refurbing / modernising a rockrider 8.1 - PROJECT STARTED

danlightbulb

Hi all

I have a decathlon rockrider 8.1 from 2012 in 26" wheels. It was a decent bike back then for the budget end.

I never replaced any parts on it when i uses it but now I want to make it available to a friend to come with me and try out mountain biking.

it has 3x9 gearing. A 100mm recon spring fork. avid elixir 3 brakes.

The gears are well worn so need replacing anyway. Can i put a 1x system on it? If so, dont want to spend too much, what can I go for? It uses a shimano external bb, will everything be compatible with this?

Brakes should be straightforward. What about wheels and fork? It has a straight headtube. I guess ill be restricted at the back end but what about the front i terms of wheels?

Any advice appreciated.

danlightbulb

My other option would be to make a tourer out of it. Keep 3x9 fit drop handlebars and slimmer tyres. How would this work with an aluminium mtb frame and disc brakes?

The Rookie

Decide which you want to do!

Yes you can go 1x, you can go 1x9 (using an 11:34 as I did or a wide range 9 speed cassette from Sunrace) or 1x10 using a cassette chain and 10 speed flat bar road shifter with your current 9 speed mech.

Cranks, I'd suggest a decent used HT2 along with a narrow wide ring and a new BB.

Touring you can do as well.....

danlightbulb

Would 1x11 not fit?

I could probably keep 3x or go 2x as the 3x did me ok for years even on trails. Then it would be a bit more all purpose?

Whatever i do i want to replace both mech, cassette, shifters, front chainrings as they are worn out.

bonzo_banana

Looks a great bike for its day couldn't you just give the forks and bike a service and start using it again.

Wiggle were doing a 12-36T 9 speed cassette for £12.99 a week or so ago you could use that as the basis of a cheap 1x setup. I think Decathlon themselves are doing a 11-36T 9 speed cassette for £10.99 but its a lower quality brand.

I assume it wouldn't be too difficult to remove a chainring or two from your deore crankset and turn it into a 1x crankset.

Improvise a chain tensioner if you need to.

Looks like it could be a really nice introductory mountain bike with only a little bit of money spent.

https://bike-advisor.com/reviews/rockri ... -2013.html

Whatever you do with it, stick some photos on here of the finished build.

whyamihere

1x11, or even 1x12 if you use a Sunrace or Sram NX cassette (with Shimano style splines, not XD), are possible and will fit without problems. I think Rookie was probably suggesting cheaper options due to it being a relatively old, less expensive bike. If you like it though, there's no problem with putting the upgrades on.

If you want to change the fork, you'll need to know your steerer size (which you've already stated as 1 1/8" straight) and whether the front wheel is QR or bolt through. If there's nothing actually wrong with it though, I'd leave it - Recons weren't/aren't bad forks.

danlightbulb

If I was going to use it as a tourer id probably put a rigid fork on, but unsure what happens with disc brakes then? Also what happens with disc brakes if i fit a road style drop handlebar?

Its a tricky decision. I also wanted to do some events this year. I could turn this into a decent xc bike and keep my full suss for the trails. But i could equally do some road events if i turned it into a tourer.

The Rookie

danlightbulb wrote:

If I was going to use it as a tourer id probably put a rigid fork on, but unsure what happens with disc brakes then? Also what happens with disc brakes if i fit a road style drop handlebar?
.

You fit rigid forks with a disc brake mount, I've had discs on my commuter since 2009 (that was with a 2005 bike, so hardly new).

You get drop levers for hydraulic brakes or convert to cable pull calipers (Road pull ration not MTB).

I've just checked and Google is working now if you want to look for things yourself!

danlightbulb

Thanks. I have tried quickly searching google and ebay but its sometimes hard to know what is compatible and what isnt especially on drivetrain.

danlightbulb

Started my project today.



There is alot of dirt, grease etc all over everything so the first job is to thoroughly clean it all.

Can shifters (SRAM X7) be dismantled and refurbished?

What about derailleurs, can they be refurbed? On the rear mech I could replace the jockey wheels rather than the whole thing?

On the front crankset, the arms and spindle are fine so ideally if I could just replace the chainrings that would be a big saving.

Its amazing how light the frame is with nothing attached!

What Im planning on doing now is more of a touring bike for canals and some road. So any tips on what gearing ratios to go for and what fast rolling tyres but still good enough for a bit of muddy canals towpaths would be?

JBA

danlightbulb wrote:

There is alot of dirt, grease etc all over everything so the first job is to thoroughly clean it all

Laying it out on the lounge carpet is probably not a good idea then.

danlightbulb

JBA wrote:

Laying it out on the lounge carpet is probably not a good idea then.

No wife in my life so no one to moan at me.

Guys what gearing ratios should i go for? I could stick with what was on the original bike which was 11-32 rear and 44, 32, 22 chainrings. Or i could change to something more road/canal suited?

danlightbulb

Good news I think. Chainrings all removed just fine so I have a Shimano Diore crank in good condition to reuse. 104mm BCD so I think I now have a range of options for what do go for. So I now need to decide between fitting a new triple, a double or going single speed up front.



