voyager1

Hi everyone!

I have a 1991 Trek 1200 that I am thinking about updating. I plan on using it as a backup bike. With the miles that I have put on it, I am probably be getting a new chain for it. I figure this might be a good time to do a little updating. I want to keep it 7 speed and DT shifting.

So my question is this. I pretty much never use the big chain ring, is that something that is easy to make for more comfortable riding? The crankset has 53/42 up front and the cassette is 13-23.

I understand I can’t make this bike like my Domane, but I can’t imagine riding this 1200 in the 42 almost exclusively is probably good for that ring.

ETA: Looking at the Vintage Trek website, would converting this bike to a triple be a better way to go?

thinktubes 

I really like 48T for the big ring. Works very well in flat/windy chicago.

C9H13N 

You can source new chainrings and change the cassette to go a little lower. 50-39 x 11-28 might be enough for you.

Swapping for a triple is going to require a new bottom bracket and rear derailleur in addition to the crank.

Reynolds 

It all depends on the grades you expect to ride.

RobbieTunes

50/38 is possible if it’s 130BCD.

voyager1

What does 130BCD mean?

voyager1

There are some pretty steep (but short) hills around here. Everything else is just rolling hills it seems.

C9H13N 

BCD is bolt circle diameter, for the chainring mounting bolts on the crankset. Your bike is likely 130 BCD if it has the original crank.

The smallest chainring that will fit 130 BCD is 38 teeth. 39 tooth rings are much more common.

The Golden Boy 

Bolt Circle Diameter-

The diameter of the bolt pattern on your cranks... That kind of determines what size crank rings you can have... So a lot of cranks on older racing bikes have a 144 BCD- because of the BCD- the smallest ring that will fit on there is a 41 (if you can find one).

The 130 BCD will allow for a 38.

A 110 BCD will allow for a 33 (if you can find one).

Most of the old triples were made with a 110/74 BCD- a 110 for the 2 big rings and a 74 drilled into the arms to allow for the smaller "granny" ring.

Salamandrine 

Should be an RX100 crank, which is 130 BCD. If they are standard and not anything oddball (I can't remember) you should be able to swap out the chainrings for 38/48.

However, I would suggest simply replacing the 7 speed cassette with a wider range one, and getting a long cage rear derailleur. It's simpler and more effective, easier and typically cheaper. All you need is a cassette, chain, rear derailleur.

voyager1

Okay I will check into that, but I was thinking this bike might have a freewheel vs a cassette?

Salamandrine 

If it's a freewheel it's the same deal, more or less. Swap that instead.

canklecat

I've switched my Centurion Ironman around for windy or hilly conditions. It came with 52/42 chainrings and 7 speed 13-24 freewheel, but I usually ride it with 50/38 Vuelta chainrings and 13-28 SunRace freewheel. Works great. 52/39 worked fine too.

I used 52/42 Biopace chainrings on one road bike for a year and the 42 Biopace felt kinda like a 39T circular small ring. For me, the eccentric chainrings helped a bit. Some folks don't like them.

One of my carbon fiber bikes currently wears 53/39 and even with the much lighter bike some rides the 12-28 isn't quite enough for climbs into headwinds. I try to avoid grinding but occasionally bog down. I'd switch to a compact crankset but it's expensive to replace Ultegra so I'm keeping it for now.

due ruote 

https://www.sheldonbrown.com/gear-calc.html

You might find it helpful to play around with this. Put in the data for your other bike, figure out what range of gears suits your needs. For instance, if you never use the 3 lowest or 2 highest gears, omit them from your target range. Then plug in chainring and cog values for the Trek until you find what will work to get you close to your ideal range.

pcb 

This below, 100%.

Your bike, your legs/lungs, your terrain, your headwinds, your speed, your mileage. You have to figure out what gears you have, which you don't need, and which you don't have that you think you might want. We can tell you what works for us all day long, but we ain't you.

Your first order of business is to figure out what kind of gear range you want/need to cover. Everything else flows from that.

Once you have the gear range figured out, then you can start looking at how to get those gears with the minimum of disruption/cost, unless you want buy all new stuff and wrench around a lot. Nothing wrong with that.

Nothing wrong, either, with only using the 42t ring if that's all you need. It'll wear out quicker, but you can replace it when it wears out. Your 53t ring won't hold a grudge against you. I know I just said that just because something works for us, doesn't mean it'll work for you, but I've got a bunch of multi-geared bikes with single chainrings. I've kissed many a front derailleur goodbye, for good. Front shifters, too. It's a valid lifestyle choice.

If you never use the 53t big ring, that tells me your 42/13t is probably high enough. On a 700c wheel that's about an 86" gear. If you never spin out with the 42/13, or if once you're going fast enough in an 86" gear, you're basically coasting downhill, then you don't need anything higher.

Your 42/23t low is about 49", which isn't considered an easy gear for steep climbs. It was a low gear for racers back in the day, but not so much for non-racers.

But like the 53/13 you never use, if the 42/23 is low enough for you, then you don't need to change anything. Just ride the 42. If you have issues with the chain rubbing the 53t ring a little when it's on the 13t cog, you can replace the 53t ring with a smaller-diameter chainguard-like ring.

If you decide you want lower gears, the easiest way is changing the 42t chainring to a 39t or 38t, but that won't get you a lot lower, and then your high gear gets a bit lower. Better to go with a wider spread in the rear. 13-28t might let you keep your rear derailleur, 13-30/32/34t would probably mean a new rder.

thinktubes 

Bolting-on to what pcb said, when I was running a 53T, I would only use the highest gears on large downhills (scarce around here).

