other brands.
What you really want to look at is the frame reach. My latest bike has a 382mm reach with a 527mm stack, which is plenty long for my short torso.
Beware when comparing reach, because an accurate comparison can only be made when the stack heights are about the same. If the next size up has a 20mm taller stack, the reach difference will be 6mm greater than shown on the geometry chart.
03-06-19, 09:52 PM
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If 29 inches is your cycling inseam, those are some short legs, which means a long torso. A common mistake if you saddle height is low, so it produces less setback, is no having the saddle back far enough. Definitely use a post with 20-25mm of setback.
FWIW, I'm the same height, but my cycling inseam is 32-5/8" or 83cm and my saddle height is 73cm. I always use a 25mm setback post because most small frames have a STA around 74 degrees. Even with my short torso, I use a 110mm stem and large 10cm saddle to bar drop, but I also use short reach Easton EC90 bars and Campy levers that have a shorter reach than the other brands.
What you really want to look at is the frame reach. My latest bike has a 382mm reach with a 527mm stack, which is plenty long for my short torso.
Beware when comparing reach, because an accurate comparison can only be made when the stack heights are about the same. If the next size up has a 20mm taller stack, the reach difference will be 6mm greater than shown on the geometry chart.
FWIW, I'm the same height, but my cycling inseam is 32-5/8" or 83cm and my saddle height is 73cm. I always use a 25mm setback post because most small frames have a STA around 74 degrees. Even with my short torso, I use a 110mm stem and large 10cm saddle to bar drop, but I also use short reach Easton EC90 bars and Campy levers that have a shorter reach than the other brands.
What you really want to look at is the frame reach. My latest bike has a 382mm reach with a 527mm stack, which is plenty long for my short torso.
Beware when comparing reach, because an accurate comparison can only be made when the stack heights are about the same. If the next size up has a 20mm taller stack, the reach difference will be 6mm greater than shown on the geometry chart.
03-06-19, 09:55 PM
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https://www.competitivecyclist.com/S...latorBike.jsp? No one knows. A Roubaix shouldn't be twitchy .... Unless it is a Fuji Roubaix. A Specialized Roubaix should be sort of relaxed.
Your best bet is to try the larger bike. I would expect a bike to be "twitchy" if it had a lot of weight forward--a lot of weight on the front wheel---or if it had a really steep head-tube angle, like 74 degrees. If the top tube is a little short, maybe you are leaning too far forward and that might make the bike feel "twitchy." I don't know. Again, Specialized or Fuji?
These is a whole lot which goes into fitting a rider to a bike. Height and inseam really don't mean a lot. Your personal proportions---arm and leg length versus torso length--and your flexibility, really determine what is best---and it changes for every bike, and changes depending on who much you ride.
Also ... a "bike fit" might mean the guy at the shop made the bike he needed to sell, fit the person who was willing to ride it. There is no magic frame size which will fit you---you could probably ride smaller and much larger, using different stems, seat-post set-back, saddle locations, and bars.
That's my story. Don't care who believes it. Hopefully someone else here has personal experience with the specific bikes and sizes .....
Your best bet is to try the larger bike. I would expect a bike to be "twitchy" if it had a lot of weight forward--a lot of weight on the front wheel---or if it had a really steep head-tube angle, like 74 degrees. If the top tube is a little short, maybe you are leaning too far forward and that might make the bike feel "twitchy." I don't know. Again, Specialized or Fuji?
These is a whole lot which goes into fitting a rider to a bike. Height and inseam really don't mean a lot. Your personal proportions---arm and leg length versus torso length--and your flexibility, really determine what is best---and it changes for every bike, and changes depending on who much you ride.
Also ... a "bike fit" might mean the guy at the shop made the bike he needed to sell, fit the person who was willing to ride it. There is no magic frame size which will fit you---you could probably ride smaller and much larger, using different stems, seat-post set-back, saddle locations, and bars.
That's my story. Don't care who believes it.
Hopefully someone else here has personal experience with the specific bikes and sizes .....
03-09-19, 04:10 PM
#13
Senior Member
Death Grip
"Its not always twitchy but, sometimes when Im going downhill fast, feels more twitchy than my previous 54cm bike, and end up gripping the handlebars super tight."
Try relaxing the death grip.
Any balancing/correcting motions from your upper body are becoming "steering input" due to an overly rigid grip,imo.
Try "steering with your hips" (think about how you steer "hands free").
Try relaxing the death grip.
Any balancing/correcting motions from your upper body are becoming "steering input" due to an overly rigid grip,imo.
Try "steering with your hips" (think about how you steer "hands free").
03-09-19, 05:04 PM
#14
Senior Member
What does the bike feel like riding no hands on the bar?
My 52cm Vitus is unstable at low speed and needs you to really pay attention. Also it feels like it falls "into" sharp turns. Like it wants to turn more. Any little shift of balance on the bike immediately produces a course change. Im not really a fan of this, but there is no obvious clues in the geometry chart. Wish I could be of help, but you are not alone.
My 52cm Vitus is unstable at low speed and needs you to really pay attention. Also it feels like it falls "into" sharp turns. Like it wants to turn more. Any little shift of balance on the bike immediately produces a course change. Im not really a fan of this, but there is no obvious clues in the geometry chart. Wish I could be of help, but you are not alone.
Last edited by Racing Dan; 03-09-19 at 05:10 PM.
03-10-19, 03:47 PM
#15
Senior Member
What does the bike feel like riding no hands on the bar?
My 52cm Vitus is unstable at low speed and needs you to really pay attention. Also it feels like it falls "into" sharp turns. Like it wants to turn more. Any little shift of balance on the bike immediately produces a course change. Im not really a fan of this, but there is no obvious clues in the geometry chart. Wish I could be of help, but you are not alone.
My 52cm Vitus is unstable at low speed and needs you to really pay attention. Also it feels like it falls "into" sharp turns. Like it wants to turn more. Any little shift of balance on the bike immediately produces a course change. Im not really a fan of this, but there is no obvious clues in the geometry chart. Wish I could be of help, but you are not alone.
"...no obvious clues in the geometry chart".
To the original poster:
Can you provide some metrics from the offending frame? ie.
Wheelbase, Head Tube Angle, Seat Tube Angle, Straight Bladed Fork? ForkRake/Trail?
Also a picture of the bike against a neutral back drop from the drive-side could help.
I think I'd enjoy the discussion.
Some others might as well.
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