Im not sure what to do?

mark~p

If you turn it into a tourer with a rigid fork you have to get one that is specifically to replace a suspension fork. The crown height is less with a rigid and you will end up with a very low front. I looked at doing this on my commuter bike after the Suntour it was supplied with expired to the point it was not worth keeping on the bike.
I thought on of the Swing forks would be a good compromise, it wasn't and I sold it at a loss on eBay replacing with another suspension fork.
The crank looks fine and will be 104BCDD. If you run 1x at the front you will need shorter chainring fixings as they usually will not tighten up. If they are the original Shimano ones you cannot cut threaded bit down as they are titanium.
An XT shifter and derailleur will be pretty much bombproof but if you use a Sunrace cassesste you need a longer "B" screw. These are just 3mm bolts with a small head.

danlightbulb

Im not sure what gear ratios to go for. My full suss mountain bike which I use for trails is a 1x with a 32T front chainring and an 11 spd 10-42 rear cassette. The lowest ratio on this is 0.79 which I get on ok with at the trail centres I ride at. I do use the lowest gear alot on climbs.

If I was to fit a 38T front chainring and a 10 spd 11-36 cassette the lowest ratio would be 1.06. I don't know if this means I would struggle riding it on the road or not? I notice most road bikes are something like a 50/34 up front with a 11-28 rear. If I went for a 34T front single ring I wouldn't have much top end so is a double better?

It would be nice to do away with the front mech altogether really, but I don't know if I will lose too much flexibility?

bonzo_banana

danlightbulb wrote:

Im not sure what gear ratios to go for. My full suss mountain bike which I use for trails is a 1x with a 32T front chainring and an 11 spd 10-42 rear cassette. The lowest ratio on this is 0.79 which I get on ok with at the trail centres I ride at. I do use the lowest gear alot on climbs.

If I was to fit a 38T front chainring and a 10 spd 11-36 cassette the lowest ratio would be 1.06. I don't know if this means I would struggle riding it on the road or not? I notice most road bikes are something like a 50/34 up front with a 11-28 rear. If I went for a 34T front single ring I wouldn't have much top end so is a double better?

It would be nice to do away with the front mech altogether really, but I don't know if I will lose too much flexibility?

Is your full suspension mountain bike on larger wheels, 27.5" or 29" as that will higher the gearing so will be harder up hills. I'm totally biased and would always go 1x rather than have a front derailleur setup but 2x is a a possible solution if you want both easy gearing for hills and a high top speed on the road but personally I can find all I need in a 1x setup. 11-36T with a 34T single chainring should give a good spread of gears with 26" wheels I would of thought. Personally I probably would have gone for 42T with 26" wheels. I'm a masher/grinder though.

danlightbulb

From looking on chain reaction i dont think i can go to 42T front ring on a 4 bolt 104 Bcd crank.

Having never done much road or canal path riding im just not sure how low or high a gear i need. I assume having less knobbly tyres helps too? Im not too fussed about steps between gears just the most appropriate range. A 10 spd cassette is the most i can fit without changing the freehub which would probably mean new wheels.

I could pick up a new Shimano tiagra double crankset for £60 off chain reaction which is not quite double what id have to pay for just one single narrow wide ring and reuse my existing cranks.

danlightbulb

Been measuring up tonight and think the chainstays are going to restrict me a fair bit on what size rings I can fit. It seems borderline to be able to fit a 38T ring in the middle position so Id have to go for 36T. Is 36T front with 11-34 rear going to not give me enough top end speed? If i fit a single ring in the outer position is that going to give me a bad chainline?

The Rookie

To correct a few errors
You can most certainly get 42t 104BCD rings
You can most certainly use an 11 speed cassette as long as its MTB ratios, road type ratios need a wider freehub.

36T front would be marginal on road, I use a 46T front on my commuter. Fitting it on the outer will compromise your chainline.

danlightbulb

Ive not been able to find a narrow wide 42x104bcd chainring so far. I can get standard tooth ones.

Does a 11 speed cassette fit straight on or do i need to change the freehub body? My cassette was originaly a 9 speed sram. pg950 model.

I definitely wont fit a 42T on the middle position, it will hit the chainstay. I can go a bit bigger on the outer position but I dont think a road based 50T is going to fit either.

Not sure what to do now. Do i go back to the idea of a double with front mech or stick with 1x?

larkim

If it's a tourer, surely you don't need to restrict yourself to a NW 42T chainring as it won't be as susceptible to bouncing off as if it were being ridden as a MTB?

I suppose the frame is designed to be used with a double or triple, hence the possible compromise issues with chainline.

danlightbulb

Here is image of chain ring area. Chainstays flare out quite a lot.

billycool

danlightbulb wrote:

Ive not been able to find a narrow wide 42x104bcd chainring so far. I can get standard tooth ones.

Does a 11 speed cassette fit straight on or do i need to change the freehub body? My cassette was originaly a 9 speed sram. pg950 model.