When I switched to a 48T, I use almost all the gears in various situations. I could probably bump up to a 50T, but the 48T seems like a sweet spot.

Overall, the bike is geared 48/39front, 11-23 back. I've done some hilly rides in Wisc. And it worked well.

mstateglfr 

get a 110/74bcd crank. They are very common on ebay or at bike collectives(ours at least). Use the outside 2 ring spots and ignore the small 3rd granny location. You can set up gearing that is much more valuable for your style of riding.

53/42 and 13/23 is completely absurd gearing for many and current enthusiast road bike gearing shows how poorly spec'd road bikes were 30-40 years ago for most cyclists.
Get a 46t or 48t large ring. Then get a 34t small ring. bolt em on and you have gearing that is for sure more useful.

bark_eater 

My "road bike" is presently set up 48t-36t with a 6 speed 14-28t freewheel. It is primarily an exercise machine and next spring it will go to a 50t-34t and a 6speed 14-24t freewheels just to be able to push a little harder. That said I live on the coastal plains so hills are the exception. I ended up happily tootling around on my touring bike all summer, putting in 70-100 mile weeks, rarely coming off the 38t chain ring with 7 speed 11-32t cassette. I recently picked up what will be a 40t-27t crankset which I think would work with a 7 or 8 speed 11-25t cassette.

79pmooney

Your crankset may or may not say what the BCD is. Accurately measuring axle center to chainring bolts is tough. But an easy way to document what you have is to measure chainring bolt to the next chainring bolt and multiply by 1.70.

Edit: I second the love of the 110/74 cranksets! All my geared bikes have them. (And yes, I kn ow all about being a "hard guy" I trained and raced a 144 BCD 54-42 X 13-19 in New England except Smuggler's Notch - a 23 and Mt Washington 28 X 21.) Now, if you have a 144 BCD cranset you can put on a 41 tooth chainring. Campagnolo made them. I have heard about them since the mid-70s but never actually seen one. Ran into someone with two last year, They do exist! And more common than hen's teeth.

John E

Look at your 42T ring. If the gaps between the teeth are almost down to the bolt circle, you have a 144mm BCD, and the smallest you can go is 41T, assuming you can find one.
If that is the case, just replace that 13-23 in back with a 14-24, or something larger if your rear derailleur can take it. For a 2x6 setup, I use 50-42/14-26 or 46-38/13-25 for a 1.5-step, or 45-42/13-26 for half-step. A low in the low 40s and a high in the mid 90s provide all the range I need.

Salamandrine 

That's interesting. I've never seen a campy 41T. It must be from the last few years of NR/SR. With a traditional bushed Regina type chain, 42 is the minimum. The relatively high side plates would hit the spider if you tried to use a 41. It only worked when people started to switch to sedisport chains.

I remember some people running Avocet 41T rings. Avocet/Ofmega cranks had a notch on the top of the spider arms, to make room for chains with taller side plates. How's that for C&V cycling trivia.

Anyhow, I looked up the spec for a 91 Trek 1200, and it's supposed to have an RX-100 crankset, which is 130.

pcb 

I'm not sure I've ever seen a Campy 41t chainring in the flesh, with my own eyes, but I have seen them offered for sale. They definitely were manufactured and do exist.

You can get a 144bcd 41t TA ring fairly easily through Peter White, or perhaps some other vendor who carries TA product. It's in TA's Competition line, 144bcd rings to fit that old standard. I have no financial or other tie to Peter White other than sending him money every now and then for cool chainrings, and thanking him for carrying cool chainrings if I see him at a show. He is known to be a little dry and curmudgeonly, don't say I didn't tell ya.

I'm using one on my '71 Raleigh Pro track bike, primarily because I need to keep the wheel/axle fairly far back in the dropout/end to get enough tire clearance, which I couldn't do with a 42t and get the gearing I wanted. I'm using it in the outer position, and the chain is leaving grease marks where it contacts the top of the spider arm, but no gouging yet. Though I've only got about 50mi on it so far.

What I've heard/read from others is that they just ride the 41t, and eventually it removes as much metal on the spider as it needs, so it doesn't seem to be necessary to proactively file the ends.

Peter White's chainring page, hopefully going straight to the TA Competition rings:
https://www.peterwhitecycles.com/ta-...hp#competition

Here's one on ebay, in the UK, not currently in stock:
https://www.ebay.com/itm/192204585545

Gratuitous '71 Raleigh Pro Track pic with 41t TA Competition ring:

due ruote 

One more point about the gear calculator and figuring out your target range, etc. If you have a “cruising gear” that you occupy much of the time, make sure you end up with a gear that’s at least close to it. For example, I am in the flatlands and spend a lot of time spinning gears in the low 70’s (gear inches). If I had a bike with gearing that went from 65 to 75 and nothing in between, I wouldn’t be satisfied.
Ideally, your cruising gear will also have a good chainline.

hermanchauw

i have a bike that had front 42-52, rear 11-28. Never used the big ring also. I converted it to front 22-32-44, rear 11-32.

Then i got tired of shifting so many times. I converted it to front 26-38, rear 11-40. Never use the small ring, but it's there just in case.

bikemig 

The idea of finding a used 110/74 bcd crank and running it as a double is a good one. That will keep your costs down and you can run as small as a 34 tooth on the insider. Or you can pick up a 110 bcd double but that will be more expensive; like this for example

https://www.planetx.co.uk/i/q/CSHOCN...retro-crankset