Topic: Clearance Consensus

[Matty-Wan]

Hello all,

I am trying to gather consensus among the community on the safety risks and handling sacrifice proportional to the clearance reduction on a CB750.  I have read many of the threads in this forum and I still do not feel as though I have enough insight into the matter to commit to a drop size. 

So you understand where I am coming from my interest in the lowering my 1976 CB750K is NOT for style.  It comes from me being a fairly short rider coming in at 5’7.  I would very much like to have my boots planted firmly on the ground when not at speed.  I am mostly a daily rider, I rarely get too aggressive except on those occasions when my bloods up.

After reviewing many of the different strategies I am currently leaning towards installing shorty rear shocks (11.4”, a 2” drop from stock) and bringing the forks up through the tree to level the bike.  Combined with a seat with a low profile I imagine that should do the trick.  That said, I am open to suggestions as to why I should consider some of the other methods I have read about.

I think what I need most clarification on is what an inch reduction actually represents.  While 2” doesn’t seem very much the spec sheet for the 76 says the clearance is 5.5” so a 2” drop is a reduction of close to 40% which does seem like a lot.  I also would be open to any additional thoughts on the potential obstacles one may encounter when modifying the original geometry.  Immediately I think of a fender or at some point a rear hoop rubbing.  Maybe there are exhaust options that lend themselves to a lowered bike?

Essentially what I am looking for is a sweet spot; that optimal height reduction that improves my stability when not moving and sacrifices the least amount of safety.  I accept that any modification to the height will invite some risk, some of which I am willing to assume in a tradeoff but obviously there is a cost-benefit threshold I am not willing to cross.  I also understand the handling will change so I would like to incorporate that into the calculation as well.

Thank you in advance to everyone who takes the time to offer any insight into this matter.

Best,
Matt

Oh btw, at some point in its nearly 40 years, the stock 18” rear wheel was swapped out with a 17”.  So, I guess I am already going in the right direction.

[kingrabbit]

Out of curiosity what are you wearing on your feet when riding? I am 5'7" also and have a '75 CB750 Supersport. I always wear harness boots - the heels are over an inch tall. Sturdy and safe footwear. Plus it helps with the vertical challenge.
Admittedly I rarely put both feet down.
My left foot stays on the peg at stops.
Respectfully,
Donny

[Nic]

I'm 6'1" and I rarely put both feet down either. One is enough IMO.

[Stev-o]

A couple questions.....are you a fairly new rider?  Why do you think it is necessary to have both "boots planted firmly on the ground"?

What year is your 750?  The '77-78's came stock with a 17" rear wheel.

[Matty-Wan]

Nope not a new rider, had my rf600 for years but my CB is new.  I know its not necessary, its current height doesn't prevent me from riding it.  It is just a preference I think I would enjoy.

[calj737]

It's always been my experience that any bike I've ridden where I can firmly plant both feet on the ground tends to be too short to be comfortable riding. Makes my legs cramped up when on the pegs.

Ideally, balls of your feet should touch comfortably, but the entire sole of your foot is not really requires. But you know your comfort best, and if that's your preference, then let's get some ideas flowing to hep you achieve it.

From your post, the only thing I'd investigate carefully is the clearance of the lower tree and the fender if you pull the forks through the top. Compress them fully and insure you can't bottom out.

[bjbuchanan]

Wait on a lower seat, the stock seat may actually be better. The foam is better shaped for the inside shape of your legs. The bottom of the seat won't be any narrower so you don't gain any height from it, it is just for uncomfortable feeling.

[BobbyR]

I am slightly taller but have the same feeling you do. I find backing the bike up into parking space is not easy with only one leg touching the ground sucks.

I have done no lowering yet but I do not see a big deal with it. 

[Don R]

My Brother has lowered his 750's for decades. He uses lowering blocks on the rear and slips the forks an inch up into the trees. I'm not a fan of lowering blocks the shock idea is better. Check the fender to header clearance, he swapped out pipes and promptly dented his fender when he hit a bump in a turn.
 Lowered stock seat foam is pretty common in Japan, Yamiya sells seats with lower foam.

[MiGhost]

For the front you can get shorter springs for the forks, or reduce the length of the spacer if one is installed.
Remove the fork boots if installed, and place a zip tie on the tube. Do a hard stop to determine how much travel you have to figure out how much can lower the forks.

[Mr Freeze]

I'm 5' 9" and I felt the same way you do about lowering the bike when I first got my 750. I ran 11.5" short shocks in the rear and slipped the tubes in the front to level it out. I ran it this way for a while until I made a new seat. By 1976 the seats were starting to get pretty thick (mine was a 1978) You'd be suprised how much having your seat redone with modern foam can make a difference. You can take out 1.5" and kind of sculpt the rider position and it'll still be comfortable. Sort of like this one.



Not that lowering the bike isn't an option too, but I found that after running with shorter shocks and slipped forks for about a year, then going back to 13" shocks and bringing the forks back up that I liked the way the bike handled a lot more afterwards. I never had any problems with clearance when the bike was lowered though and was able to ride aggressively on windy roads without any problems.

[goldarrow]

Whatever you decide, I have a pair of 11.5" shorty shocks if you're interested.  But like everybody else said, you don't need whole feel flat on the ground. MSF course mentioned this: at a stop light, clutch in, first gear, right foot on brake, right hand on throttle, left foot on ground, ready to go!

