Would a early 90s Diamondback MTB frame be okay to turn into a fixie?

Femto

New Member
So, I've had this old Diamondback rigid mtb in my garage for donkeys and seeing as I've been having thoughts about trying fixed out, I'm wondering if this bike would be a suitable candidate for conversion?

The rear dropouts seem to be sort of diagonal, favouring the horizontal but they're definitely not vertical.
The frame's made of Cro-Moly I think and seems reasonably light.
Not sure I'm overjoyed about the canti brakes that are on there but I'm not massively bothered either.

Any thoughts, please?
 
Location
Edinburgh
Any frame that allows you to adjust the chain tension can be used to make a fixed wheel or single speed. Go for it, it may not look like the latest high street fashion accessory, but it will probably be fun to ride.
 

RedBike

New Member
Location
Beside the road
I'm loving riding my MTB fixed wheel.

In general I wouldn't recommend fixed wheel for MTBing, it makes anything technical 10x harder and ruins the descents. However, for my flatish singletrack trails to work I wouldn't want to ride anything else. It just makes them so much more fun!
 
OP
Femto

Femto

New Member
Touche, without a paint job, it'll never look like a fashion accessory but style isn't what I'm going for, fun is. :tongue:

RedBike, I don't go off road if at all possible so there's no problem there. I'm contemplating putting more road-oriented tyres on the rims. Probably a sort of hybrid type of tyre rather than the nobblies that it's currently wearing. I suppose I'll have to change the hub as well. Maybe new wheels would be easier? I imagine replacing a hub is a bit spokey-dokey and not something to be done solo having never done it before!

I commute to work on my road bike but I could try it on a fixed. The route has a couple of hills but nothing that requires low gearing. I think the steepest is about 10%.

Apart from anything else, I think I'd like to try the conversion just to see if I can. :-)
 

tyred

Legendary Member
Location
Ireland
You shouldn't have to change the hub if it's of the thread on freewheel type. If it's got 5 or 6 sprockets, it's definitely a screw on type, 7 could be either. You will need a lockring from an old bottom bracket to make sure your sprocket stays on and you may have to respace and redish the wheel but it's not that difficult.
 

RedBike

New Member
Location
Beside the road
If you just screw a fixed sprocket onto a hub it probably won't line up correctly. Therefore you will either need to re-dish the wheel or fit a converter. (Search ebay for fixed hub)
 

ColinJ

Puzzle game developer
Femto said:
So, I've had this old Diamondback rigid mtb in my garage for donkeys and seeing as I've been having thoughts about trying fixed out, I'm wondering if this bike would be a suitable candidate for conversion?

The rear dropouts seem to be sort of diagonal, favouring the horizontal but they're definitely not vertical.
The frame's made of Cro-Moly I think and seems reasonably light.
Not sure I'm overjoyed about the canti brakes that are on there but I'm not massively bothered either.

Any thoughts, please?
Touche said:
Any frame that allows you to adjust the chain tension can be used to make a fixed wheel or single speed. Go for it, it may not look like the latest high street fashion accessory, but it will probably be fun to ride.
I made a singlespeed road bike out of an old geared Basso which had semi-horizontal dropouts and it works just fine.

semi-horizontal_dropouts.jpg


ss4.jpg
 
OP
Femto

Femto

New Member
Ooh, pretty bike Colin! What gear inches are you running with?

Also, what've you used a spacers on there? Brass? Or is that a cover of some description that you've slid over?

Those dropouts seem very similar in angle to the ones on the old diamondback. I think I'll give it a go now that I've seen a success with the same type of dropouts.

I may have to buy some drop or bullhorn bars as I went out on my old hybrid the other weekend and I wished I was on my road bike before very long.

Tyred: I think it's a 7 speed cassette.

RedBike: I was wondering if there'd be some tweaking to be done in order for things to line up. Highly important for fixed, I'm told.
I wouldn't want to find out what happens when the chain jumps off and jams the rear wheel up at speed. Sounds knee-shatteringly bad.
 

ColinJ

Puzzle game developer
Femto said:
Ooh, pretty bike Colin! What gear inches are you running with?

Also, what've you used a spacers on there? Brass? Or is that a cover of some description that you've slid over?
It's 39/15 so that's, er, 70 inches?

The spacers are the plastic ones from two old cassettes. I worried that they might crack but I've done several hundred miles on the bike now and all is well.

The dropouts have little bolts through them at the back so I can adjust how far back the axle sits in the dropout as the chain wears. I haven't had to do it yet because the chain wear is minimal.

I've got the frame/forks and wheels on semi-permanent loan from a mate who has emigrated. I had most of the other bits in my junk box so it only cost me £25 to put together! :sad:
 
OP
Femto

Femto

New Member
Well 39/15 was what I was thinking too. I dare say some of the hills around Keighley might be a little bit stiff at first but I've got my road bike for those. :wacko:
I take it you have a multi-speed bike as well? Hebden bridge, or rather its surroundings aren't well known for flatness! Shame about your pal's punctures the other day (just been on your website). :sad:
 

RedBike

New Member
Location
Beside the road
Tyred: I think it's a 7 speed cassette.
In that case there is no easy way to use your existing wheel as a fixie. If it's a shimano hub you can use the Surley Fixxer but its probably cheaper just to buy a new wheel or stick to running the bike single speed.

