SDHawk

Hi, I'm considering this one. Converted to cruiser HBs but all original otherwise incl 600 Arabesque group. Seller says needs new tires and tubes. Worth $100? I'm trying t get better pics.

bikemig 

This is a full chrome moly frame, right? Sure it's worth $100 even in today's soft market.

SDHawk

To follow-up, I bought the bike. Not sure what I'll do with it, but I couldn't resist the great condition and cool old 600 components.

Kabuki12

Is it your size? If so, it should be a decent bike . Enjoy!

SDHawk

Yah It's my size though the cockpit is a bit tight with the cruiser bars. I may need to experiment there.

Thanks for the endorsement. It seems pretty nice, tho I haven't ridden except test ride. In researching, I read that Miyata made frames for Univega around this time, and that this Gran Rally might be equivalent to a 912. Does that seem feasible?

SurferRosa

It's definitely a Miyata frameset, but I doubt it's exactly a 912. Though, the frame material is on the same basic level. And the Gran Rally fork may even be a little nicer (chromoly) than the one that came with the 912, at least in the early part of the '80s.

SDHawk

Hi again, I have a couple of questions. I rode the bike for a few miles and I like it except the gearing is quite difficult for me. I live in a hilly area, and am spending a lot of time in the easiest 3 gears. And I know there are bigger hills where even the easiest gear might not cut it.

The front rings are 52/39 and the rear is a small, tight 6-speed. What's my best option? I hate to mess with original but I need to in this case.

Also, the tires are 27 x 1 1/4 and need to be replaced due to sidewall cracks. I think there is room for a bit wider on the frame. Should I go a bit wider? I see 27 x 1 3/8 are available. Would the rims accept that?

Appreciate any input!

SurferRosa

The freewheel doesn't look that "tight" to me. What's the biggest cog, 26t?

One issue is the derailleur cage is short, which will limit your chain wrap. If it were a little longer, you could go with a Sunrace 13-28t, like this one:

https://www.ebay.com/itm/175249444991

That derailleur will still service the Sunrace 13-28. But with the 52/39t up front, you will be limited in the low gear selection when using the large 52t ring. That can be an acceptable trade off, but you need to ride knowing what gears you can use and those you can't.

I would stay with the 1 1/4" tires and buy Panaracer Paselas online. Check eBay.

Schweinhund

Put that seatpost down, there's only about an inch in the frame.
I have a 1984 Gran Rally in a 63, yours is much closer to my size.
Great bike.

SDHawk

Thanks. Yah, the biggest cog is 25 or 26. Would a 28 feel much easier? Even if it did, I'd rater not ride in the easiest gear so much. I guess I'm just weak haha.

What about changing the chainrings? It seems like if I went from 52/39 to something smaller it might be more effective and not hinder RD performance. What do you think?

No worries, I only had it up for cleaning. I ride with it much lower Btw, if you can ride a 63, this would be too small, no? It's about 50 I think.

Schweinhund

lol, you ever seen a preteen ride a ten speed? thats what my 5'5" body looks like on that 63. A 50 is much closer to what I ride.
I bought it for the 600 group and the pristine paint

bikemig 

+ 1 on this. You could also run a 110 bcd crank. The OP likes working on old MTBs. A shimano square taper triple can be run as a double and will likely work fine on the existing bottom bracket. That way you can run 50/36 or even 50/34 rings and get some better climbing gears.

zandoval 

If not going to take it then send it my way...

SDHawk

Thanks very much for the advice. I have more questions... as you noted I'm more familiar with old MTBs

When I look for 50/34 cranks or chainrings online they all seem to be for bikes with 9+ speeds. Any ideas for 50/34 that could bolt onto the existing 600 cranks and work with the 6-speed setup?

As for the MTB idea, would the triple fit onto the current spindle? Would the FD then use just the outer 2 rings of the triple?

bikemig 

That's likely the original cup and cone BB for that shimano 600 crank. It should work with a shimano triple crank run as a double. I've done that with good success. Simply use the outer two positions and you can run as small as a 34 on the inside giving you a "compact" crank.

Do you have a shimano MTB 110/74 bcd crank in your parts bin? I'd just use that crank with the rings that came on it; simply remove the inner chainring. Otherwise you can buy new 110 bcd rings to get the gearing you like. You don't need to buy expensive rings since you're running friction. These Origin 8 rings on Amazon are $30 each; you might be able to find cheaper if you shop around,

https://www.amazon.com/Origin8-Alloy...8-5&th=1&psc=1

plumberroy

I picked up one a few years ago at a yard sale. For $20 all it really needed was cleaned up, lubed up and new cables . Since it was a 48cm I fixed it up for my daughter .

roadcrankr

Picking up three teeth on the chainrings roughly equates to picking up one on the rear cog.
No doubt, you investigated and handled the potential rust inside the seat tube.
If it migrated to the bottom bracket shell, it could wreak havoc from within.

SurferRosa

That might work fine with a different rear derailleur, but not with your existing one.

Short cage rear derailleurs need a more limited differential in the chainring size. 10t (52-42) is optimal. 14t is doable on a more narrow cluster, like 14-25t. But if the gap between rings is more wide, a short cage rd will need an even more narrow cogset.

Search for an online gear calculator and plug in some teeth counts to understand how slight changes in rear cogs affect available gears more than chainring size.

SDHawk

Thanks again, great stuff. I checked out a calculator and tried different combos, keeping in mind that the difference in front rings should be 10-12t.

First , I checked the current freewheel and yes it's 13-26. SurferRosa , I saw your idea about increasing to 28t but I don't love the idea of some gears not being usable when on the big ring.. Also 28t helps some according to calculator, but I don't think it's enough (the low gear ratio went from 3.0 to 2.8)



So I focused on the front rings using 44/34 and 42/32. bikemig the only MTB I have lying around are 48/38, which won't do much where I need it.44 34
13 6.8 5.3
15 5.9 4.6
17 5.2 4.0
19 4.7 3.6
22 4.0 3.1
26 3.4 2.6

Those ratios feel like they would be better for me and the hills. First, is going that small technically feasible with the 600 cranks? I'd like to keep the cranks and swap only the rings if possible. What else am I missing.... I'm sure there's plenty

bikemig 

The 600 crank isn't going to do it for you. That's a 130 bcd crank which means the smallest chainring is a 38 I believe. If you have a 110/74 bcd triple, the outer two are 110 which means you can run as small as a 34. You have a 48/38 on hand. You could buy a 34 110 bcd chainring and run a 48/34 to get the gears you want.

SDHawk

Thanks again, I'm learning a lot . I see now what you mean with 130 vs 110. I'm hesitant to put a mtb crank on... at least the one I have. It's old and heavy. Will keep it in mind though.

So as I was progressing through cleaning and tune up, I realized the BB was way too tight and there was some resistance. I'll clean up and dial in, maybe it will help. Wheels spin well tho the rear was out of true and had like 4 loose spokes. I'll probably clean and grease hubs too. I'm hoping that will all help.... we'll see.

SDHawk

Just a quick update. It's a bit easier to climb after I cleaned and adjusted the BB and hubs. I decided against wholesale changes because I don't want to break up the nice 600 group. I may go with SurferRosa 's original suggestion of a slightly larger freewheel, keeping in mind that I can't go too much bigger.

Here are a few more pics of the bike.