I definitely wont fit a 42T on the middle position, it will hit the chainstay. I can go a bit bigger on the outer position but I dont think a road based 50T is going to fit either.

Not sure what to do now. Do i go back to the idea of a double with front mech or stick with 1x?

Can only offer an opinion on personal experience.

I have 3x9 on my HT and that is used for tracks/paths/tow paths etc. I don't use the granny ring so it's really 2x9. I do like being able to change up from middle (32) to big ring (44) on the road and faster sections. I have 11-34 on the back.

My FS is 11-42 with 34T NW up front. Great off road but spins out on the roads and fast tracks. It's not really meant for that so no issue.

Could go 1x and would suggest something around 40T+ up front (a potential issue if you try to put it on the middle ring position due to conflict with the frame - in the outer ring position the chainline would be off). 2x would give you the flexibility of 2 rings up front and potentially better gearing for what you want.

3x were good for changing to 1x as you just stuck a 34T NW in the middle ring position with shorter chainring bolts. The chainline was more or less sorted.

If it was me, I'd go 2x and get the gear flexibility that is suited to what you want and suits your current set-up.

The Rookie

https://www.ebay.co.uk/itm/DECKAS-MTB-B ... HcK09HCOHQ

danlightbulb

Yeah as much as id have liked to go for 1x on it for simplicity i think the range and chainstay issues are going to mean i have to go for a double. Damn thats really kinda dissapointing and going to add to the cost.

billycool

danlightbulb wrote:

Yeah as much as id have liked to go for 1x on it for simplicity i think the range and chainstay issues are going to mean i have to go for a double. Damn thats really kinda dissapointing and going to add to the cost.

Sooooo many people have changed 2x to 1x that you should be able to pick something up from the usual sites.

Get on Facebook and look up/join Coggers MTB Group. Loads of lads on there always selling/trading stuff.

2x is very appropriate in the right circumstances.

danlightbulb

The chain rings are cheap enough it just means new mech and shifter for the front. Not much point in buying used stuff that im unsure of the condition of, I may as well keep my existing mech and shifter in that case which still works but is worn and stiff.

bonzo_banana

Is changing the bottom bracket an option, maybe its a 72/73mm bottom bracket in a 68mm bottom bracket shell currently with a spacer and you could move the spacer to the other side or just replace the bottom bracket with the size you need. You may even be able to add a spacer if none currently exists and you have deep enough threads. Whatever works to move the chainring to where you want it.

Also while the chainline in theory should point/line up to the middle cog of the cassette you might find your favourite most commonly used gear is the next smallest cog so that could actually represent the most efficient chainline for you for power delivery and reduced chain wear. Personally on a 1x setup I wouldn't mind if the chainline ends up in either 1 or 2 cogs smaller on the cassette if it still works well but this depends on exact factors with your bike. The chainline can get a lot worse than that with a 3x derailleur setup. Even if you disagree about 2 cogs in surely no one is going to complain about 1 cog in on a 1x setup which might give you the clearance you need with your chainring.

danlightbulb

Ive just put my old 44T outer ring in the middle position with two spacers on drive side and it fits - barely. There is an A4 piece of paper's thickness between the chainring and the chainstay. The teeth are worn on that chainring too. But if that's a 44T, then a 40T would be around 8mm smaller radius than that and should go on?

So potentially a 40T chainring 1x up front and an 11-36 10 spd rear would give me ratios of 1.11 to 3.64. Is it low enough though?

If I was sticking with a double I could get away with something like a 48/36 which would give me ratios of 1 to 4.36.

Or if I wanted a bit more low end I could do 46/34 or stick with 44/32.

I just don't know which is best option.

bonzo_banana

Only you know your riding strengths and preferences. This is a good site for comparing different drivetrain setups.

http://www.bikecalc.com/speed_at_cadence

You could also use your existing bike as a comparison of how good it is going up hills or on the flats etc and try and match that if that is your preference. Mountain bikes tend to have lower gearing to enable you to go up steep inclines off-road so I would of thought you could move away from such low gearing a bit but again if its a full on touring bike that will get a ton of gear strapped to it you will want low gearing. Maybe look at commercial bikes that are configured as what you want and try to match that gearing. Even if you get it slightly wrong on first attempt you can change it down the line I wouldn't get too hung up on getting it perfect.

Personally I'm a right cheapskate if I'd worked out that a 42T chainring was perfect but there was a 36T chainring sitting on the shelf being unused you can guess which chainring the bike would ultimately be fitted with.

That's the reality of 1x drivetrains, they are more reliable, easier to maintain and you loose weight on the bike but they are a compromise with regard gear range unless you go for one of the extreme range cassettes. Personally I find 11-34T is all I need though.

billycool

If you have such limited clearance with 44T, does that include a chain being in place?

No idea if a 40 or 44T would give you what you want. If you go 2x then 32/44 is fairly standard with 11-36 at the back.

I'd still prefer 2x but that is only based on my preferences and experience. I'm not a big fan of a ghetto fix when there is an exisiting 2x set-up that would solve the issue.