[Retro Rocket]

Not that lowering the bike isn't an option too, but I found that after running with shorter shocks and slipped forks for about a year, then going back to 13" shocks and bringing the forks back up that I liked the way the bike handled a lot more afterwards. I never had any problems with clearance when the bike was lowered though and was able to ride aggressively on windy roads without any problems.

You couldn't have been riding too aggressively if you weren't scraping the pegs mate, they are pretty easy to scrape on the Honda 750's, I used to scrape the mount under the peg after having the pegs completely folded up and i wouldn't call my riding style that aggressive, I can scrape the pegs just doing a U turn, I have friends that ride a lot harder than me, i've even seen the stator covers scraped {thats aggressive  }.. The OP still hasn't told us which model he has, if he has a 17 inch wheel on an early K model and uses 2 inch lowered shocks, he's effectively lowered the bike 3 inches at the rear, personally i would find that dangerous for spirited riding through the mountains or twisties, no to mention the amount of front suspension lost trying to match the height of the rear. The seat mod is what i would try first..

[lrutt]

A couple questions.....are you a fairly new rider?  Why do you think it is necessary to have both "boots planted firmly on the ground"?

What year is your 750?  The '77-78's came stock with a 17" rear wheel.

SOHC or not, both feet are good and were a necessity yesterday the way the wind was blowing. Hell of a cross wind at a stop light had me swaying back and forth pretty good. I think if it makes the person confortable and gives them confidence with both feet on the ground then that's the way it should be. The only time I really use just one foot on the ground is when riding the old 34 Harley with a foot clutch.

[Mr Freeze]

Not that lowering the bike isn't an option too, but I found that after running with shorter shocks and slipped forks for about a year, then going back to 13" shocks and bringing the forks back up that I liked the way the bike handled a lot more afterwards. I never had any problems with clearance when the bike was lowered though and was able to ride aggressively on windy roads without any problems.

You couldn't have been riding too aggressively if you weren't scraping the pegs mate, they are pretty easy to scrape on the Honda 750's.

Oh I used to scrape the pegs, but that's the fun part! I do like my bike more at stock height though. I think maybe for someone new to having a 500 lb. bike between their legs that makes them stand on their tiptoes can be intimidating. Don't be afraid to cut the seat down.

[Retro Rocket]

Not that lowering the bike isn't an option too, but I found that after running with shorter shocks and slipped forks for about a year, then going back to 13" shocks and bringing the forks back up that I liked the way the bike handled a lot more afterwards. I never had any problems with clearance when the bike was lowered though and was able to ride aggressively on windy roads without any problems.

You couldn't have been riding too aggressively if you weren't scraping the pegs mate, they are pretty easy to scrape on the Honda 750's.

Oh I used to scrape the pegs, but that's the fun part!

I remember the very first time i scraped the pegs, i sh1t myself... , I wasn't ready for it and it freaked me out...

[Mr Freeze]

Imagine doing it on a bike without sprung pegs, then you'd really paint your trousers brown.

[evanphi]

When I got my bike it had lowering blocks and the forks raised about an inch in the tree. I put it back to stock height this season and I like it better.

32" inseam, doc martens for boots, and I can get the balls of my feet on the road no problem.

Lessons learned:
- Lowering the front one inch isn't an issue
- Lowering blocks in the rear SERIOUSLY stiffen the rear end. Buy shorter shocks, if anything.
- Clearance was no problem, except my 4-1 collector didn't like ramps onto trailers.

[lucky]

Hello all,.......(Shortened to save space).
Thank you in advance to everyone who takes the time to offer any insight into this matter.

Best,
Matt

Oh btw, at some point in its nearly 40 years, the stock 18” rear wheel was swapped out with a 17”.  So, I guess I am already going in the right direction.

You are over thinking this a little too much.

The 11.4 inch shorty shocks with lower seat will work just fine. Very common set up.
Do not forget to add in the rider weight.

The handling will not be any different.
Nothing you will notice .
The 17 inch and 18 inch wheels with tires ON will be very close to the same height.
But you would have to tell us WHICH tires were used with each wheel.

[MCRider]

If this hasn't been touched on...

Remember the 11.5 v stock (13? for discussion) is not a drop of 1.5", since the shock is not mounted vertically. At its angle, my guess is the shorty buys you a vertical inch. +

[Don R]

If my pegs get scraped it's because I fell off!

[Matty-Wan]

Thanks for all the input everyone.  I do admit it is entirely likely I am over thinking this.  But, I suppose I go with the axiom it is better to over think something than not think about it enough.  I am feeling a lot more comfortable with my original plan now.  As for the model of the bike, I stated in my OP it is a 1976 CB750K.  The front and rear wheels (The rear I suspect is off a 77 CB750 but I need to look for some kind of ID number) are on Bridgestone S11 Spitfire tires.

@MCRider, of course!  I can’t believe I didn’t think of that, the drop will not be the full 2” because of the angle.  Thank you for that observation.

Speaking of exhaust, I planned to install a 4 into 1 at some point but I am wondering if there is another system available that rides a little higher.  The CL350 scrambler comes to mind.  Maybe there is a similar exhaust out there for a 750?  Or something in between?

I have a plan for the seat.  There is a community craft guild in my area that offers upholstery lessons.  I am pretty sure it is for retired folks but I plan to insert myself in it anyway.  I am currently looking for a 76 or any hinge CB seat on ebay now.  I am going to slice it along the tank weld and reupholster it.  I think that will work nicely.

@Goldarrow Ty for the shock offer, when I am ready to get to work maybe we can work out an arrangement.

Thanks again!
Matt
 

[goldarrow]

Be sure to replace fork seals when you remove the front forks off the bike.