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Changing out stem on Centurion Comp TA
Hi. I'm slowly getting my Centurion Compt TA to where it's comfortable for me to ride (it's a bit big for me). I need to change to a shorter stem. When I asked my LBS, they said it takes a 1" quill stem and that I'd have to go on ebay to find one since they're not made anymore. Is there anything specific I should be looking for in the stem so that it fits the bike? Also, is there a good way to determine what stem length would be good for me? I'm not sure how long the stem is that is on the bike now but I'm guessing it may be the original stem. I'm new to this so forgive me if these questions sound elementary. Thank you in advance for any info! :)
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One thing that has always helped me when building up bikes is a decent digital caliper . They switch from inch to metric , don't get the ones that read in fractions . A good meter ruler will help too . Mine reads inch and cm . So anyhow back to your quill , besides quill dia . (yours is one inch) they measure in reach and that dimension is from center of the quill to the center of the bar clamp . The other dimension is bar clamp dia . So knowing these dims. you can start looking for a new one , I really like Shimano 600 stuff it's a reasonable price and plenty of it on the bay . There are a few of us that can talk the chicken off the bone when it comes to IM's and Comp TA's . We hang out here , come on over .
https://www.bikeforums.net/classic-v...-jobs-203.html |
Bull-pucky on “not made anymore”. Here’s a few: https://www.universalcycles.com/shop...category=1728# https://velo-orange.com/collections/stems Sutro Quill Stem | SOMA Fabrications You do need to know the clamping diameter of your bars. Possibilities for your older bike are: 26.0mm (quite likely), 25.4 or 26.4 (Cinelli bars only). Do NOT try to fit a larger diameter bar into a smaller stem clamp. However, shims (think aluminum can strips, or something made for that purpose) can be used for a smaller bar in a larger clamp. There’s no easy answer to the “correct stem length” (and height) question, since it’s a function of your torso and arm length, your flexibility and riding posture preference. When I was in my mid-40’s, My stems were 100-110mm and bars several inches below the saddle. Now at 69YO, stems are 80mm with shorter reach bars (another way to reduce reach), and just a centimeter or two below the saddle. https://photos.smugmug.com/Bicycles/...zeRender-S.jpg https://photos.smugmug.com/Bicycles/...22580333-S.jpg Stem length is measured, usually horizontally along the top, from the center of the quill bolt to the the center of the bar where it is clamped. For riser stems, that can be tricky, since there’s no actual horizontal element. You should also know that quill length can be longer to raise the bars. The Nitto Technomic found in the first two links above is the standard for seriously raising bars before progressing into riser stems, although the VO Gran Compe and Soma Sutro, which are essentially identical, are taller but very similar in elegance to the old classic stems and quite beautiful, but only available on 80mm and 100mm lengths. Other easy ways to shorten reach without buying anything, except possibly bar tape, is to rotate the bars in the stem until the upper curve is horizontal or even upward a touch, and/or move the brake posts upward on the curve of the bar. |
What DFROST said is exactly what I was thinking. Im sending you a PM [MENTION=471000]omg_my_butt[/MENTION]
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What size stem do you need? We need more info.
A picture is the key here. Or, measure the stem from the center of the steerer bolt hole to the center of the bar clamp area, and tell us what it is, inches or cm. Perhaps we can simply point you to a shorter stem and you can give it a shot. Short of seeing you on the bike, guessing is about all we can do. |
If the bike is too big for you, you might want to look for something 60mm. A lot of vintage bikes come with 80-100mm standard so you'll probably want smaller than that to make a significant difference. If you're new to riding or drop bar riding then going from 80 to 60 might not seem a big enough difference.
