Converting old MTB to Single speed - what is needed/cost?

[mattrixdesign2]

Hi

I have an old Saracen Tuff Trax (87), I am going to use it for the winter commute, I have changed the front wheel as the old was loose and brake surface worn, put some narrow slicks on (1.5in). The bike is quite heavy and although the gears work and are functional I want to try and simplify things and shave off a few pounds.

I am trying to learn more about bikes in terms of how to fix/add/repair things myself with the help of the WWW. I have changed a full group set on road bike etc.

So if I want to go single speed what do I need to do - simple/cheap/effective option.

I will be buying a cheap rear wheel to match the front (MTB/Leisure wheel from Decathlon).

I presume I need a single sprocket for the rear, some sort of adapter for the free wheel, single chain ring up front (and new crank set?), do I need a new chain and some sort on tension thing?

Any good guides to refer me to, like how to get the correct chain length, alignment etc?

What about tooth count, for a short flat run, and maybe with some load lugging via panniers.

 

[Jussa]

First of all dig around on here you will find loads of info on SS, but to get you started here is my first SS and how i did it, firstly on a budget and then neatened it up with a proper kit,

Initially i had 2 x old rear cassettes which were really cream crackered and not worthy of fitment. I filed off the heads of the pins holding them together. Hey presto i was left with 10 x Plastic spacers and a selection of loose cogs. Using my Hub i was able to slide on the spacers and choose a suitable cog continue to pack out with spacers and screw on the retaining disc. * As frame geometries vary you can position the rear sprocket anywhere along the axis between the spacers. its trial and error sometimes but patience will provide great rewards. The selection of different sprockets will also mean you can try different ratio's.

Ok, hopefully the pictures will say a thousand words.

Getting chain tension is dependant on the length of the stay, size of front chain ring and rear cog. You can get a 1/2 link, but you will find that if you play around with ratio's you could be adding and removing links left right and centre. I could not get it to work without any form of tensioner so eventually invested in a DMR Single Speed kit which came with spacers and dedicated rear cog. can get these from ebay very cheap, think i paid £15 for mine second hand.

This made for a much neater set-up and provided us with a great riding experience Happy Days, some Schwalbe City Jet Tyres fitted and my lightweight ride was sorted.

Front crankset was just stripped of the two surplus rings and left with the middle ring, which for me worked well with the ratio and environment i was using it in which was basically around town as an urban commuter.

Hope this gives you food for thought,

Jussa

 

[mattrixdesign2]

Thanks!

The bike is currently old Shimano 7sp x 3, so if I was to get a new rear wheel this will be fine to fit in the rear of the bike and take a modern single speed kit?

Then I just need to understand tension and alignment, I will read up on it.

 

[Jussa]

Thanks!

The bike is currently old Shimano 7sp x 3, so if I was to get a new rear wheel this will be fine to fit in the rear of the bike and take a modern single speed kit?

Then I just need to understand tension and alignment, I will read up on it.

Cassette rear wheel will accommodate single speed, if its screw on freewheel then a screw on BMX style freewheel is what they use.

You have scope to move the position of the rear sprocket with spacers and rings and it will be visual thing as the geometry and alignment with front chainset differs from bike to bike especially as you are losing the front and rear mech which control the movement of chain. Tension will depend on sprocket size and front chainset size and chain length, trial and error will be the order of the day, but the tensioner will take the pain away and provide you with an adjustable method of tightening the chain until you get the ratios your happy with.

 

[mattrixdesign2]

thanks... now running in 1 x 6 (I think its 6 speed) thanks to my £20 Aldi tool kit, trying to work out what tooth count I need at the rear.

I use the bike for a commute (only 2miles) and to do some local shopping (2 paniers), so not sure, going to see which gear I am using most at the back.

The bloody chain rings are oval - presume that wont effect things?

 

[bm0p700f]

ovsl chaings make no difference I have tried and proper chain tyension was maintianed. You can do this without a tensioner.

Each tooth added/taken away front or rear add.takes away 1/$" from the totlas chain wrap. so start with the chain around your middle ring and any cog at the back and see how many 1/4" you are from joining the chain. that how many teeth need to be added or taken away from the front or rear or both to join the chain. 1/2 links this way are not normally needed.

Once you know a ratio that works then others can be determined.

For example for me 34:16T works soa 36:18T will also work but and extra 1" of chain will be needed.

 

[suburbanreuben]

Working out the ratios that work without a tensioner is a real pai in the arse! THe very common 16.75" chainstay will not accomodate any combination of ring and cog with a new chain; 17" will , as will 16 5/8". Measure your chainstay, centre-centre and play around with this: http://eehouse.org/fixin/formfmu.php

You should get a good idea of the ratios you can use. 32;16 is the benchmark ratio for general use offroad. If it's flat you could go higher...

 

[integerspin]

Surely nothing needed. Leave it in the gear of your choice, then don't
give in to the temptation to change gear.

 

[mattrixdesign2]

Surely nothing needed. Leave it in the gear of your choice, then don't
give in to the temptation to change gear.

I understand, but I am just messing about and learning along the way, already feels good to strip the bike of 2 chain rings/cable/outer and shifter, so I am doing the same for the rear.

I don't care if it looks right, or is the "right" thing to do, just by removing the chain rings, and crank arms (to get he smallest chain ring off) I have learnt a few things... at the end of it I sould be left will a simple bike for winter commute and messing about on, can jump on my geared road or MTB at any other time.

 

[Jussa]

Surely nothing needed. Leave it in the gear of your choice, then don't
give in to the temptation to change gear.

I understand, but I am just messing about and learning along the way, already feels good to strip the bike of 2 chain rings/cable/outer and shifter, so I am doing the same for the rear.

I don't care if it looks right, or is the "right" thing to do, just by removing the chain rings, and crank arms (to get he smallest chain ring off) I have learnt a few things... at the end of it I sould be left will a simple bike for winter commute and messing about on, can jump on my geared road or MTB at any other time.

dont worry you are doing exactly what i did, as you can see in the pics, i was left with a nice clean, lightweight bike an understanding of the Single Speed concept whilst having a lot of fun and learning all the way Stick to your guns