Technical > General Technical

Sherpa 'Trail' and tyres; feeling unstable downhill

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pondweed:
Thanks all

yes, I was going to get out my child's protractor! I notice Dan has worked out his from his other post but wrong frame for me  :)

Sounds like I should get some new tyres first.

Be interested in widths of peoples' bars on the Sherpa. Don't think I have much option on these ones as the curve means I can't shunt things along.

StuntPilot:
My Thorn Raven Tour also feels a bit twitchy downhill on rough terrain, but only when unloaded. Fully loaded with front and rear panniers its a whole new world of stability.

Might be worth experimenting with racks and bags on the bike to see the difference if indeed fully loaded touring is the aim. If for use without panniers, I agree that wider tyres are a good place to start.

The stem seems quite long as has been mentioned. A shorter stem may impart less leverage on the fork and its steering and greater stability. However you say that the 'straights seem short in body'. A short frame with straight or comfort bars took a little getting used to after drop (road) bike handlebars.

After a couple of long tours though and a lot of fiddling with seat position and Ergon grip position I have ended up with a pretty comfortable position. I aimed for equal weight on saddle, handlebars and pedals.

What about shoulder width in relation to your handlebar width? Perhaps swapping out to wider straight bars if you have wide shoulders?

I would leave the protractor with the dividers in their box for the moment and ride on for a while  ;)!

pondweed:
Thanks. Ok, so yes, I'll get panniers sorted and put my front bag on.. with some 'stuff' in..

I was surprised how well 1.25 Marathons did on the tow path out from Bristol to Portishead, so was wondering whether a larger size of those, or to go for the lighter Marathon Supreme. Dureme seem too heavy if I want to use it for everything?

Tyres... shall I go for 1.6 (not big enough rise?) or 2.0? Inevitably I'm going to be on road a lot but want to be able to do firetrail and mtb-lite stuff.

mickeg:
Tires on my Sherpa for touring with camping gear, if mostly on gravel I use Dureme on front in 2.0 width (50mm).  But if mostly on pavement (tarmac) I use Marathon (with Greenguard) in 1.5 (40mm) width. 

But if riding unladen on gravel trails comparable to tow paths, the 40mm wide Marathons are adequate, I do not bother to switch to the wider Duremes.

The Duremes I use are the old discontinued ones for solo bike use.  The Duremes that are sold for tandem use are a much stiffer tire. 

I accidentally bought a tandem Dureme, I bought it mail order and I thought I was buying a solo bike tires.  I occasionally put it on my Nomad, but it is stiffer than I like.

martinf:
Marathon Supreme are quite light, even in the fat 50 x 559 size. I have these on my two Raven Tour bikes. In my experience they cope OK with moderate off-road use on paths and tracks, and are very good on tarmac roads.

Marathon Supreme also last a reasonably long time, not yet worn out any, and still plenty of tread on the longest-serving pair with more than 9,000 kms on the front and 5,200 kms on the rear.

Downsides are the high price, and I reckon the light sidewalls will be more likely to suffer damage if you hit broken glass or sharp rocks.

Duremes (which I also have, now on a visitor bike) are slightly heavier, slightly slower, and seem sturdier, so maybe a better choice for expedition touring.

I recently changed the tyres on my old 650B utility bike, so have been able to do a direct comparison. I had been using 44 x 584 Marathon Standard for several years, these are a good sturdy tire but a bit on the heavy side. First of all I used 42 x 584 Marathon Supremes, these were significantly quicker, then I fitted 50 x 584 Marathon Supremes, not quite as quick as the 42 x 584 bit still quicker  than the 44 x 584 Marathon Standard. When riding off-road, the 50 x 584 Marathon Supremes are much better than either 42 x 584 Marathon Supremes or 44 x 584 Marathon Standard, and are also more comfortable.

The 42 x 584 Marathon Supremes went to my wife's bike, where she found them a significant improvement over the 44 x 584 Marathon Standard she had before. Clearances on her bike are insufficient for the 50 x 584 tyres.

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