Your bike shop was wrong. They do still make them. Origin 8 makes a lot of sizes, with 26.0 bar clamp. I wouldn't be so quick to assume that it's 26.0 though as [MENTION=340794]Dfrost[/MENTION] said though. Someone correct me if I'm wrong but aren't 26.0 clamp bars typically the old ergo style, that have only existed since the later 80s, and 25.4 was still used for everything non ergo? The only 26.0 bars I see look something more like this: https://cimg1.ibsrv.net/gimg/bikefor...753110f3c9.jpg As opposed to this: https://cimg8.ibsrv.net/gimg/bikefor...9f1bdcb6be.jpg |
I usually suggest that the bike be tested out with the saddle moved forward before changing to a shorter stem, in cases where a subtle change is all that is needed to achieve a comfortable reach to the bars.
Unlike with moving the rider's center of mass rearward, the forward saddle keeps the rider nearer to the balance point above the pedals, making for an easier transition to the standing position needed for attacking hills. Making it less of an effort to rise out of the saddle can reduce one's need for lower gearing. Stems are easiest to find in the 80 and 90mm extension lengths these days, reflecting their use on bikes no longer used for sporting efforts. 60mm is also easy to find, but shorter lengths affect the way that the bike's steering response feels, possibly making an old racing bike feel too twitchy. Raising the bars also leads to more of a flighty steering feel, with less stability as speed increases. |
Originally Posted by omg_my_butt
(Post 20530631)
Hi. I'm slowly getting my Centurion Compt TA to where it's comfortable for me to ride (it's a bit big for me). I need to change to a shorter stem. When I asked my LBS, they said it takes a 1" quill stem and that I'd have to go on ebay to find one since they're not made anymore. Is there anything specific I should be looking for in the stem so that it fits the bike? Also, is there a good way to determine what stem length would be good for me? I'm not sure how long the stem is that is on the bike now but I'm guessing it may be the original stem. I'm new to this so forgive me if these questions sound elementary. Thank you in advance for any info! :)
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Wow thank you all for your informative replies! I'll try to post some pics of both the bars/stem and my riding posture on the bike as well as the stem measurement. I'll post a pic of that too, so you folks can tell me whether I got the right number. :foo:
Malcala622 - It looks like I can't get your PM since I have fewer than 10 posts... merziac - What is a C + V guy? Would I be able to replace the stem myself or do these require an actual bike mechanic? dddd - I asked at the LBS about moving the seat forward. He said it's as forward as it will go. I am going to get a new saddle, though, since the one that is on there is an old guy's saddle and, well, see my username. Stormy Archer - my bars look like the first pic you posted due to the engravings on either side. Dfrost - I would like to raise the bars also, but I'm not sure they can go up any farther. Also, if the bars are stock, would shorter reach bars make much of a difference (I've no clue here)? markwesti - I'll check out that forum. Thanks! |
Originally Posted by omg_my_butt
(Post 20532537)
Wow thank you all for your informative replies! I'll try to post some pics of both the bars/stem and my riding posture on the bike as well as the stem measurement. I'll post a pic of that too, so you folks can tell me whether I got the right number. :foo:
Malcala622 - It looks like I can't get your PM since I have fewer than 10 posts... merziac - What is a C + V guy? Would I be able to replace the stem myself or do these require an actual bike mechanic? dddd - I asked at the LBS about moving the seat forward. He said it's as forward as it will go. I am going to get a new saddle, though, since the one that is on there is an old guy's saddle and, well, see my username. Stormy Archer - my bars look like the first pic you posted due to the engravings on either side. Dfrost - I would like to raise the bars also, but I'm not sure they can go up any farther. Also, if the bars are stock, would shorter reach bars make much of a difference (I've no clue