MikeHunt79

Ok, I've got an old 80's roadie bike made by Toyo Tiyama (or something like that), and it rides ok, but the gearing is a little too low for me. I was wondering how can I gear this up a bit?

It has a triple on the front, 26-36-46, which does the job ok, but it uses 6 bolt chainrings, so I might end up having to replace the crankset once the chainrings go, as I've never seen anywhere that sells 6 bolt chainrings. Now I've seen some shimano tiagra hollowtech 2 4403 cranks for sale for around £35 which I reackon would do the job as they will give 30-42-52 chainrings. Would this work ok, or would I have to get a new mech and other bits?

Now, the rear wheel uses a 5 speed freewheel, which has a range of 14t-28t. Now, If I was to rebuild the wheel with a cassette hub, would I be able to use an 8 speed cassette with a range of 21t-11t? Would a cassette hub from a MTB work or do roadie bikes have different spacing? I ask this because I have a few spare 26" wheels which have perfectly good cassette hubs on which I could use.

TallRider

If the chainrings are aluminum and in good shape, I'd keep it, and go with a cassette with an 11t small cog, as you're planning. I ran a 46/36/26 with 11-21 8-speed for the first 7 years that I had my good road bike.
However, I doubt that you can find 11-21 8-speed cassettes anymore. Maybe 11-28.

But if you're updating to a cassette hub, you may as well just go with 9- or 10-speed cassette, since you'll be buying a new cassette, chain, and shifters (the latter only if you want to go indexed-shifting) anyway.

Easiest thing for you to do, as long as you don't weigh too much and ride on at-least-good-condition roads, is get a Shimano 11-28 7-speed *freewheel* and add some spacers to your rear hub. You'll need to redish the wheel, and spread the frame slightly. But this is the way to get the gearing you want with minimal changing.
Downside of this is that the more speeds you have on a freewheel, the more axle is exposed between the bearings and the dropout, so the more chance of bending your axle.

ivan_yulaev

Nashbar has 8-speed 12x21 cassettes. 46x12 isn't too bad.

silversmith

Chances are that you have a very decent frame there. I suspect that is made by the same folks who make the frames for Rivendell's Atlantis.

John E

There are only a couple of standard 6-bolt BCDs: TA's 152 and Simplex's 157, often used with cottered steel cranks and 3-to-6-bolt adaptors. I find LOTS of listings for TA chainrings on eBay and occasional listings for 157mm rings. (Right after I bought the 1960 Capo and decided that 58(!)-45 / 14-22 criterium gearing was too tall for me, I found a pair of aluminum 157mm rings, a 49T and a 47T, on eBay.)

cyccommute 

If you replace the crank you will probably have to replace the bottom bracket also. Modern sealed bottom brackets are far better than the old cup and cone style anyway so this won't be a great loss. The only issue is if the bottom bracket is some kind of funky thread size. Considering the age of the bike and that it's probably a Japanese bike, you should have problems but one never knows. Have a shop check it when, and if, you buy a new crank. But as others have said, just use this crank until it wears out.



Cassettes are cassettes. An 8 spd road has the same spacing as an 8 speed mountain. I use mountain bike cassettes on road bikes (touring bikes) all the time. There isn't a problem there. The issue is with the rear triangle spacing (distance between the dropouts). For an 80s bike, it's probably 126mm. If you have a hub that is 130mm (typical road spacing now), there is enough flex in the rear triangle that you can probably just force fit a 130mm hub into the 126mm space. It will make changing wheels a bit tedious but it's doable (I've don't it a couple of times). If you only have 135mm hubs (typical mountain bike spacing now), you may have to have the frame cold set - bent- to conform to the new spacing. I'd try the hub to see if it can be fit in the space first before you go to cold setting. Path of least resistance and all that.

HillRider

You may need a new bottom bracket if you change the crank but, assuming your current crank is a standard (JIS) square taper, the old one might be ok. Your front derailleur may have to be replaced if the cage curvature is too much for the larger chainrings.

Your frame will probably have to be respaced for anything more than the current 5-speed cogs if it has 120 mm dropouts and for anything more than 7-speed if they are 126 mm.

MikeHunt79

I guess I'll keep the cranks then... The rings are ok, and when they do wear out, I can always get new cranks then.

Well, I never knew they made freewheels with less than 14t, but after looking on sheldon brown, they seem to do them after all. The only problem is, I can't find the 11-28 freewheel in the UK at all. Either I could get onesent over from the USA, or I could get the "megarange" one with 11-34 teeth in the UK. I guess if I did get the megarange I might need a new rear mech, but I'll cross that bridge when I come to it. Also, my axle is the solid nutted variety, so it should be ok... I'm sure with a 46-11 high gear will be better than my current 46-14. I'm sure I'll be able to fit it all in the frame with a bit of tweaking.

Also, my frame looks identical to the Miyata in your sig... It might even be the same model. What model and year is yours? I don't know what mine is, but I'd be interested to know. Also, I managed to snap the original forks on mine, which is a shame, as the frame and forks seem well made and light. Also, are you using a 130mm rear hub?