Single Speed crank dilemma.

[al-fresco]

Here's the problem... I have an old Saracen MTB that I want to covert to SS as a 'ride to the pub' bike. So I ditched the dérailleurs and rear block, pulled off the crank to remove the 2 unwanted chainrings and... they're riveted on. No problem, there's another old MTB in the garage - I'll take the cranks off that... damn me - those chainrings are riveted on too. As it happens I also have a good MTB frame and crankset that I was saving for when I knew what I was doing. Yes, that has removable chainrings but, wait a minute, it's not a straight forward square taper fixing. So, I've checked on line - single speed cranks are HOW MUCH???

OK - so I'm looking for a cheap solution (£20?), square taper cranks and, say, a 36 tooth chain ring. (Is it possible to drill the old rivets out and fit bolts perhaps?)

And, while we're on, I'd like to ditch the old combined shifters/brake levers for a pair of basic levers that will operate V-brakes. Would second-hand BMX stuff do?

 

[Zoiders]

BMX levers won't give you the correct cable pull in most cases.

You can seperate/unbolt the shifters from the levers on some older shimano STI set up's, worst case scenario is a hack saw and file for some of the Alivio and STX-RC models.

You can drill the rivets out on some chainsets, you will have to check which ring the others ride upon though to see which one will remain on the crank arm once the rivets are gone.

 

[biggs682]

why not just leave the unused rings on !

extra weight wont make any great differance

 

[al-fresco]

BMX levers won't give you the correct cable pull in most cases.

You can seperate/unbolt the shifters from the levers on some older shimano STI set up's, worst case scenario is a hack saw and file for some of the Alivio and STX-RC models.

You can drill the rivets out on some chainsets, you will have to check which ring the others ride upon though to see which one will remain on the crank arm once the rivets are gone.

Thanks for that - I'll have a look and see if the ones I don't want can be drilled off. My V-brake levers are in a one piece molding with the gear shifter housing. They'll do for the moment but I'd like to replace them.

why not just leave the unused rings on !

extra weight wont make any great differance

I did consider that... but I didn't think it would look very good. (Even by my grungy standards!)

 

[GrumpyGregry]

ebay is your friend. You'll get some cheap second hand V brake levers from Avid or Tectro and a square taper Alivio, or similar, triple chainset you can remove the rings from for less than £25 if you are careful.

 

[al-fresco]

Thanks guys, drilling the rivets left me with a crank with a 40T ring - ideal for what I need, I'll leave the shifters in place for the moment while I get the rear wheel re-dished.

 

[TheDoctor]

Another option would be the cheap Stronglight chainset that Spa do.

 

[Jezston]

Another option would be the cheap Stronglight chainset that Spa do.

I've seen them, and other similarly cheap Stronglight ss chainsets about. Stronglight afaik are pretty reputable, and a spec of around 450g is pretty acceptable.

There's got to be a catch, right?

 

[TheDoctor]

I'd have thought so, but I've not found it yet...

 

[tyred]

There's got to be a catch, right?

They are swaged and therefore perfect for SS freewheel but will eventually break if you use them for fixed and do a lot of leg braking.

 

[Jezston]

They are swaged

They are what what now?

 

[PpPete]

Bending the metal up inside to join crank and ring - no chunky forged spider to spread the load.

 

[tyred]

The chainwheel is basically riveted to the crank arm and if you apply back pressure, it becomes loose and slips over time. I learned from experience. Mine was an old steel chainset so I just welded it up again but that's not so easy with alloy.

See Sheldon's glossary entry on Swaging (near the bottom).

 

[Jezston]

Aha, cheers. I shall avoid such cranks then.

 

[tyred]

There would be no problem so long as the bike has a freewheel.