'twinshock Shop' Top Yoke Ty175 ?

[alanp]

Just wondering if anyone has fitted a top yoke from the Twinshock shop to a TY175? Looks like it moves the bars to be more central to the steering line.

 

 Did it (or would it?) make much difference to the steering? Mine tends to 'flop' into turns, and it would be nice if I could slow this down a touch. (Have 360mm Betor shocks fitted, standard forks and yokes, forks flush with top yoke as per TY Trials recommendation. Steering head bearings are a bit worn and notchy though).

 

Edited September 5, 2016 by alanp

[feetupfun]

Before you spend $$$, try it with the tubes slid through a bit. Sliding the tubes up and down affects the trail and rake, as does changing the ride height at the rear. The way yours is set up, the standard rake is retained, but the trail is reduced compared with standard.

Standard bike steers very well (neutral) with tubes about 20mm through and 340mm shocks.

[alanp]

Thanks, I'll try the forks at 5mm intervals and see how it feels. Increasing the trial will slow the steering down a bit, yes?

 

I used to run in standard configuration - I was attracted to longer shocks for better ground clearance and have been fiddling about ever since!

 

Would rotating my bars back a bit have a similar effect? I've got 6in Renthals on the standard top yoke. Bar ends are currently about in line with the line of the fork legs, if that makes sense.

[goudrons]

Feetup describes what you need to try first, drop the yokes down the fork tubes until 20mm stick out the top.

 

You can mod the original top yoke to accept a decent set of bar clamps flush with the top.

http://www.trialscentral.com/forums/topic/40766-ty175-whitehawk/

 

I did a similar thing myself, just filled the hollows of the orginal risers from underneath with some Durafix alloy welding rods.

Cut the risers off on a bandsaw and drilled new holes for the clamps, single bolt ones work best.

Edited September 5, 2016 by goudrons

[johnmartin247]

 

My TY 250 Mono top yoke conversion by Cambs trials Centre.

[alanp]

Thanks for the yoke examples. I know Paul at Cambs Trials so will bear that in mind as well.

[feetupfun]

Thanks, I'll try the forks at 5mm intervals and see how it feels. Increasing the trial will slow the steering down a bit, yes?

 

I used to run in standard configuration - I was attracted to longer shocks for better ground clearance and have been fiddling about ever since!

 

Would rotating my bars back a bit have a similar effect? I've got 6in Renthals on the standard top yoke. Bar ends are currently about in line with the line of the fork legs, if that makes sense.

 

Increasing the TRAIL will reduce the tendency for the steering to be pulled towards the ends of the steering travel and reduce the steering effort when riding in rocks. I would not describe it as slowing the steering.

Rotating the bars forwards generally increases steering effort and rotating them rearwards generally reduces steering effort, however for many people riding a TY175 the bar ends get in the way of your legs unless they are rotated well forwards. Having the ends of the bars further forwards allows for better bike control because you can move around more. However there are limits for having the bar ends a long way forwards because you also need to be able to get your backside way back for big drop-offs and so arm length, body length and handlebar width are important factors.

 

[goudrons]

Rotate the bars too far forward and you end up riding with a twist in your wrists.

 

The bar ends where the grips fit are raked up and back slightly, so if you push them forward too much you tend to get your lower arms, wrists and hands all cocked up and out of line.

 

It can feel quite uncomfortable and after prolonged use like this, cause wrist and finger/grip problems.

 

Before you decide what needs doing, set the bars so they feel comfortable and you aren't twisting your wrists, it may take a while and a few adjustements needed, but keep trying the different angles on downhills when your weight transfers forward, if you are bracing yourself against the bars with too much bend in your wrists, try adjusting it out until you get near as you can to straight arm, wrist and hand.

 

Once set you'll probably find the what Feetup mentions, there's little room behind them to move the steering about without it digging in you.

 

As they were originally designed for youths and in a day where tillered yokes where common, most adults find the bar clamps (and bars) need moving forwards about an inch and lifting up around 1/2 an inch.

Edited September 7, 2016 by goudrons

[alanp]

Many thanks (and sorry for the trial / trail typo!). I have a trial coming up this weekend so I think I'll use it s a practice for some adjustments as suggested above. I'll let you know how I get on.

[tony27]

This is what my 250 top yoke looks like.

I cut the handlebar clamps off & machined the underside of them flat then machined the stumps on the yoke mainly flat before drilling tapping sized holes that lined the clamps up so that the stump & clamp were aligned. I tapped the holes in the clamp right through continuing into the yoke so I could screw both together, an old piece of handlebar was used to keep things in line during welding. The rear of the stump had a gap which was filled in quite early on & there was a substantial relief used to give good weld penetration. 

When the welding was finished the lower part of the original clamp stuck out behind the new top part & was filed down as part of the blending that I did. I still have the final sanding to tidy everything up & remove the casting marks before I get the yokes vapourblasted

You should be able to pick up another top yoke on ebay fairly cheaply & do this yourself without spending the kind of money that the billet ones cost

[alanp]

Thanks again - really useful.

I tried moving the forks up through the yokes (about 10mm) at a trial I did on Sunday. It was noticeably better and far less prone to the sudden 'tuck-in' feeling towards full lock. So heading in the right direction adjustment wise.

I'm not going to alter anything else until I've replaced the headrace bearings. They are much worse than I thought - clunking and notchy, basically totally past any useful adjustment. They can't be helping matters so I'll sort them out before any more changes.