Stop me before I do something really stupid

Hi guys
just beginning my first fixed project, got an old mountain bike, with suitable dropouts. just like to run some things by you as i am not very familar with doing this kind of thing.
My bike has a 130mm spacing between the dropouts, was thinking of getting a disc brake hub with a bolt on cog from london fixie bike shop, this is mainly because seems easy to set up, and easy to swap cog sizes. if i buy one for a 135mm spacing will i have any problems, i presume just few mm of axle stick out to the side?

i am worried about my chainline, read a few articles, sheldon etc... seems very important. if i run a single chainring cog, where will that sit compared to my three cogs at the moment, i presume same as the outer larger cog, which i measure chainline at about 55mm, seems big??? most websites etc talk about chainlines in the low 40s. but as long it matches the rear cog doesnt really matter, does it??

any help appreciated before i splash the cash on something really silly..

Seb

Hi guys
just beginning my first fixed project, got an old mountain bike, with suitable dropouts. just like to run some things by you as i am not very familar with doing this kind of thing.
My bike has a 130mm spacing between the dropouts, was thinking of getting a disc brake hub with a bolt on cog from london fixie bike shop, this is mainly because seems easy to set up, and easy to swap cog sizes. if i buy one for a 135mm spacing will i have any problems, i presume just few mm of axle stick out to the side?

Contact/email london fixie bike.

i am worried about my chainline, read a few articles, sheldon etc... seems very important. if i run a single chainring cog, where will that sit compared to my three cogs at the moment, i presume same as the outer larger cog, which i measure chainline at about 55mm, seems big??? most websites etc talk about chainlines in the low 40s. but as long it matches the rear cog doesnt really matter, does it??

any help appreciated before i splash the cash on something really silly..

Seb

I am not sure any of your questions are formed clearly enough for me to offer any advice ! :( Sorry.

Youd be shoving a 135mm hub into a 130mm gap = bad idea. unless its a steel frme which might be alright. I'd contact LFB. I believe they space their hubs out to 135mm so can remove spacers back to 130mm??

On triples I think you get a 40-something chainline on the middle ring only, see Sheldon for the details. Pretty sure thats how Shimano do it. Better to get a cheapo RPM set for £25

135mm is standard spacing for tha back end of mtb's.

Its most probably likely your frame is just a little bent, try and put a 135 wheel in.

It will almost defeinetely go in just fine, but in the case that it doesnt, you can either try harder! or play with different sizes of washer/locknuts on your axles to ge tthe right size. If you are going with a solid axle, there is LOTS of room for adjustability.

My bike has a 130mm spacing between the dropouts, was thinking of getting a disc brake hub with a bolt on cog from london fixie bike shop, this is mainly because seems easy to set up, and easy to swap cog sizes. if i buy one for a 135mm spacing will i have any problems, i presume just few mm of axle stick out to the side?

I have 130mm rear spacing on my Raleigh, but for some reason measured it as 135mm when I was buying my wheel. As a result, I'm running a 135mm hub on the rear, but it hasn't caused me any huge problems. It does affect the chainline and I do notice more noise than on friends' bikes who have 130mm hubs, but I wouldn't lose any sleep over it. It'll be a bit of a tight fit, but you won't need to 'cold set' (i.e. bend) the frame to get it in - just wiggle it around a bit. As has been said - only do this on a steel frame, or you may be finding out first hand what the words 'catastrophic' and 'failure' mean.

If your rear spacing is 130mm though, and you can get a 130mm hub, then you should get a 130mm hub. I can't see the benefit in getting a disc brake hub on the rear over a standard track hub/fixed hub, but each to their own and everything... I got my wheel from On-One for about £70 IIRC and it's double fixed - just as easy to swap as undoing your locknuts, unbolting a cog and bolting another one on.

Now the Mercian I've just bought has 115mm rear dropouts - I'm thinking it's not the best idea to try and force a 135mm in there...

Dropout spacing, axle lengths and hub/cog spacing are not the same things!

Think about it like this: imagine a line running along the centre of your bike from the BB to the centre of the rear hub.
When people talk about a 42 or 46mm chainline what they really mean is that from this centreline to the cog is 42 or 46mm.
The axle spacing is the width of the rear hub plus all the spacers and should more or less match your frame. You can fit a 135mm hub into a 130mm steel frame and a 120mm hub will fit a 126 steel frame, but a 135mm hub into a 120mm spaced frame is a stretch too far, as is a 120mm hub into a 135mm (MTB) frame! You are safe enough with steel frames, but alloy frames might develop a crack if stressed like this.

Most hubs have one chainline regardless of the axle spacing offered. So for example a 42mm chainline hub might be available with 120, 130 and 135mm axle spacing. It will be the same forged hub body and the cog will sit in the same place. The difference is the thickness of the spacers added to the axle on each side of the hub body. so a 120mm hub might have 10mm of spacers either side and a 130mm hub would have 15mm.

