escuta

The bike arrived, finally, and it's in really excellent shape! Seems to have had relatively light use, as the previous owner said, and has been well looked after.

I have a doubt about tightening (and sorry if these terms aren't correct) the clamp on the stem to the steering column. The column (that tube rising up from the forks) is carbon and I've heard of carbon tubes breaking from clamps done up too tight. With the allen key, once it has been used to firmly close the clamp around the column, is there some kind of rule-of-thumb for tightening up from there? eg. 90 degrees more? The forks are by ITM.

The stem is an ITM Millenium - CNC ergal 7075. I don't know if it's possible to tell from this name what the clamp size is, as I wish to put on drop bars and will need to know. Later though I'll un-clamp the bars and try to calculate by measuring the circumference. There looks to be a shim around the bars which are a Syntace TT Tri bullhorn/aerobar combo made in aluminum - I've read that these can be 26mm at the stem mount but couldn't find anything definite.

The wheels are nice without any apparent buckling but seem to be stiff and don't run as freely as I imagine they should. I guess they need some lubricant. Can anyone please say what general type is best? For my simpler bikes I've always used Singer oil and WD40 for most things but realise these may not be ideal.

Somehow my post count dropped from 11 to 6 so I still can't post pics.

Cheers and thanks,

escuta

There is also some writing at the steering column end of the stem. "MIS. 120" on the left side of the clamp and "13 - 00" on the right.

ShannonM

There are basically 3 standard sizes for road bike handlebar clamp diameter. 25.4 mm (old Japanese bikes), 26.0 mm (almost everyone else except Cinelli and the French,) and 31.8 mm (newer bars for both road and MTB.) If the TT bars are 26.0, and there's a shim in there, that makes the stem most likely 31.8 mm. They might be 25.4... I remember a lot of aftermarket aero bars came that way, with several shims so that they only had to make one size and it'd fit everyone's stems. If you're lucky, the shims are marked, so you can just add them to the bar diameter and you'll know what the stem is. Measuring stem clamps is notoriously tricky, even with calipers.

I'll let others describe how to get proper torque on the steerer tube end of the stem, as I've never installed a carbon fork. But proper torque is what you need, since with threadless headsets the stem holds the whole front end of the bike together... if it's too loose, very, very bad things happen very quickly.

--Shannon

escuta

Thanks Shannon. I meant to post yesterday that I measured the the circumference of the bullhorn bar with the shim attached and it is 8.5cm. Dividing by pi gives the diameter of 27mm. I'm not sure how accurate that is but it's definitely not 31.8. So if I keep the current stem I can use 26mm bars and improvise a shim (I i don't want to remove the shim on the Syntace bars as it extends and is needed for the adjacent aero-bar clamps too and I will probably sell the bars as a set). I was thinking of trying sanded Coke bottle plastic for the shim - or Coke can metal if I can find some shears.

I did go for a test ride yesterday evening after tightening the steering column clamp very firmly. So far so good.

ClydeClydeson

One correction for ShannonM I believe 25.4 was the more common size on most bikes up until 31.8 oversize bars came out. Some Italian makers were still hanging on to 26.0, but mountain bikes and hybrid bikes and most non-Italian road bikes had 25.4 bars.

https://www.sheldonbrown.com/cribsheet-handlebars.html

SJX426 

Not relevant if new bars are purchased but Cinelli had two sizes, older AL were 26.4 and newer 26. 26.4 has a sleeve in the center.

ShannonM

Could be false memory, but I remember there being a shift from 25.4 to 26.0 for good road bikes sometime in the early 2000s, around the time when 31.8 was coming out for DH / freeride bars. Maybe it started with carbon and ultra-light aluminum bars, which needed the extra clamp area?

Or I could just be wrong.

--Shannon

cpach

I would also suggest just using the bar end shifters and levers on drop bars and not buying new shifters.

As for torquing the stem pinch bolts, the correct answer is to get a torque wrench and tighten to recommended torque (often 5nm). Otherwise, the next best thing would be to carefully bring the bolts up in torque evenly until you find the minimum torque that holds securely. But really just get a dang torque wrench.

icemilkcoffee 

The shift towards 26.0 for road bikes probably took place in the 90’s. The reason is drop bars went from simple rounded curves, to more complex compound curves when brifters became the norm. These compound curve bars are hard to maneuver through the stem clamp hole. It’s barely doable when it is the larger 26.0mm bore. Not feasible with the smaller 25.4mm clamp.

escuta

Ah, OK, I'd expected them to be more expensive but found an analogue one that's affordable (imported things are very expensive here at the moment!). Will send an image of it once my post tally reaches 10 (again), to see if you think it's junk. Cheers

escuta

I should now be able to post photos...

