Single gear bike

darrell1967

Hi,
I’ve got an old Dolan frame and some odd parts including a Tiagra 4600 chainset, brakes and 10 speed cassette.

Can I run this without a derailleur with the chain on the 6th cog for example?

I’m thinking of building a simple bike to go up the gym on.

Cheers

shirley_basso

The tricky part is getting the chain the right length and tension so it doesn't bounce out the sprockets.

The simple solution is to use a chain tensioner - like a rear mech but doesn't move up and down, just the spring bit.

darrell1967

I’ve just nosed at tensioners on eBay. Only £20.

Why is it hard to get the chain length correct? It was straightforward on my old BMX or is it because of the drop-outs??

elbowloh

darrell1967 said:

I’ve just nosed at tensioners on eBay. Only £20.

Why is it hard to get the chain length correct? It was straightforward on my old BMX or is it because of the drop-outs??

If you have a tensioner it shouldn't be hard to get the chain length right.

darrell1967

elbowloh said:

darrell1967 said:

I’ve just nosed at tensioners on eBay. Only £20.

Why is it hard to get the chain length correct? It was straightforward on my old BMX or is it because of the drop-outs??

If you have a tensioner it shouldn't be hard to get the chain length right.

Will it work ok to go from the 4th or 5th sprocket to the chain wheel??

imposter2.0

You haven't said what the frame is, or whether it has vertical or horizontal dropouts. Unless you are running a straight chain line, it is likely to be at best unreliable, or at worst, unworkable.

darrell1967

Its got vertical drop-outs.

elbowloh

Yeah your BMX would have had horizontal drop outs, which you use for getting the chain tension

darrell1967

elbowloh said:

Yeah your BMX would have had horizontal drop outs, which you use for getting the chain tension

So vertical drop-outs can’t do that then? Hence the chain tensioner.

imposter2.0

Chain line and chain tension (or slack) are going to be the biggest issues. All very well saying 'put the chain on the 6th sprocket' - but unless the chain line is straight, it's not going to want to stay there. You can get single speed freehub spacer kits which will help you achieve a straight line, by replacing the cassette with a single sprocket and spacers.

MattFalle

You can use a single sprocket and lots of those plastic spacers from cassettes if you can't get hold of one of those those kits as above.

darrell1967

Thanks guys. I think I understand it all now.