Axles tend to be sized to match the longest spacing on cheap hubs, so a 120mm hub might have the same axle as the 135mm hub, the difference being that on the 120mm hub you end up with a bit more bare axle sticking out of the tracknuts when they are tightened down.
The exceptions would be quality hubs where the axle will match the hub spacing and Phil and Goldtec type hubs which use allen key fastenings and the axles are sized for the hub spacing, since the axles do not stick out beyond the frame, the bolts screw into the axles instead.

So for your first question:
130mm spacing on the frame. If you buy the 135mm hub, you'll need, ideally to remove a spacer from either side of the hub to reduce the hubs width. OR you can fit it as it is and it will spring the frame out 2.5mm either side. This should be fine. It will not affect the chainline at all.

The chainline is tricky. Ask in the shop, they should know roughly where that cog lines up to on an MTB triple. My guess is that it will line up with the middle chainring.

The middle position of the 3 chainrings usually gives a suitable chainline.
Using the outer position looks better, but works worse.
Good luck!

I've done what you're about to do with an on one single speed disk hub and a bolt on cog. Outer ring ended up working for me on the chainline front but you may have to change you b.b to fiddle it a bit I was lucky.

Also if you are running the bike on road consider putting 700c wheels in it for extra b.b height. You can use a coomponents Pauls v brake on the front with 700c wheel and use the same canti studs. Enjoy.

I been running a fixed mountain bike frame for some months too.
Mines a 135mm spaced rear mountain bike hub with two 1mm washers between the disk mounts on the hub and the ISO mounted cog and a 2mm spacer on the drive side of the BB (This is to allow clearance of the shimano cog which is mounted on the hope hub).

The saint Cranks naturally have a 50mm chainline which becomes 52 with the spacer on the BB shell.
Lots of measuring and trying differnet things has allowed me to get the chainline perfect.

Note that if you use a front hub (100mm) spaced out to 130, rather than a rear hub as I do, that your chainline is likely to be around 47mm when you add the 15mm spacer to each side of the axle.

I was mainly thinking of the london fixie shops bolt on gear solution as it seemed fairly simple, and not too pricey. remember i am just looking to commute and city ride on this bike. i looked for 130mm spaced fixed or flip flop hubs but dont seem to be many out there, and the ones i did find seemed pretty expensive and aimed at track cycling. if anyone knows a source of cheaper 130mm hubs wopuld love to know.
seems that there isnt a one best solution, but different ways to convert my bike.
so can i ask with 130mm spaced dropouts how would you do it, for cheapness and simplicity.
thanks

I expect your rear spacing is 135 not 130 if it's a mtb.

will check again, but i am quite sure its 130mm, it is an older mountain bike, not sure if this makes a difference.

IF it is 130 still use a 135 mbt hub the frame will spread easy.

tommy are you running your mountain bike brakeless?

tommy are you running your mountain bike brakeless?

Only for polo, because I enjoy bar spinzzzzzz too much when I am not playing.

After a bit of reading here, I was fairly confident that I could put a 120mm hub into a 126mm dropout, with spacers but I just got back from the bike shop who said that I shouldn't and it would be better to replace it.
His argument was that the hub needed direct contact with the frame not through spacers. I am not sure if it was my mistranslation of Polish or if that is what he was saying.

I'm not sure what to do now - It seems like I could just tighten the nuts and it would squeeze the frame together - it is only 3mm each side after all. Is that safe or should I put in some spacers? If so do 'spacers' mean any washer I can find or is there a special requirement?
Thanks

we've all done it*

dont worry about the spacers. i would however worry about the space between your post and the one before it... that's an epic ressurection!

check out the mechanics or bikes and bits forums for help.

*me too.

you should be able to just tighten up the nuts as long as your frame is steel.

or as long as the spacers are 3mm each side, no?

yep, think so!
as long as your axle is long enough then go for it, it's only 3mm on each side at the end of the day...

true dat :)

Ive done it on a few bikes without any problems. you can get 2mm spacers and 1 mm spacers so they add up to 3 mm. just make sure your chain line is good. i wonder what the biggest post resurrection is?
make sure your axle is long enough, which it should be.
A bike shop that was trying to sell you a new wheel instead of £2 worth of spacers you should probably go somewhere else.

Yeah I couldn't find a more recent post that was more or less on topic.
So I'm not going to bother with the spacers - I can even close the gap just tightening with my fingers so I can't imagine it is such a huge strain on the dropout.

I am stuck for bike shops here. As I have said before - they all want to sell you a new frame(MTB of course) or something else rather than fix your problem.
This shop is the first I actually found that had a mechanic who wasn't a grumpy arse and was actually interested in helping me build a bike. This is the first dodgy advice I have heard from him though.
Thanks guys