easiest way to fit a 5 bolt chain ring to a 4 bolt crank?

[whereswally606]

So I have recently been re-inspired by barino GMBH in switzerland to upgrade my scott ransom a little.

one of the things he/she (not sure which) has managed to do is fit a 55 tooth chainring made by sram. He also has 4 bolt cranks. I looked at the pictures and im guessing they made something custom. The sram 55t tooth was very expensive and ill be happy with 52t cause i can just about get one of those cheap enough.

still have the problem of converting from my 4 bolt octalink cranks to a 5 bolt road 52t chainring.

method 1. buy a 4 bolt chainring with a solid section like the DMR saturn

and drill my own 5 bolt holes in it. This is £24 quid before i've even bought my 52t chain ring

method 2. buy a very cheap on offer BMX solid chainring circa £5, drill 4 bolt holes and 5 bolt holes. and a big central hole and risk it turning out wonky.

method 3. ask Endless sphere if they knew a solution. please bear in mind I already checked google for adapter/convertors and all i seem to find is ones for car wheels. My search fu my be way off though.

reason for all of this is pedaling should not feel like a waste of time on an ebike unless you are pushing some serious watts through your motor.

 

[amberwolf]

You could also make your own chainring; there's a few websites with calculators and template-makers out there. You just have to be able to drill holes centered on the template markings, and file the edges after.

 

[dogman dan]

In my world, easy would be going to ebay and finding the crank with the right bolt pattern for the chainring you plan on using. Bearing in mind though, that road bike cranks often hit the frame on a MTB.

It can be very difficult to source exactly what you need. At one point, I got very lucky and found a 56 tooth chainring on ebay that was made to fit a mtb cranks 5 hole spacing. Even so, it can be used on some frames, and not on others. Thinking I'd get a wider bb, I found the mtb's had the wide one already.

 

[Drunkskunk]

method 2. buy a very cheap on offer BMX solid chainring circa £5, drill 4 bolt holes and 5 bolt holes. and a big central hole and risk it turning out wonky.

That would be my second choice.

My first choice would be to replace the crank arm with a 5 bolt style. You can find bikes cheap at garage sales. Buy the whole bike for $20 and use just the crank arms. Then stick your old 4 bolt crank arms on it and sell it yourself for $20. Or give it to charity and claim a $200 tax write off.

 

[whereswally606]

thanks for the suggestions so far.

You could also make your own chainring; there's a few websites with calculators and template-makers out there. You just have to be able to drill holes centered on the template markings, and file the edges after.

Sorry AW, I really don't want to do to the trouble of making a complete custom chain ring though sounds fun if i had the time or the tools

Bearing in mind though, that road bike cranks often hit the frame on a MTB.

I did think that road bike cranks would be closer in and so hit the chainstay, plus i have octalink BB and they seem expensive to buy as 5 bolt road cranks for.

I got very lucky and found a 56 tooth chainring on ebay that was made to fit a mtb cranks 5 hole spacing.

most mine will take according to barino in switzerland is the 55t sram kettenblatter (£90) but yeah I am looking on ebay too.

My first choice would be to replace the crank arm with a 5 bolt style. You can find bikes cheap at garage sales. Buy the whole bike for $20 and use just the crank arms. Then stick your old 4 bolt crank arms on it and sell it yourself for $20. Or give it to charity and claim a $200 tax write off.

I don't want to put cheaper cranks on the ones I've got are good. Also garage sales are maybe not so common in the UK as the US.

I think i will go for buying the DMR saturn or something like it. and a 52t chain ring. I'm going to make an exact template for the 5 bolt pattern to drill those. It will probably set me back about £50 all in. but its the most likely to succeed.

Thanks for the advices, any new ideas? I'm still open to suggestions.

 

[N!co]

Another option: http://www.rennendesigngroup.com/store.html

 

[whereswally606]

That looks like no bother at all there N!co thanks.

I can have a 52t ring for a 4 bolt cranks for $50 delivered, amazing.

What i don't understand are the decimal gear increments? how do you get half a tooth?

 

[MAGICPIE3FOCUSPOWER]

Another option: http://www.rennendesigngroup.com/store.html

What does the increment mean?

Ooops I see the question has been asked

 

[whereswally606]

increment is an increase but thats not what im asking, i was asking how do you have a chain ring with less than whole teeth counts?

 

[MAGICPIE3FOCUSPOWER]

No I mean what does the 0.2T, 0.3T, 0.4T etc. etc. mean?

 

[N!co]

I have never ordered from them, but i found it in my search for a larger chainring on my MTB.

http://www.rennendesigngroup.com/Decimal.html

I don't know for sure, but i think they increase or decrease the spacing between the teeth a little.

 

[MAGICPIE3FOCUSPOWER]

Thanks!

It's quite simple.
It's just adding a teeth by 0.XT instead of 1T or more.

 

[MAGICPIE3FOCUSPOWER]

Don't buy from them!

I have ordered one, after 25 days still nothing!
When I ask for tracking number, there is no response!

 

[John Bozi]

Don't buy from them!

I have ordered one, after 25 days still nothing!
When I ask for tracking number, there is no response!

Did you get it yet? I am after the same thing...

 

[MAGICPIE3FOCUSPOWER]

Yes finally I have received it, but after more then 30 days

Now I have ordered second one one month has been passed, still nothing
So this is my learning lesson....... :lol:

 

[John Bozi]

Yes finally I have received it, but after more then 30 days

Now I have ordered second one one month has been passed, still nothing
So this is my learning lesson....... :lol:

what increments did you chose? (0.t etc) and why? as I don't understand them.
What's the diameter of the 52t? I want to measure to see if she will fit against my swing arm.
What's the difference between the threaded and non threaded ones?

thanks mate.

 

[MAGICPIE3FOCUSPOWER]

At first order I have ordered 52.9T, it's just a 52T chanring, but the spacing between the tooth's are different then a normale 52T chainring. So the 52.9T acts like a 53T chainring...

Threaded chainring you only need the bolt to install the chainring.
There is already thread on the chainring, so only bolt is needed.

Non threaded it's just like your MTB bike chainring, you need bolts and nuts to install the chainring.