I have a 95 trek 1220 still with the stock rsx group set. This bike will be used for unsupported tours with a Bob trailer. I want to replace the rsx with shimano tiagra 4700 or 4703. The difference between the two is the crank. Either a double or triple is available. with a triple my largest cassette option goes up to 32 teeth. With the double the largest is 34 teeth. So on a triple I can get a gear ratio of .94 and with a compact double I can get a lowest gear ratio of 1. For loaded touring in the mountains is having that little bit lower gear going to help that much or should I just stay with the double group set?

The '95 RSX crankset you are talking about replacing Has 26, 36 and 46 tooth chainrings, The proposed Tiagra crank would have 30, 39, 50 tooth chainrings and at least a 34t on the double version. So if you want lower gears, the newer Tiagra is not going to help you there. The RSX has steel mid and small rings for durability, I personally think that they are a really nice crankset. I would recommend just changing out the rear cassette for larger one.

I agree with the durability aspect however my chainrings are worn quite badly so unless I can find new rings (I dislike putting used parts on my bike unless absolutely necessary) I just want to switch to tiagra and have the 10 speed cassette.

If you are going to pull a trailer up mointain roads, you will want gearing that is as easy as you can get.
Personally, i would want gearing even easier than 30-32 for that style of riding.

Shimano triple cranksets are...limiting to say the least. The provide gearing that would make it difficult for many to ride mountain roads pulling gear day after day.

Bar end shifters, downtube shifters, or gevenalle shifters provide many options for gearing and increase the range.

What derailleurs and gears would you recommend to achieve even lower gearing?

^^^^ This. Also, seriously consider a mountain triple crankset and derailleurs and a 34 0r 36t cassette, cant have too low of gearing when climbing loaded,

44/32/22 with an 11-34 cassette. Using a mtn crank will require a shorter bottom bracket spindle, i.e., 103 mm.

The Tiagra front derailleur will work well with a Shimano Deore rear derailleur. It also works well with STI shifters.

If you can find 9 speed components, they will give you a nice range of gears, 4503 series.

Trentkln27, If you have a 7S cassette presently, you will need a new free hub to fit an 8S+ cassette unless you have a 4.5 mm spacer behind the cassette. Your other option is a new rear wheel or a wheel set.

Doug64's drivetrain is typical of what will be needed to achieve the gearing you'll use while touring; a mountain bike's crank set and RD. You may need to keep your FD if you have less than a 12T difference between the middle and outer chain rings.

Brad

The Tiagra cranks changed from the 9 speed versions to the 10 speed ones. The 10 speed ones changed the bolt pattern that unfortunately limits the smallest granny gear to 30, earlier versions had a diff bolt pattern that allowed changing it to a 26.
I am not super familiar with crank sets, but there are other 10 sp bikes out there that use cranksets smaller than 50/39/30. A good knowledgeable bike store can give you some options.

also, concerning changing your old chainrings to new ones, again, you would have to get informed info about what requirements are needed for 10 sp chains in terms of what chainrings you could buy and use on your existing crank. In our household we only have up to 9 speed, and I do know that early 90s 7 speed chainrings work fine going onto 9 sp cranks, I put an old 28t granny onto my wifes 9 speed bike 3 or 4 years ago and it worked fine.

re gearing, I am more familiar with "gear inches" for figuring out if a given gearing is low enough from my experience carrying a full load up mountains, but without getting into numbers, using a triple that has a granny of at least 26 and a rear cassette of at least 32 is just going to be more enjoyable for you and your knees.

and dont forget, there are mountains and there are mountains. Some mountain roads have reasonable gradients that go on for ages, others have short, really steep bits that are a real bugger.
Unfortunately, until you have toured loaded up mountains with a given bike+load weight on a given gradient, you won't really believe what we are saying here.

Yes I know about the free hub issue going up to more speeds and I do have a wheel set choose already. But I will find a MTB crank to bring the triple gearing down and switch cranks when I'm not on tour. Otherwise the tiagra has a big enough gear spread on the cassette already

A mtn bike crankset has been mentioned and thatd be paird with mtn derailleurs.

I diverge a bit from that, but i also dont ride thru mountains. If i had the interest and time to ride across the country or continents or whatever, i would not use what i currently use.

I like 48-38-26 triples. These are incredibly common on ebay as cranks from 20-30 years ago were set up for gearing about this type. You want new, which is understandable, so look into Sugino cranks. XD500, XD600, and XD2 are a few of the common typed you will see online.
The 26t ring can be swapped out for a 24t ring very easily and for about $15. That gives you even lower gearing.

Pair it with a Sora triple front derailleur or something like that. IRD makes a nice FD for these types of triples, though expensive.
The rear derailleur can be a Deore long cage or if you are willing to go used, a Deore XT long cage thats 9 speed or less.

9 speed mountain rear derailleurs work perfectly with road shifters and give you more chain wrap as well as a higher large cog in the rear.

The Sora FD is basic but it has the range to shift the setup and its a front derailleur...there isnt anything elegant to what they do. They shove a chain back and forth.
It wont shift like STI, but you also get gearing that(for many) allows for comfortable riding.


The shifter types i mentioned earlier- bar end, gevenalle, or downtube will all handle sifting very easily.

This isnt as tidy and elegant as all tiagra and STI. But its an approach that will get the job done with comfort.

