Woke up this morning and thought....

[nickfrog]

I only need 1 ring. I never use the big ring and only occasionnaly the small one. I run a full M950 8-speed group with 24/36/46 and 12-32.
So I am thinking of going 9-speed with a 28 ring and a 11-34 cassette.

Benefits are sinplicity and saving maybe 350g.

Questions:

1 - How do I convert my M950 crank into a single ring. Is it easy to source and fit a compatible spider and ring ? Any recommendations ?

2 - Will the gaps between gears be too great ? I have done some calculations and it does not look as shockingly spaced out as I thought on paper but in the real world ?

3 - Will the chain be prone to falling off the ring ?

4 - Any issues that I have naively ignored ?

Cheers!!

 

[Harryburgundy]

28 up front is a bit small unless of course your terrain dictates this...36/38 with 11/32 would be better maybe.
I use a Pauls chain keeper but plenty of alternatives

 

[barry2017]

Just for a test, why don't you fix your front mech permanently onto the front ring, to see if you like it?

 

[nickfrog]

28 up front is a bit small unless of course your terrain dictates this

It's more my level of fitness dictating it...

The problem is that I live on the South Downs where the climbs are short, rare BUT steep and at 41, I still want an easy option equivalent to my easiest gear even at the detriment of bigger gears.

28t ring with 34t gives me 1.7m which compares well with my current set up of 1.6m (24t ring with 32t) while at the other end, 28t ring with 11 gives me 5.3m, which is not too far off my current 12t with 34t ring (5.9m).

 

[nickfrog]

Just for a test, why don't you fix your front mech permanently onto the front ring, to see if you like it?

Possibly but I know I won't like it as it's 34 rather than the projected future 28t.

 

[Neil G]

34 would still give you a good bottom gear. I'm running 35 and 11-32 up back and haven't missed the granny ring despite some steep climbs

 

[kaiser]

Have you had a mess about with sheldons gear calculator?

 

[kaiser]

BTW is the 950 the same spider type arrangement as the 952? If so look for homebrewedcomponents, he has a 28 tooth chainwheel.

http://www.homebrewedcomponents.com/store.php

 

[xerxes]

There is also the issue of chain alignment. If you just have the centre chainring of a triple chainset at the front, the chain has to curve a lot to reach the inner and outer-most sprockets of the rear cassette, which places extra stress and wear on the chain when used like this.

In general a triple chainset set-up, whether it's 18,21,24 or 27 speed, is designed so that the inner chainring is used with the inner most sprockets of the cassette, the middle chainring with the centre cassette sprockets and the outer chainring with the outer cassette sprockets. This diagram and comparison with a 14speed hub gear sort of explains it: http://www.rohloff.de/en/products/speedhub/gear_range_comparison/index.html

 

[nickfrog]

34 would still give you a good bottom gear. I'm running 35 and 11-32 up back and haven't missed the granny ring despite some steep climbs

34 is my middle ring atm and while I would go from 32 to 34 max at the back, there will be a massive difference in bottom gear, which I won't even contemplate running.

34 x 34 would give me 2.1 meters against my current bottom gear of 24x32 that gives me 1.6 meters, that's too much of a gap I fear, but i could be wrong.