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PostPosted: Thu Jul 09, 2020 11:38 pm 
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Joined: Sat Apr 02, 2011 11:16 am
Posts: 967
Location: Camden, London
so the Mrs has been using a 1997 Hahanna built into single speed on the short commute to work, and as anticipated she's finding it easier now and wants a higher gear. The learn to spin faster conversation has been had.

The current set up on wheel is here (same wheel and cog but different bike with a tensioner).

Image

I know ideally the ss cog should have a nice broad base to spread the load but the current cog is normal (3/32) thickness. My plan is to pinch a smaller cog out of a 7 speed which is same width as a trial to find the appropriate size and then splash out on a better cog of that size. The issue is the risk that the cog digs into the freehub. Is this real or just a myth. She's not an olympic sprinter so I'm thinking not an issue in the short term but just wondering if anyone has seen this in reality. The hub is a Shimano Alivio FH-MC18 (1999 ish). Current cog is 15, so next 14 and then 12 (assuming my other spacers will allow). Or move up from 36 to 46 chainring and 18 tooth cog from same cassette, you get the idea, the issue is not the gearing but not messing up freehub.

All thoughts gratefully received


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PostPosted: Fri Jul 10, 2020 12:20 am 
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Joined: Sat Apr 18, 2020 6:24 pm
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Non-SS specific cogs digging in is real, but if you're just testing out different cog sizes and letting her commute with it a few times then it's probably no big deal. I personally only ride SS specific cogs, but there's a lot of people that don't bother with that.


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PostPosted: Fri Jul 10, 2020 7:39 am 
Old School Grand Master

Joined: Mon Feb 11, 2008 9:42 am
Posts: 3614
A steel freehub, with correctly torqued lock ring and decent spacers (aluminium or steel and of the correct length) shouldn't have any issues.

You'll come unstuck if the lockring tightens against the end of the freehub, instead of the spacers, or if you don't do it up properly.


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PostPosted: Fri Jul 10, 2020 8:20 am 
Old School Grand Master

Joined: Tue Oct 09, 2007 1:55 pm
Posts: 10232
Location: New Forest, UK
No problem at all with steel freehub bodies (as yours is). Fancy hubs with alloy bodies will suffer digging-in and a singlespeed sprocket with wide base would be more advisable.


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 Post subject: Re:
PostPosted: Fri Jul 10, 2020 8:30 am 
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Joined: Sat Apr 02, 2011 11:16 am
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Location: Camden, London
thanks guys, so issue is real but probably less so in this instance if I do things properly. Yes, long term once settled on a ratio the plan is for one with a wde base, not least as not losing a cassette for sake of one cog.


So where is that torque wrench - I do have one from when playing with old cars, but I have to admit not used it on a bike, I've always relied upon "feel" ie tight but not over tight or stripping threads tight, and regular servicing and checking. Technically it's not been used in a while and should be recalibrated but that is another can of worms.


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 Post subject: Re:
PostPosted: Fri Jul 10, 2020 8:53 am 
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Joined: Tue Aug 21, 2018 3:43 pm
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Location: Cambridgeshire - flatlands (the horror, the horror)
we use a few single speed kits on the jump bikes and they don't exactly have an easy life, so we have some experience. Obviously there's little honking up long hills, but a lot a short burst intense pedalling (in my case mainly due to panic). Digging in is a problem on the soft alloy Hope free hub bodies. But then that's the wrong application of that free hub since Hope also do a stainless steel free hub which is tough enough to resist that. So it's the stainless steel ones which we run, despite the big increase in weight. And we have found that a shimano OEM ss cog is about the toughest one out there, which is good. The DMR and Gusset ones just aren't as good. DMR appear better kits than Gusset, in our view. Getting the spacers bang on for chain line and compressing enough when fitting the lockring (as mentioned in an earlier post) is vital. We still torque by hand for this, since experienced 'feel' still seems to trump a torque wrench in some contexts, this being one.


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 Post subject: Re:
PostPosted: Fri Jul 10, 2020 9:38 am 
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Joined: Sat Apr 02, 2011 11:16 am
Posts: 967
Location: Camden, London
Interesting feedback on the different cogs as I was probably just going to grab a gusset one off ebay.

We are in Camden, and she heads south so not having to get up Hampstead Hill. There is a slight rise on her way home (Euston incline), which was significant enough for the railways back in the day when they were first built and had quite an impact on local features/architecture but not really of the type you describe. For me the gearing was such that you spin like mad on the flat and have a sensible gears for the hills, but then I first started with a fixed gear in Cambridge and I don't really remember any ? :lol:


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 Post subject: Re: Re:
PostPosted: Fri Jul 10, 2020 10:04 am 
King of the Skip Monkeys
King of the Skip Monkeys

Joined: Wed Nov 07, 2007 4:34 pm
Posts: 32421
daugs wrote:
but then I first started with a fixed gear in Cambridge and I don't really remember any ? :lol:


Mill Road was rumoured to have an incline but it turned out to be a student prank


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 Post subject: Re:
PostPosted: Fri Jul 10, 2020 10:12 am 
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Joined: Tue Aug 21, 2018 3:43 pm
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Location: Cambridgeshire - flatlands (the horror, the horror)
...ah....the Mill Road bridge...bit like Bill Bryson on Nebraska...stand on a telephone directory and you can see for an additional twenty miles.


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 Post subject: Re: Re:
PostPosted: Sat Jul 11, 2020 5:29 am 
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Joined: Sat Apr 18, 2020 6:24 pm
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daugs wrote:
thanks guys, so issue is real but probably less so in this instance if I do things properly. Yes, long term once settled on a ratio the plan is for one with a wde base, not least as not losing a cassette for sake of one cog.


So where is that torque wrench - I do have one from when playing with old cars, but I have to admit not used it on a bike, I've always relied upon "feel" ie tight but not over tight or stripping threads tight, and regular servicing and checking. Technically it's not been used in a while and should be recalibrated but that is another can of worms.


I personally use torque wrenches for a lot, but I've recently moved away from using torque wrench on cassette lock rings. When I used to use my torque wrench set to 40nm it always became a hell to remove. My latest build has been set up for ss as usual but this time I haven't done the lock ring nearly as tight (I think) and we'll see if I end up trashing the whole freehub. :lol:


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