I'm not sure of the dropout spacing with your existing frame but if it's 135 the easy/cheap way to do convert it is to buy a disc braked (6-bolt) wheel that has a rim braking surface. Then you can bolt the fixed sprocket to where the disc rotor would normally go and use the cantilever brakes as normal.

My fixies chainline doesn't line up perfectly. Provided the chain is reasonably tight theres little chance of the chain jumping off. I have had my chain fall off a few times (because its been too slack). Luckly its always just fallen to the side of the sprocket and the bike has 'free wheeled' to a stop with no drama.

You will be amazed at the sort of hills you can climb fixed/SS. If you can climb the hill using 39x15 on a geared bike then the fixie will just fly up it with that ratio. Don't forget colinJ is using 700c wheels whereas I presume you will be on 26" wheels. This will make a big difference to the gear ratio.

Most shop bought fixies tend to come with either 48x18 or 42x16.
 

ColinJ

Puzzle game developer
Femto said:
Well 39/15 was what I was thinking too. I dare say some of the hills around Keighley might be a little bit stiff at first but I've got my road bike for those. :sad:
The s/s bike is at my sister's house in Coventry where any hills are much smaller. I certainly wouldn't fancy doing many Yorkshire hills on it!

Femto said:
I take it you have a multi-speed bike as well? Hebden bridge, or rather its surroundings aren't well known for flatness!
Too right - I have a triple chainset and big sprockets! :smile: (52/39/30 + 14-28)

Femto said:
Shame about your pal's punctures the other day (just been on your website). :biggrin:
Yeah, it did spoil the ride. I realised a few days later that we could perhaps have sacrificed one of the dead inner tubes and used it as rim tape. It might have worked?

We went out on Sunday and did a different hilly ride instead. I'll be writing that up for my blog in an hour or two.

Calum had put new rim tape on for that ride and had no further problems, unlike me - my right leg packed up again when I refused to get off and walk up a very steep hill. I'm hoping that it is something trivial that I'll recover from like a slight muscle tear. :sad:

RedBike said:
My fixies chainline doesn't line up perfectly.
My first attempt with the s/s wasn't quite right so I shifted the sprocket over by one spacer and it is now pretty much perfect.

RedBike said:
You will be amazed at the sort of hills you can climb fixed/SS. If you can climb the hill using 39x15 on a geared bike then the fixie will just fly up it with that ratio.
I don't think that s/s is great for climbing unless you happen to be in the gear that you would use on a geared bike (or maybe one gear higher since the transmission is that much more efficient and the bike is lighter). I find it hard to get the pedals through the two dead-spots in the pedal stroke.

I'm overweight and haven't got enough miles in this year but hills up to 5% are fine on 39/15. 6% - 8% feel hard but doable. Anything steeper than that and I really struggle.

RedBike said:
Don't forget colinJ is using 700c wheels whereas I presume you will be on 26" wheels. This will make a big difference to the gear ratio.
True.
 

RedBike

New Member
Location
Beside the road
I don't think that s/s is great for climbing unless you happen to be in the gear that you would use on a geared bike (or maybe one gear higher since the transmission is that much more efficient and the bike is lighter). I find it hard to get the pedals through the two dead-spots in the pedal stroke.

I'm overweight and haven't got enough miles in this year but hills up to 5% are fine on 39/15. 6% - 8% feel hard but doable. Anything steeper than that and I really struggle.
I think we all struggle on the very steep climbs.

It's odd you should post about the dead spots. The thing I like most about the fixie is you don't notice the pedal deadspots. When you switch back to gears after riding fixed for a while the first thing you notice is the cranks suddenly feel like they're going through a sticky patch around the 7/1oclock position.

There are hills on my commute that I struggle to get up on my geared bike using 39x25. If I was to change gear to 39x15 i'm almost certain I wouldn't get up the hill.
Yet i've never failed to get the fixie up these climbs yet (using approximately this gear).

The fixie just seems to slowly lumber up the climbs. You can get away with a stupidly low cadence because the rear wheel seems to act as a flywheel and pulls the pedals through the dead spots.
 

ColinJ

Puzzle game developer
RedBike said:
It's odd you should post about the dead spots. The thing I like most about the fixie is you don't notice the pedal deadspots. When you switch back to gears after riding fixed for a while the first thing you notice is the cranks suddenly feel like they're going through a sticky patch around the 7/1oclock position.
...
The fixie just seems to slowly lumber up the climbs. You can get away with a stupidly low cadence because the rear wheel seems to act as a flywheel and pulls the pedals through the dead spots.
I rode behind longers (who was on his fixed gear bike) up a couple of steep hills and watched him carefully. I'm convinced that the 'flywheel effect' is what makes it possible.

On my s/s bike I can feel the bike slow down and speed up at different points in the pedal stroke. The problem is that I pretty much come to a standstill at the deadspots and then can't get moving again.

I think the deadspot is really 11/5 o'clock but I suppose it depends which side you are looking from. 11/5 o'clock from the drive side of the bike. One you get the crank beyong 12 o'c you can start to get your weight behind it again.
 

battered

Guru
You can certainly use an old inner tube as rim tape. It's not a permanent fix but it's certainly a get you home, by the time the spokes have chewed through the old tube you'll probably be back home drinking tea and in a position to fix it propely.
 
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