here)? markwesti - I'll check out that forum. Thanks! Yes, you can certainly do a stem swap yourself with relatively few tools. Some photos of what you have will simplify that process, when you can send them. We can walk you through that. You should also search YouTube, etc. and look in the Bicycle Mechanics forum. I’m more picky than [MENTION=185430]dddd[/MENTION] about seat fore/aft location, feeling that should be established for ride balance, relative to the bottom bracket. But that adjustment can be used as a quick way to gauge how much change will be needed. It’s unlikely that a different saddle will let you go farther forward if yours is already at that limit. Raising the bars is limited by the stem and it’s maximum insertion height, which should never be exceeded. The Nitto Technomic found in the links I sent in my previous post, as well as others mentioned, keeps the look of a classic stem, while adding several inches above that maximum insertion line. The various riser stems are another way to get even higher. Here I am with a VO Gran Compe (taller than classic stems, shorter than a Technomic), and again with VO’s steel riser stem. The latter could have been higher, but the common position in these shots I find very comfortable for rides of any length. https://photos.smugmug.com/Bicycles/...11484947-S.jpg https://photos.smugmug.com/Bicycles/...11492705-S.jpg Looking at online photos of Centurion Comp TA, your stock bars are pretty ‘deep’ (distance from the stem clamp to the forward most part of the bend), probably about 100cm or more. Newer bars like the frequently recommended Soma Highway One are 75mm in that dimension, and there are many variations. Again, make sure that the bar and stem clamping diameters match! https://www.universalcycles.com/shop...s.php?id=56846 And remember my suggestion to try rotating the bars in the stem or raising the brakes on the bar. Years ago as I lost torso length due to age, I realized I could shorten the reach by 1-1.5cm with that free adjustment. |
Originally Posted by omg_my_butt
(Post 20532537)
Wow thank you all for your informative replies! I'll try to post some pics of both the bars/stem and my riding posture on the bike as well as the stem measurement. I'll post a pic of that too, so you folks can tell me whether I got the right number. :foo:
Malcala622 - It looks like I can't get your PM since I have fewer than 10 posts... merziac - What is a C + V guy? Would I be able to replace the stem myself or do these require an actual bike mechanic? dddd - I asked at the LBS about moving the seat forward. He said it's as forward as it will go. I am going to get a new saddle, though, since the one that is on there is an old guy's saddle and, well, see my username. Stormy Archer - my bars look like the first pic you posted due to the engravings on either side. Dfrost - I would like to raise the bars also, but I'm not sure they can go up any farther. Also, if the bars are stock, would shorter reach bars make much of a difference (I've no clue here)? markwesti - I'll check out that forum. Thanks! cost. Be prepared to struggle and meet the challenge head on, you won't regret it when you persevere. We will be glad to help as you can see. Make it so. ;) |
Ok here are some photos - stem, stem measurement (hopefully it's readable), bars, seat position (looks all the way forward to me). I'll try to get a pic of me on the bike to show positioning.
https://cimg6.ibsrv.net/gimg/bikefor...8d59456fe1.jpg https://cimg5.ibsrv.net/gimg/bikefor...ef67489053.jpg https://cimg1.ibsrv.net/gimg/bikefor...adfdcc157d.jpg https://cimg8.ibsrv.net/gimg/bikefor...310c299cd5.jpg https://cimg5.ibsrv.net/gimg/bikefor...0d1281cb2b.jpg https://cimg2.ibsrv.net/gimg/bikefor...090ccaa7e5.jpg |
Uh, step back a bit.
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Here I am on the bike. Excuse the weirdness going on with my left leg. I had to balance against the table LOL. My elbows are pretty much locked and the reach causes a lot of pain in my upper back and neck (which is already messed up to begin with). It's hard to tell but my hands are on the hoods.
https://cimg6.ibsrv.net/gimg/bikefor...82c3e0af6f.jpg |
I'm guessing you ride a 54cm frame, maybe a 56cm, you look about 5'7" to 5'8" or thereabouts.
