Let's offroad / mountain bike / mtb / ride dirt

according to sheldon browns gear calculator i run a 67.5 gi on my all rounder ( 26" 1.5 tyres 38-14)
spinning before a hill is the way to go, the momentum will usually take you up the majority of hills, long climbs are a bitch and very steep long climbs are sometimes impossible (when i have traction i cant turn the crank with all 14 st of me behind it and when i don't i just wheel spin) which usually results in hand on saddle and jogging

its possible if your willing to compromise a tad

ATB

Ahh, realised my mistake there. Twas a simple math error on my behalf. Coming out at 64.2 now for the 2.35 tyres and 66 for the 2.55s. Though they're probably not that accurate either as tyre manufacturers have a tendancy to be a pretty inaccurate with their measurements at times.

I think it's probably going to be a little below those numbers, as you're going to be running slightly lower pressures which will mean less tyre height at the ground and therefore lower GIs. Might be wrong though.

have been on 55 on the 26 in SS for ages now, its obviously spinny on fire/ roads-
but when on trails keeps most climbs that arent real 10 min grinders manageable.
glad this has been raised actually, because when I finally get the wheels I bought off Tilover, going to go fixed 29ering, and figured on something like 67/ 68 whatever I can get to work best mechanically. Really looking forward to trying it now too, although sitting here cogitating, why shouldnt I get a 55 again? will the bigger wheels on the 29er mean I need to gear up?

I've been using my road ratio (68GI) off-road (I forgot to bring my other sprockets with me) and have been finding it pretty good. When it comes to technical ascents it's pretty difficult at times but bombing along fireroads I definitely wouldn't want anything much smaller.

Ouch! I'm running (I think) 56GI and I would say that is about right to verging on a bit high for flat stuff, irrelevant for downhill stuff and far too high for climbs. Unless you are racing then there is no need to blast the fireroads. Especially if you are in a group, the fireroads are where people take it easy and chat. For flat single track then (hopefully!) the trail is too twisty, rocky, rooty, etc to blast at speed anyway. Yes, there are trails where I could go faster with a higher GI but there are a lot more where I am pushing hard to go the speed I'm going.

For downwards pointing trails, it's rare that you need to pedal your way to something faster than gravity will get you too. Again, this is especially true if it is a particularly technical (a.k.a. fun) trail. The only time you really do need to pedal into stuff is if you are into huge jumpy things and genuine downhill tracks that warrant body armour and full sus bikes.

For climbs, I can just about manage a steep fire road. Even then, there were a few yesterday that had me stumped. However, that was the major reason for going SS in the first place - to get fitter and better at climbing. The major problem is loose or muddy ground where you can't grip because you have to put so much power into the pedals. With lower gears you can spin and roll over stuff, with a fixed and high GI then you just wheel spin or stall. And that's only on fire roads. Any kind of long technical climb is another matter entirely - if it is also steep you have no hope at all.

I was up in the Peak District the first weekend when we had snow (end of November?) and it was almost impossible to climb anything. Admittedly, even those with gears still had trouble in a few places but I was just buggered!

If you can manage off-road XC on 68GI, I would be very impressed indeed. Even 63GI still sounds high. You should definitely come along on the next Swinley Sunday and show us how it's done :).

PS: I'm running 26/12 with 26x2.0 (50-559).

pretty on the button that post ^^ yep yep hear ya.
sitting right back, getting your whole leg into the climbs can get you up stuff, along with plenty use of the upper body. this is where mtb training is way better than road- couple of hours of full body work out equals a 6o miler easy.
the other thing I do to clean grunty climbs is to just before it, suck in about three massive breaths, satuarating the lungs with oxygen, seems to work for me.
yeah Im gonna get a lower gear sorted for new build, makes sense.

"The major problem is loose or muddy ground where you can't grip because you have to put so much power into the pedals. With lower gears you can spin and roll over stuff, with a fixed and high GI then you just wheel spin or stall. And that's only on fire roads. Any kind of long technical climb is another matter entirely - if it is also steep you have no hope at all."

this is the point baby ^^ the buzz, the zone, to clean that shit up and rinse it out.

off road is ratios 1.8:1, 2:1 etc road and track is gear inches.

1:9 or 50in for me. spinny but i never get off and walk up any climbs and learn to carry speed by working the bike. i have no problems keeping up with geared riders. it's tedious riding on the road though but only have the short trip to the train station on tarmac

that's for proper mtb'ing if it's just towpaths and doubletrack then you need a nodder gear.

sitting right back, getting your whole leg into the climbs can get you up stuff, along with plenty use of the upper body.
I find that sitting back just leads to wheelies on steep climbs! I have to keep my weight center to forwards depending on just how steep. Certainly plenty of pulling up on the bars while pushing down on the legs though. With loose stuff, I also find it helps to shift your weight forwards and backwards with each pedal stroke. Using your own body momentum to keep the bike rolling fowards kind of idea. Either way, there is definitely a lot going on above the saddle as well as below it.

yeah I was talking shit there, I havent been online for a few days got a bit of burbling going on ;-)
of course you have to get a balance between maintaining equal weight distribution over the wheels to keep traction, sometimes sitting right on the nose works,
was trying to express this to someone actually, sometimes the motion is like rowing in a funny way,
like, pulling one bar then the other towards you whilst the opposite leg goes forward.

