UKC

What would really make my life better/easier as a mountain biker in terms of mtb design…

Well, the thing that comes to mind is a bike that needs less cleaning! Really, this is one of the biggest drags about mt.'s over road bikes.

And so, i got to thinking….
it must be possible to design a closed drive mechanism, where the gearing, chain, cranks and derailleurs are in a closed capsule that just needs a spray-down after a muddy ride and not this endless cleaning, degreasing and oiling palaver.

Im sure there are boffins working on it right now

In reply to Kimono:

I hired a mountain bike with hub gears a few years ago, which is quite close to what you want. You don't get such a big range of gears as with deraileurs but you get a closed gear system that doesn't need so much cleaning. Another downside is you have to stop pedalling to change gear....

In reply to bigbobbyking:

ok, thats along the right lines but I'm sure its not beyond the realms of impossibility to create an encapsulated normal system is it?
I

In reply to Kimono:

An easy way is to buy a cheaper groupset and not clean it! They last longer than the lightweight stuff too, the weight penalty can be solved by losing a bit yourself, or getting fitter!

Belt drive on a hub gear could work, I've also always wondered why more hasn't been done, though I can't imagine much investment as once it's fitted replacements parts would be rare...

In reply to bigbobbyking:

My commuter bike has a Shimano Alfine 11spd internal gear hub. It's got virtually the same range as a typical derailleur block, over 400% range or roughly 30inch to 127inch.

You don't have to stop pedalling to change gear, just ease up a bit more than with derailleurs.

I've seen mountain bikes with them but haven't ridden one myself - I suspect the hire bikes have the 8spd hub gear which has a smaller range.

Downsides: expensive, it's about £350 for the hub unit though there isn't much beyond that.
If you get a puncture then it's much more of a job to get the wheel off and back on.
Weight - the drive system is all centered around the rear axle rather than distributed between the rear axle and the bottom bracket.

You need to do a fairly regular oil change, roughly every 5000km, which is a bit of a faff but in practice it's about once a year.

In reply to Kimono:


There have been prototypes of such systems (along with belt drives with internal hub gears etc etc) at various bike trade shows for the last 20 years. They have never really taken off commercially, mostly because the price vs weight vs robustness of the chain-derailler system is difficult to beat (especially given that it has the benefit of 50+ years of R&D). There are handful of belt drive bikes on the market now, along with internal gear hubs, but they generally marketed at the urban/commuter sector.

So unless there is a dramatic change, I would resign yourself to old-fashioned cleaning for a while yet!

In reply to Alun:

One point to note about belt drives is that you can't split the belt in the same way that you can a chain so the drive side chainstay has to be splittable in some way. This adds complexity to the bike build.

I'm not totally convinced of the weight argument, a standard derailleur system has weight and it's not too dissimilar to that of the IGH. The big difference is in the weight distribution and bikes fitted with an IGH definitely feel "back heavy".

If you want to see what's inside then see the third post on this page http://forum.ctc.org.uk/viewtopic.php?f=5&t=64432&start=15

In reply to Kimono:

here you go: http://www.pinkbike.com/news/Pinion-Gearbox-First-Ride.html

In reply to Bob:

I agree that the weight issue is not a real problem for IGHs - although for full-suspension mountain bikes you still have to factor in the weight of a chain tensioner to soak up the differences caused by suspension movement.

I think the bigger issues are related to price, durability and ease-of-maintenance. FWIW if somebody showed me a durable IGH for 200 bucks which I know wouldn't split apart the next time I fall down an Alp, then I'd buy one!

In reply to Kimono:
Sounds like you want a shaft drive.

http://www.dynamicbicycles.com/chainless/

Personally I think there ugly and unnecessary, it's not that hard to hose it down (if you have to clean the bike in the first place) and apply your lube of choice.
I leave it dirty and give the chain a quick coat of lube before a ride, this takes about 30 seconds.

In reply to Alun:

I think the price of the Alfine is around £350 which compares to about £220 for Shimano SLX which is probably a reasonable equivalent. Obviously XT & XTR are going to be much more expensive.

Maintenance: It's comparing a lot of little regular fiddling jobs (traditional mech) with one big maintenance job (IGH). The tools for traditional mech are readily available whereas those for the IGH aren't.

I don't know how durable the IGH would be with regular MTB style usage as it's not something I do with my commuter (!). The only IGH equipped MTB's I've seen out on the trail have been rental bikes at Rothiemurchus so aimed at the family style rider rather than the more sporting rider.

In reply to Bob:

Several years ago I met a guide in Morzine who had a Shimano IGH (I forget the range name) on his bike, which was thrashed day-in-day-out down big mountains, and he was full of praises for it. He did, however, take it apart once a week or so, I think.

Rohloff have made an mtb IGH for years, and it is very well reviewed for its performance and durability.....but it costs the best part of a grand!!

In reply to Kimono:

Its all about mechanical loss. The chain drive is very efficient compared to gear on gear contact. I had been pondering a mix of belt to enclosed cog but it all adds up to more weight. Also the derailleur needs a bit of chain length to work.

I think a lightweight plastic housing is the only way.

I run 7 speed with a spacer ring so it fits on the modern freehub for 8/9/10. £5 each plus P&P... I think the spacing might be different between the cogs making cleaning a bit easier (but that's not why I stick with 7 speeds).

In reply to Kimono:

I run an 8 speed alfine on my inbred 29er. I use it to commute with cyclocross tyres and also mountain biking with Hans dampf on. I have more than one bike but this is always my first choice, the hub gear is great, not really run out of gears only on road sections, pretty maintenance free, instant response when changing, can chage gear in any situation..including stopped!
I cant say as the weight being focused where it is has ever made any difference at all. For me i cant understand why it has not caught on enormously.. have seen a few mtbers out (not many) with alfines off road, when we have chatted we have all said the same thing...why does anyone bother with derailleurs!!!

In reply to quirky:

What gearing do you use for MTB riding? I know Shimano recommend a minimum 1.9 to 1 ratio but quite a few run lower than this.

In reply to Bob:

Its stock 8 speed alfine on the back i think its 26 and 32 on front... will have to check

In reply to dapoy:




well, each to his own, but my cleaning schedule is a little more rigorous than this!
Thus my point

In reply to Kimono:

I had a motorbike (a Honda CBX 550 - remember them?) with encased disc brakes that supposedly needed less maintenance. The opposite was true because they got mucked up and seized whenever the weather was wet.
This could still be the problem for mtb design?