That appears to be a 58cm with a 95mm stem. No doubt the seat post is set back 25mm. Your height might equate to a 56cm, but your legs appear to be pointing to a 54cm. These are just generalities, mind you. 1-Right leg shouldn't be locked out, but then again, you're not moving. I'm guessing about 4" of seat post is a bit too much. 2-Those bars, in that era, have a good reach, as does that stem. It appears, for you, a bit long, but the drop to the shifters looks pretty good. Trying a borrowed zero-setback seat post and a shorter stem would give you a idea of you can ride that size, without spending money. Ask any bike shop who has the older bikes around, and maybe ask that person. He/She will be a lot of good info. If not, the Ironman cult can help you find a similar frame, perhaps, in your size, and you definitely have trade bait. Either a Comp TA or an Ironman. Of course, if you get an Ironman, you'll have to swat away the suitors. |
I don't know what size the frame is - I'll look up how to measure. I'm actually 5' 2.5"! LOL. When I'm actually riding my legs don't lock out at the bottom. I was just trying not to fall over in the photo. :D I'm now wondering if I have to change too much on this bike and should look for another. I'm kind of fond of it, though. As far as trading, how would I know what a fair trade would be?
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Originally Posted by omg_my_butt
(Post 20534329)
I don't know what size the frame is - I'll look up how to measure. I'm actually 5' 2.5"! LOL. When I'm actually riding my legs don't lock out at the bottom. I was just trying not to fall over in the photo. :D I'm now wondering if I have to change too much on this bike and should look for another. I'm kind of fond of it, though. As far as trading, how would I know what a fair trade would be?
Its a really nice bike for sure- predecessor to the Ironman. |
If you are 5'2" to 5'3", that frame size is too big. I'm so sorry about that. My guess is you need a 50cm or 52cm, and that's being very general. My guess is that the saddle is set pretty low on that frame.
My recommendation is to look for another frame or bike. That's not bad news, though, because you have excellent trade bait. A Comp TA is a nice bike. The next step, if I'm correct, is to measure that frame from the center of the crank arm spindle, up along the seat tube, to the lowest part of that scalloped top lug. That will give you the Seat Tube (ST) size, as Centurion measured. Then, measure, along the Top Tube (TT), from the center of the seat post to the center of the head tube. This will give you the TT size. Then, you will know what size you have to trade. I'd leave the bike assembled for now. If that is a 56cm, perhaps we can talk. It sure looks like a 58cm, but I can't tell. |
So much to agree with from these last few posts, but there are work-arounds to a too-large bike if the rider has no trouble getting on and off of the bike.
If the seatpost is needing to be at it's lowest height setting, then really the bike is too large and one would have to lean the bike over every time that they had to stop for a traffic light in order to put a foot flat on the ground! In less-severe cases, and where the rider is close to being positioned well while actually riding, a forward-leaning ("reversed") seatpost and perhaps some added auxiliary brake levers as shown below can make a bike much more ridable. I've put a lot of miles on this one (even with the 4-1/2" stem) and it actually is quite comfortable and safe to ride: https://cimg3.ibsrv.net/gimg/bikefor...d47bd89bab.jpg It should be noted however that my leg length is on the long side for my 5'9" height, so I am able to safely mount, dismount (and stand) clear of the frame's top tube. Note also that auxiliary brake levers typically require more-careful brake setup (and depend more on fresh brake pads and cabling, and on true rims) in order to offer ample braking power. |
Welp, based on my measurements, it looks like I have a 58cm frame. Looking at some charts, that's sized for someone between 5'8" and 6'1" :eek:
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Originally Posted by omg_my_butt
(Post 20535837)
Welp, based on my measurements, it looks like I have a 58cm frame. Looking at some charts, that's sized for someone between 5'8" and 6'1" :eek:
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Originally Posted by omg_my_butt
(Post 20535837)
Welp, based on my measurements, it looks like I have a 58cm frame. Looking at some charts, that's sized for someone between 5'8" and 6'1" :eek:
Your in luck that it's a 58cm, that would probably sell quickly. Always frustrating to have a great bike that's not the right size ;) But you'll be happier with a lower top tube for mounting/dismounting, and hopefully you're not too invested into the bike. It's starting to get late in the season, maybe sell yours in the spring, and buy a bike on sale now? |
Maybe we find her an Ironman over at the cult.
It's happened. :) |
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