I like the triple crank setup i mentioned because i can still ride the 48 ring when my bike is unloaded or when im with the wind or downhill. A 44-11 setup, i think i would spin out more often and be annoyed.

I just received gevenalle shifters last night for a bike im building (not touring). They are really cool and unique. Just food for thought.

I got mine a few weeks back but have been so busy with other stuff, I still havent put them on the bike yet....

I was looking at the shimano website to look at specs on MTB cranks. I know mountain bikes have a different width bottom bracket shell than road bikes but anyway the new shimano mtb cranks look like they have the 4 bolt pattern. Do you thinks I could get the rings and fit them to a newer road crank?

I have a 1994 Trek 1220 (the only year with down-tube shifters and not STI), and an 8-speed Jamis Aurora that I when through the same exercise that you are with gearing.


First off, you probably don't want to try to go with more cogs in back. This would require a new wheel, and more problematic the spacing of 8,9,10 speed wheels is wider and it not recommended to spread an aluminum frame. Also, you would need new shifters.


A 32 cog Rear cassette with require a long-cage derailleur. You may be able to go bigger than 32T, but with 7 gears to work with, and to maintain good shifting I would not go bigger than 32T.


The way I see it you have three viable options for the crankset.
1. Replace the rings. I like 24,36,48. the 24T cog with a 32T ring would be good-and-low. If you shop carefully these need not be expensive. I bought my Sugino 24t ring for $15.
2. Replace the crankset with a Sugino 8-speed set (models were in another post above).
3. Go mountain, which is what I did. It will require a narrower BB, because mountain cranks are designed with different spacing. The road set on my bike was 113mm, I had to go with a 103mm from Sunlite. This gave me the optimum 50mm spacing. you will end up with a 22T granny by doing this.


#3 sounds appealing, but I do not recommend it. Here's why:
It is very good when climbing a very steep hill, but the rest of the time the gearing is less than optimum. Lots of double-shifts between rings and less that optimum chain-line. I end up rarely shifting into the lowest combination. Also unless you have a crankset already, this is the most expensive to do.

Just to clarify too- those Sugino cranks can run as part of a 9sp drivetrain without issue.

I threw mine on within 5min of getting home.
...and now they will sit like that until other things arrive over the next few weeks.

I was very surprised they dont have the Tektro RL520 hood shape.
They are the R200 levers. Not sure how i hadnt realized that as i looked at them obsessively online for months.

My trek is already spaced out to accommodate up to an 11 speed cassette with proper hub. And a new group set would come with shifters. If I run the biggest tiagra cassette and then put an mtb crankset on for the time I'm actually touring I think that I can get the best out of both. The tiagra cassette gets to a 32 tooth low gear and paired with an mtb crankset that would achieve the gears you guys are suggesting but then I can switch cranks in the plains to get extra speed on the flatter parts of the country or when I'm riding around where I live

I see what you line of thinking may be... some say that early to mid 90's frames should be 128mm to accommodate either 126mm or 130mm (I read that 11 speed hubs are 131mm). I measured my frame (1994 1220) out at 126mm, actually maybe a 1/2mm under that). It could be that being a year newer yours is different. Is putting a 130mm wheel into a frame spaced for 126mm going to cause issues? If you have done your research and are comfortable with it go for it.

I should measure my frame but the shop I bought it from said it had proper spacing and I really trust the mechanics there

I just took a look at mine and they do have the rl520 shape, I did order 9 speed long throw ones so that perhaps was the difference?
Having been really happy with the fatter hoods of shimano sti, specifically 6 year old tiagra ones, I do find these kind of narrow, but will really only know how they are riding with them when I actually do the switchover. The bike presently has butterfly bars on it, and I have been planning to do other stuff to the frame, so this explains putting off the project. Holidays and work also have played a part and I am riding other bikes, so its been put on the back burner for now.

I'll start up a Gevenalle thread once I have them on and get some riding with them.

back to the topic, so Trent, what sort of shifters are you thinking of getting?

**edit--oops, you already said you wanted to go with the 10 spd Tiagra...I was thinking only of the Tiagra crankset.

The BB she'll does not usually differ between road and mountain. What differs is the chainline. Road setups are usually designed for a 45-46 mm chainline. Mountain setups are designed for 50 mm. Bottom bracket shells are usually 68 or 73 mm. It is the length of the spindle that is changed to attain the desired chainline.

If that's the case then with a hollowtech bb can I somehow grind at the axle on the MTB crank to make it shorter and work with a road hollowtech bb? Or should I just stick to using square taper bottom brackets?

Square BB, IMO they offer a wide range of options. If you go the mountain crank route, an 103 mm BB will usually give you the correct chainline.

Road FD and shifters work well with mountain, but there needs to be a 12 tooth difference between the large and middle chainrings.

A 44 tooth chain ring combined with an 11 tooth cog will give you 28 mph at 90 rpm. Most folks on tour do not reach those speeds unless going downhill or one heck of a tail wind.

The 44/ 32/22, 11-34 combination mentioned above works well when you get into the mountains. Last week my family completed a tour in British Columbia, Canada where we encountered a lot of 1-3 mile hills of 8%. It was the Selkirk loop. We were all glad that we were running mountain bike gearing.

Alright guys I appreciate all the feedback and I think I'll run full tiagra until I go on tour. Then I'll eqqip a mtb crankset and square taper bb and put mtb derailleurs paired with down tube shifters and use the tiagra levers as brake levers