Using Sugino/Spa triple crankset as double

[Ugo51]

Hi guys,
I am considering buying the Sugino-style crankset from Spa Cycles. Can I can use the triple as a double, provided I choose the right BB spindle length to have the correct chainline?
I might want to switch to triple later on (I use friction shifters, so I would only need to change the derailleur), but I wonder whether the crank risks to interfere with the frame if I use a BB with a shorter spindle.
It's not an expensive crank, but would be sad to buy the triple to then find out I cannot use it as double.
Thanks!

 

[kermisking]

I live quite local to Spa it's a great shop . I have used Campag triples with the granny ring left off many times to make a compact double square taper that I use on road bikes . the triple axle for these chain sets was between 124mm to 132mm in length which seems very long to me being a roady mostly not a mountain biker . The correct length spindle I used with the double set up was 102 mm which is a lot of difference .
Someone on retro bike should know what will work bottom bracket wise with a Sugino -Spa crankset .
It might mean having two different length bottom bracket spindles to suit double and triple .

 

[OldFatTi]

Hey Ugo I’ve got a fair bit of experience with this chainset - what bike is it going on and what ratios do you want to run?

 

[Ugo51]

A vintage Peugeot.
I'll keep my 34-50 ratios for the time being, but it would be nice to have the option to switch to a 3x setup when I take the bike to the hills

 

[pigman]

A vintage Peugeot.
I'll keep my 34-50 ratios for the time being, but it would be nice to have the option to switch to a 3x setup when I take the bike to the hills

Don't forget you'll need a triple front mech too when that time comes

 

[Ugo51]

... (I use friction shifters, so I would only need to change the derailleur)...

Thanks.
I've got that sorted

 

[OldFatTi]

Well all frames vary for chainstay clearance, and bear in mind the crank bolt torque will affect how inboard it sits, but I’m successfully running one on a modern roadie frame (30c rear tyre clearance) that’s likely wider than your Pug, as a 24-36-46 triple, on a Stronglight cartridge 103mm JIS BB. I personally couldn’t run a narrower BB axle as the granny ring would hit the stay and the crank arm itself will definitely foul the BB cup. You’ll likely be in the same boat depending on the design of the BB cup…

Maybe a little longer than 103mm would be more sensible, but you certainly can go less than the usual 110/113mm axle.

 

[Frankenorange]

. The difference is the double does not have the granny ring bolt holes drilled and tapped, but otherwise is the same casting. I found the suggested axle lengths to be good but i would suggest using a BB with adjustable chainline a smart move. The machining and tolerances aren't brilliant. The tapers fit well on Shimano axles.

Apart from the bcd difference the main difference is the RD2 cranks may sit closer to the chainstays than the XD2, on the same length axle. That was my experience anyway BUT i did change BB make, at the same time, and how far cranks go on to axles can vary.

One thing i have noticed, with both types i have bought , is there has been an arm that is a little out of line with the others. if you use thin chainrings you will get a little kink in the chainring as it turns.
Thicker chainrings seem to pull it inline with the others and the tab that the chainring sits on can tolerate a tiny tweek with a suitable tool. It has only been about a 1mm error on the worst crank. This i have had on the three cranks i have bought(2 XD2 and 1 RD2) and all were new.

Also; both cranks flex quite a bit so anything less than about 3mm, between the inside of the arm and the chainstay, you will might get contact if you give it some sh!t. Will depend on the frame BB stiffness, BB make etc but just a heads up.

They are pretty good for £30 though.

 

[Ugo51]

Thanks.
I must say I don't like that. I can live with a bit of flex (I have puny legs in any case), but the out of line arms would be a disappointment.
Let's see.
For £30 I can't expect high quality, I suppose. It's not easy to find a black 165mm crankset, 110BCD, for square taper BB, so I didn't have much choice.

Just to add to your info, for any potential future reader of this thread, a major difference between RD2 and TD2 is the BCD, 130 vs 110mm

The XD2 is different from the other two in that it has a hidden fifth arm (a design that I find aesthetically unpleasant as well as not very practical)

 

[hamster]

I've bought something like 5 over the years and never had a squiffy alignment issue. Shimano cranks invariably were worse in my experience. (TA best, then Campag & Middleburn, Sugino and finally Shimano last.)