This one is the cheapest and my preferred option but only does 5 Nm:




The next cheapest does up to 12Nm:

ClydeClydeson

By the end of the 90s, 26.0mm bars were certainly the exception and not the rule. By 2000, the vast majority of stems on new bikes were the removable faceplate kind, so getting non-standard bar shapes through was not an issue.

My last job in a bike shop was 2000-2006 and the bars and stems on all the road bikes and mountain bikes we sold were the same 25.4mm standard, until 31.8 took over for the better quality bikes.

ClydeClydeson

ShannonM icemilkcoffee
From Sheldonbrown.com:

25.4 - "Standard I.S.O. size, used on most bicycles with drop handlebars.
Also used on older British aluminium upright handlebars."
26.0 - "Italian standard for drop bars, other bars made to fit Italian stems and some high-end aftermarket drop bars.
This is sometimes incorrectly called "road" size."
source: https://www.sheldonbrown.com/cribsheet-handlebars.html

The shift in the 90s was away from 26.0 and toward 25.4.

ClydeClydeson

ShannonM icemilkcoffee
OK, last post on this topic, I promise...

I looked further into the chart at Sheldonbrown.com and found the note for the 26.4mm size:

"Older Cinelli and Cinelli copies. Cinelli changed over to 26.0 mm in 1998."

Perhaps this is what you were thinking about?

icemilkcoffee 

All I know is- the nicer drop bars from that 90's to early 2000's period were all 26.0mm. ie. the lightweight T6 hardened drop bars were almost all 26mm, the carbon fiber drop bars were 26mm (and didn't grip well enough at that diameter), and most of the drop bars that had compound 'anatomic' type curves were also 26mm.
The road quill stems with detachable faceplates tended to be the 2 bolt varieties for some reasons. And these had a tendency to rock when you're pulling hard on the bars. I had a Deda style 2 bolt at one point, and it was rocking like crazy on climbs. The hinged stems did work well for this purpose, but I think single bolt stems were still the norm all the way through the end of the quill stem era.

escuta

Job finished! Found these 44cm Most compact bars. Very happy with the result. Super comfortable. I suppose the stem/bars could go a little lower but I don't really have much of a need for that, at present. The bar end shifters are very easy to use. The bars have a 31.8mm mount and I changed the stem as well. It's 10cm as opposed to 13cm, a much better fit for me. Thanks again everyone for the suggestions.

ClydeClydeson

Sounds like you had a 26.0mm stem and were assuming the bars were also 26.0mm, but they didn't fit properly in the stem..

ShannonM

That's a properly-sorted bicycle right there!

About the only thing I'd change is to move the bottle cage to the down tube. Much more convenient to grab, looks way mo betta.

As to bar height, if you find you want to lower it, you can. Just don't cut the steerer unless you're 100% sure... they're really, really hard to stretch once they're cut. The best way to figure out your ideal bar height is to ride in the drops on a flat road at a steady effort, preferably with no wind. If it hurts, it's wrong.

--Shannon

escuta

I meant to ask why you suggested fiction mode rather than index. Reliability and/or ease of adjustment? At the moment they're set to index mode but on the last ride I noticed a bit of noise when on the lower gears.

ShannonM

I wasn't suggesting riding in friction mode, although you should probably try it just because it's there and friction shifting has some lessons to teach about how bicycle drivetrains work. And who knows, you might find that you actually enjoy friction shifting your bicycle. There are some weirdos who do. (Yes, I'm a weirdo.) There's a tactile, feedback-y nature to it than can be quite entertaining and satisfying on its own terms... sort of a "make it more difficult to make it more interesting" kinda thing.

What I was referring to was the fact that bar-end shifters have a friction mode at all, which integrated brake/shift levers do not. As reliable as modern indexing drivetrains are, (and that's very, very reliable,) the existence of a friction mode can make the difference between riding home on a geared bike and a singlespeed. It's happened to me a couple of times over the years.

"Limp mode" is a good thing if you can get it... it beats walking home, even if it's kinda lame.

--Shannon

escuta

I see. When I said new to road bikes in the opening post, I should have said new to road bikes after a significant pause. I rode a rather heavy 10 speed 'racing bike' with friction gears to school, up until 1982. :-) All the best!