off road is ratios 1.8:1, 2:1 etc road and track is gear inches.
I suspect that's largely down to not caring about the accuracy so much. 55GI vs 55.5GI vs 56GI makes no odds and ratios are a lot easier to a) understand and b) calculate. [Whether that is implying MTBers are thick or roadies are number geeks I couldn't possibly comment] I'd never even heard of GI until I found this site. However, with 29" wheels there is quite a difference. My 2.2:1 ratio is 56GI on my 26" wheels, switch to 29" and you get 64GI. You would need 1.9:1 to keep the same GI.

that's for proper mtb'ing if it's just towpaths and doubletrack then you need a nodder gear.
That's my big problem. I use the SS for general day to day stuff as well as having fun in the hills. Dropping to a more MTB friendly ratio would make for much slower pootling about on tarmac. And I can't be arsed to switch cogs all the time.

now my head is spinning not my legs with these ratios...

now my head is spinning not my legs with these ratios...
Are you sure that's not just from over doing the partying the last few days?

yep, dont drink, smoke or do drugs, like adrenalin though.

Ouch! I'm running (I think) 56GI and I would say that is about right to verging on a bit high for flat stuff, irrelevant for downhill stuff and far too high for climbs. Unless you are racing then there is no need to blast the fireroads. Especially if you are in a group, the fireroads are where people take it easy and chat. For flat single track then (hopefully!) the trail is too twisty, rocky, rooty, etc to blast at speed anyway. Yes, there are trails where I could go faster with a higher GI but there are a lot more where I am pushing hard to go the speed I'm going.

That may be part of the reason why I use such high gearing, fireroads are probably my favourite part of off-roading, hence choosing a high enough gear to pedal fast enough for them.

And i'll definitely be going to Swinley on Sunday, first time i've had a Sunday off in ages and i'm not going to waste it!

I'm running 32/18 which makes about 1.8:1 and 51-ish GI I think. I found this about right for Swinley. There were a few climbs I couldn't make but these were primarily due to my abysmal strength and fitness.

That's my big problem. I use the SS for general day to day stuff as well as having fun in the hills. Dropping to a more MTB friendly ratio would make for much slower pootling about on tarmac. And I can't be arsed to switch cogs all the time.

i used to run a dingle speed with an off-road and road gear. if the cogs and chainrings add up to the same number there is enough chain tension for each. mine was one tooth out but the extra distance the chain needed to get to the top and bottom of the bigger chainring took up the slack.

think it was 34/17 and 42/12 took seconds to change the ratio over. i would fit slicks for the commuting though.

i used to run a dingle speed with an off-road and road gear.

Meaning a flip over wheel with a cog on both sides? Haven't got the right kind of hub for that. I've also only got a granny ring with middle bash guard up front so no room for an alternative ring. That was mostly done because I kept catching my rings trying to hop up or over stuff. Not too bad when it's just a log but a big boulder can do nasty things to your teeth :(.

i would fit slicks for the commuting though.
That's my other problem, I've got almost slick tyres on which doesn't help off-road. Again, I can't really be arsed to switch tyres every weekend.

I wonder if the 3 speeds disc hubs might be any good for off roading.

doubt it Ed, range is bit off wack, shifting not fast, better on road,
Hendrik-
simple solution, get more bikes.

And i'll definitely be going to Swinley on Sunday, first time i've had a Sunday off in ages and i'm not going to waste it!
Well, there will probably be the usual posse heading out there again. Although, you might have to wait for us if you do like to blast off into the distance on the fire roads.

PS: What happened to mdizzle? I thought you were planning to come out yesterday too?

Hoping my shoulder will be up to it by next weekend.

Meaning a flip over wheel with a cog on both sides?

no. i used a profile 6-speed disk hub (made for 4-x racing) as it had a wide enough freewheel body for 2 wide based cogs. the hope SS hub works as will any 9 speed hub.

i don't do freewheels or v-brakes

I wonder if the 3 speeds disc hubs might be any good for off roading.
I've never really looked into them but I don't think they give you much range. The ideal for me would be a full set of chain rings at the front and a single rear cog but without all the problems of derailluers. That would give you a climbing gear, a general purpose gear and a speed gear. All you ever need.

The one I'm waiting for is the ridiculously expensive Hammerschmidt cranks to become more sanely priced. You only get two gears not three but even that would make life a lot easier.

Re: multiple bikes. Well I do have a full-sus that is meant to be used for off-roading. It's just that the SS hard tail is too much fun :). Plus the full-sus is currently in pieces and needs putting back together.

Ed, I was looking into using a geared hub for mine but the main problem is that it screws up the balance of the bike, sticking an extra kilo and a half right at the back of a 12 kilo bike is gonna be bad news.

Hendrick, maybe using the fire road for sprints is a good way to up your fitness!

Hendrik.....went out with Hounslow Wheelers instead.....couldn't be bothered to change tyres on the cross bike.....

I know this is a bit OT but how do you go about finding a rear wheel to run both fixed and disc brakes at the same time?

If anyone could point me in the right direction that would be awesome,

Cheers