Mountain Biking Association of Dublin



Author Topic: Help needed with single speed conversion  (Read 151 times)

Mark Mc G

  • Club Members
  • Newbie
  • *
  • Posts: 15
  • Karma: +0/-0
Help needed with single speed conversion
« on: 28, January, 2020, 11:50:57 AM »
Hi all - I had a Populo Quest converted to a single speed. However the wee chain tensioner has given up the ghost. After about 12-15 months the spring seemed to go, however it sufficiently held the chain in place the vast majority of the time. Itís now 18 months and itís barely hanging together - the chain skips 4-5 times every full pedal rotation which, needless to say, is tiresome when commuting.
[/size]Previous googling suggested that these tensioners are usually not great. So has anyone any experience or suggestions on what can be done? Are things like removing a link in the chain an option? Or are there better solutions out there?
[/size] I've tried to attach a photo but it keeps failing, so I've uploaded it online. https://imgur.com/a/NoY8Dbr
[/size]Cheers
[/size]Mark

saccades

  • Club Members
  • Full Member
  • *
  • Posts: 239
  • Karma: +6/-0
Re: Help needed with single speed conversion
« Reply #1 on: 30, January, 2020, 09:45:08 AM »
Just to get a bit more info, did you use a cheap conversion kit?


When you say it skips, the front or the back (back I presume)?


Obviously simple things like correct spacing, chain line matching and decent SS specific cogs not being right accelerates the wear.


You could try to play with different teeth ratios front and rear (try to get a more similar size cogs), or a half link to tweak the tension in the chain so that you don't need the tensioner.



But when it gets down to it, the spring tensioners are a bit crap - it's why I've only used track ends or an ebb for SS.


I did consider this style of tensioner that gets decent reviews for MTB SS.[size=78%]https://www.bikemonger.co.uk/gusset-bachelor-ss-tensioner-28-p.asp[/size]


A bit more expensive but if charlie rates it, it must be decent.
[/size]

Mark Mc G

  • Club Members
  • Newbie
  • *
  • Posts: 15
  • Karma: +0/-0
Re: Help needed with single speed conversion
« Reply #2 on: 30, January, 2020, 11:52:26 AM »
I donít know about the quality of the conversion kit - when I was buying the bike I asked if there were any single speeds with disc brakes, and they said no but could put something together. Iím pretty sure itís the back thatís skipping (hard to check while cycling).


I was kind of surprised when it came with a tensioner only the first place. I would have assumed that there would be a combination of front and rear gears that wouldnít need it


Whatís a Ďtrack endí or an Ďebbí?

saccades

  • Club Members
  • Full Member
  • *
  • Posts: 239
  • Karma: +6/-0
Re: Help needed with single speed conversion
« Reply #3 on: 30, January, 2020, 03:26:45 PM »
That combo is called the magic ratio - it's called that because it's so rare. Your hoping for two things to come together for it to work, absolute chainstay length and dropout positioning. If those two are not right your banjaxed. You'll only find out after trying loads of different cog combos (which is expensive, defeating half the point of single speed).


Ebb = eccentric bottom bracket, the BB is offset from the middle. So as you rotate the BB in the shell of the frame it moves forwards or backwards, effectively taking up the slack. It's a really neat solution but can creak/slip at times.


Trackends = your dropout (the bit that the axel of the wheel goes into) has the open bit facing the ground, that's called a vertical dropout, it ensures that the tension of the cable and the derailleur stay consistent compared to the cassette to give you consistent shifting.


On a track bike there are no gears (they are SS) so the face of the drop out is generally facing backwards (aka track ends or horizontal ends). It makes taking up the slack very easy as you just pull the wheel further away from the BB in the track end then tighten the bolts.




 This is why people buy track bikes to make an SS as the track ends make it easy, it's also daft as track bikes don't have brake mounts - and it's pretty much impossible to brake rapidly using your thigh muscles.




 


 

Copyright © Mountain Biking Association of Dublin